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listxattr EFAULT #503
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OK, I've got another one...
But interestingly:
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It's not immediately clear how this can happen, if you can come up with a consistent reproducer that would help a lot. Alternately, if you install systemtap on your system you can get a detailed kernel stack the next time it occurs by running the following. That will show exactly how the EFAULT is occurring. # stap /usr/share/doc/systemtap-1.4/examples/general/para-callgraph.stp \ 'module("zfs").function("*@module/zfs/*.c")' \ 'module("zfs").function("zpl_xattr_list")' -c "getfattr -d aaaa" |
Of course, in the grand tradition of heisenbugs, once I booted the box into a systemtap-enabled kernel, I'm no longer seeing the problem. I imagine that's due to the reboot rather than deliberate mischievousness from the FSM. I'll let you know if it pops up again. (I hadn't looked at systemtap previously - WOW!) |
OK, I have another xattr "Bad address" case. Interestingly, this one survived a reboot. Stap output:
In contrast with one that works:
Hmmm, am I reading that right? The one that works is a directory-base xattr, whereas the one that doesn't work is an sa-based xatter? Interestingly, 'getfattr -Rd .' tells me that of the 1107 files in that directory, which would all have been created in the same rsync run, 4 come back with the 'Bad address' problem. If I create a new file and set the xattr:
Stap on that file shows a similar output to the older file that worked, i.e. starting with zpl_xattr_filldir rather than zfs_sa_get_xattr. The file system was created with, and is now definately set for xattr=sa:
...so, aside from the "bad address" issue with the sa xattrs, why is it using directory xattrs (if that is indeed what it's doing)? |
Looking at one of the files with the xattr problem, and with "getfattr -d" vs "getfattr -n":
I'm confident the 'user.rsync.%stat' xattr would have been set on the file as it's a part of the rsync transfer. Then, explicitly setting that xattr:
The stap output for the '-d' case:
The stap output for the '-v' case:
Huh? No zfs usage at all? ...or, more likely, stap simply isn't being told to trace the relevant path. At this point my knowledge of what the relevant path might be, how to point stap towards it, and whether it's even relevant, all fail me! |
The stap output is very helpful. The problem appears to be that nvlist_unpack() in zfs_sa_get_xattr() is returning EFAULT. Now my understanding is that indicates an encode/decoding error although why that's the case isn't clear. If you add the As for whether sa or dir based xattrs are used depends exactly on the situation. Even when you have xattr=sa set individual xattrs which exceed 32k will be created as dir xattrs instead. Additionally, if your xattrs on a single file total more than 64k new xattrs with be created at dir xattrs. Both cases should be really unlikely on a Linux box since for example ext4 has a hard xattr limit of about 4k. This spill functionality is just provided for additional compatibility. Also because directory xattrs once created never get automatically migrated to sa xattrs we always check the dir and sa xattr namespaces when listing them. |
Below is the stap incorporating module("znvpair").function("@module/nvpair/.c") for a failing listxattr. I'm confident the filesystem in question was originally created with xattr=sa, and the only xattr set on a file is like user.rsync.%stat="100700 0,0 123:123", i.e. significantly smaller than 32k. So I'm surprised that where I've looked at a few files where the listxattr works, they all appear to have dir xattrs. Is there any way of telling, other than the stap fingerprint, whether a file has sa or dir xattrs? As an aside, are there any suggestions as to what to do to enable the stap module to unload? I'm using systemtap 1.6 and per previous dumps, every stap run ends like:
...leaving the module installed. Doing an "rmmod -f" on that module causes a kernel NULL pointer dereference. Google is suprisingly unforthcoming (or perhaps it's my google-fu). As I'm unsure of the consequences of having multiple stap modules loaded, I'm forced to reboot between every stap run - a tad annoying! The stap output:
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Make sure your stap kernel has CONFIG_MODULE_UNLOAD=y. This script might help identify the peculiarity of your setup: http://sourceware.org/git/?p=systemtap.git;a=blob_plain;f=stap-report |
Yes, I definitely have CONFIG_MODULE_UNLOAD=y. Thanks for the info on removing the @filename part. I haven't tried that yet as the problem seems to be fundamental in system tap as even a simple script like:
...fails the same way (can't unload the module) and the people over at the systemtap mailing list are helping me with this issue: http://thread.gmane.org/gmane.linux.systemtap/18785 |
Note: my stap problem has been resolved (was due to incompatible gcc versions for kernel compile vs stap module compile) so it's now easier for me to stap as much as might be useful. |
From the stap output above, the first sign of failure comes from nvs_xdr_nvpair:
...so I put some printk statements in there to see which part was returning EFAULT:
Then I used stap to trace all spl/zfs calls (script below) whilst running the failing getfattr. The kernel spat out:
The stap output was:
Stap script:
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chrisrd, for what it's worth, the equivalent of inserting printk's and recompiling could be using statement probes: probe module("zwhatever").statement("*@dir/file.c:2322") { println(pp()," ",$$vars) } |
@chrisrd Thanks for doing the leg work on this. Your debugging suggests there may be some flaw in the xdr decoding implementation. This error case in particular indicates that we ran out of bytes in the stream before decoding the excepted length. Could you try commenting out this specific error case and running to test again to see if your able to access the full xattr. |
On Wed, Jan 25, 2012 at 07:11:21AM -0800, Frank Ch. Eigler wrote:
Gob. Smack. Just amazing! ...now to start reading the systemtap manual to see how to dig into the XDR structure. |
No, with the "*size > NVS_XDR_MAX_LEN(bytesrec.xc_num_avail)" error return patched out it's getting a little further but still failing:
Note 1: added to previous stap script:
Note 2: the above stap output was for the second run. The first run produced a 53k line output (with all spl/zfs functions monitored) - I imagine the difference between accessing uncached vs cached. If interested the output for the uncached case is available here: http://www.onthe.net.au/private/stap.out.bz2 |
A private SA handle must be used to ensure we can drop the dbuf hold on the spill block prior to calling dmu_tx_commit(). If we call dmu_tx_commit() before sa_handle_destroy(), then our hold will trigger a copy of the dbuf to be made. This is done to prevent data from leaking in to the syncing txg. As a result the original dirty spill block will remain cached. Additionally, relying on the shared zp->z_sa_hdl is unsafe in the xattr context because the znode may be asynchronously dropped from the cache. It's far safer and simpler just to use a private handle for xattrs. Plus any additional overhead is offset by the avoidance of the previously mentioned memory copy. These forever dirty buffers can be noticed in the arcstats under the anon_size. On a quiescent system the value should be zero. Without this fix and a SA xattr write workload you will see anon_size increase. Eventually, if enough dirty data builds up your system it will appear to hang. This occurs because the dmu won't allow new txs to be assigned until that dirty data is flushed, and it won't be because it's not part of an assigned tx. As an aside, I typically see anon_size lurk around 16k so I think there is another place in the code which needs a similar fix. However, this value doesn't grow over time so it isn't critical. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue openzfs#503 Issue openzfs#513
Apologies for the delay in responding, I've just had a chance to look at this again... Is it expected that the xattrs added to files whilst running with I've just tried openzfs/spl@a3a69b7 and openzfs/spl@0ece356 on linux-3.1.10 I tried to read the xattrs on a "known problematic" file from previous issues, using The Interestingly,
Doing this a few times several minutes apart:
...shows a modest amount of activity within zfs:
Actually, these are the symptoms of #539, which I thought might have been due to #513. However this is on a freshly booted system without any NULL pointer dereferences so it looks like #513 wasn't down to #539 after all. More's the pity! Oh, I've just seen that my
I.e. we're now looking like #557. With reference to the suggested work-around in #557 of increasing
Cheers, Chris. |
Chris I believe it would have been possible (but rare) that some of the xattrs would have been only half written. That could make the subsequent getattr fail as you described and it would be persistent since it's now saved on disk. With the patch that will no longer be possible since the handle destroy before the tx is committed. |
When calling sa_update() and friends it is possible that a spill buffer will be needed to accomidate the update. When this happens a hold is taken on the new dbuf and that hold must be released before calling dmu_tx_commit(). Failing to release the hold will cause a copy of the dbuf to be made in dbuf_sync_leaf(). This is done to ensure further updates to the dbuf never sneak in to the syncing txg. This could be left to the sa_update() caller. But then the caller would need to be aware of this internal SA implementation detail. It is therefore preferable to handle this all internally in the SA implementation. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue openzfs#503 Issue openzfs#513
When calling sa_update() and friends it is possible that a spill buffer will be needed to accomidate the update. When this happens a hold is taken on the new dbuf and that hold must be released before calling dmu_tx_commit(). Failing to release the hold will cause a copy of the dbuf to be made in dbuf_sync_leaf(). This is done to ensure further updates to the dbuf never sneak in to the syncing txg. This could be left to the sa_update() caller. But then the caller would need to be aware of this internal SA implementation detail. It is therefore preferable to handle this all internally in the SA implementation. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #503 Closes #513
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest. /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 The backtrace was an infinite loop of `vdev_queue_io_to_issue()` invoking `zio_execute()` until it overran the stack. vdev_queue_io_to_issue() will ony invoke `zio_execute()` on raidz vdevs when aggregation I/Os are generated to improve aggregation continuity. These I/Os do not trigger any writes. However, it appears that they can be generated in such a way that they recurse infinitely upon return to `vdev_queue_io_to_issue()`. As a consequence, we see the number of parents by 1 each time the recursion returns to `vdev_raidz_io_start()`. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest. /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 The backtrace was an infinite loop of `vdev_queue_io_to_issue()` invoking `zio_execute()` until it overran the stack. vdev_queue_io_to_issue() will ony invoke `zio_execute()` on raidz vdevs when aggregation I/Os are generated to improve aggregation continuity. These I/Os do not trigger any writes. However, it appears that they can be generated in such a way that they recurse infinitely upon return to `vdev_queue_io_to_issue()`. As a consequence, we see the number of parents by 1 each time the recursion returns to `vdev_raidz_io_start()`. Signed-off-by: Richard Yao <richard.yao@clusterhq.com>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest. /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 The backtrace was an infinite loop of `vdev_queue_io_to_issue()` invoking `zio_execute()` until it overran the stack. vdev_queue_io_to_issue() will ony invoke `zio_execute()` on raidz vdevs when aggregation I/Os are generated to improve aggregation continuity. These I/Os do not trigger any writes. However, it appears that they can be generated in such a way that they recurse infinitely upon return to `vdev_queue_io_to_issue()`. Signed-off-by: Richard Yao <richard.yao@clusterhq.com>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
The below excerpt of a backtrace is from a ztest failure when running ZoL's ztest: /openzfs#453 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#454 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350003de0) at ../../module/zfs/vdev_queue.c:747 /openzfs#455 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350003de0) at ../../module/zfs/zio.c:2659 /openzfs#456 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1399 /openzfs#457 zio_nowait (zio=0x7f0350003de0) at ../../module/zfs/zio.c:1456 /openzfs#458 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350003a10) at ../../module/zfs/vdev_mirror.c:374 /openzfs#459 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1399 /openzfs#460 zio_nowait (zio=0x7f0350003a10) at ../../module/zfs/zio.c:1456 /openzfs#461 0x00007f03c806464c in vdev_raidz_io_start (zio=0x7f0350003380) at ../../module/zfs/vdev_raidz.c:1607 /openzfs#462 0x00007f03c807f243 in __zio_execute (zio=0x7f0350003380) at ../../module/zfs/zio.c:1399 /openzfs#463 zio_nowait (zio=0x7f0350003380) at ../../module/zfs/zio.c:1456 /openzfs#464 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002fb0) at ../../module/zfs/vdev_mirror.c:374 /openzfs#465 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1399 /openzfs#466 zio_nowait (zio=0x7f0350002fb0) at ../../module/zfs/zio.c:1456 /openzfs#467 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033957ebf0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#468 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:2707 /openzfs#469 0x00007f03c808285b in __zio_execute (zio=0x7f033957ebf0) at ../../module/zfs/zio.c:1399 /openzfs#470 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f0390001330, pio=0x7f033957ebf0) at ../../module/zfs/zio.c:547 /openzfs#471 zio_done (zio=0x7f0390001330) at ../../module/zfs/zio.c:3278 /openzfs#472 0x00007f03c808285b in __zio_execute (zio=0x7f0390001330) at ../../module/zfs/zio.c:1399 /openzfs#473 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4013a00, pio=0x7f0390001330) at ../../module/zfs/zio.c:547 /openzfs#474 zio_done (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:3278 /openzfs#475 0x00007f03c808285b in __zio_execute (zio=0x7f03b4013a00) at ../../module/zfs/zio.c:1399 /openzfs#476 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014210, pio=0x7f03b4013a00) at ../../module/zfs/zio.c:547 /openzfs#477 zio_done (zio=0x7f03b4014210) at ../../module/zfs/zio.c:3278 /openzfs#478 0x00007f03c808285b in __zio_execute (zio=0x7f03b4014210) at ../../module/zfs/zio.c:1399 /openzfs#479 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03b4014620, pio=0x7f03b4014210) at ../../module/zfs/zio.c:547 /openzfs#480 zio_done (zio=0x7f03b4014620) at ../../module/zfs/zio.c:3278 /openzfs#481 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03b4014620) at ../../module/zfs/zio.c:1399 /openzfs#482 zio_execute (zio=zio@entry=0x7f03b4014620) at ../../module/zfs/zio.c:1337 /openzfs#483 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#484 0x00007f03c806106e in vdev_queue_io (zio=zio@entry=0x7f0350002be0) at ../../module/zfs/vdev_queue.c:747 /openzfs#485 0x00007f03c80818c1 in zio_vdev_io_start (zio=0x7f0350002be0) at ../../module/zfs/zio.c:2659 /openzfs#486 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1399 /openzfs#487 zio_nowait (zio=0x7f0350002be0) at ../../module/zfs/zio.c:1456 /openzfs#488 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350002810) at ../../module/zfs/vdev_mirror.c:374 /openzfs#489 0x00007f03c807f243 in __zio_execute (zio=0x7f0350002810) at ../../module/zfs/zio.c:1399 /openzfs#490 zio_nowait (zio=0x7f0350002810) at ../../module/zfs/zio.c:1456 /openzfs#491 0x00007f03c8064593 in vdev_raidz_io_start (zio=0x7f0350001270) at ../../module/zfs/vdev_raidz.c:1591 /openzfs#492 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001270) at ../../module/zfs/zio.c:1399 /openzfs#493 zio_nowait (zio=0x7f0350001270) at ../../module/zfs/zio.c:1456 /openzfs#494 0x00007f03c805f71b in vdev_mirror_io_start (zio=0x7f0350001e60) at ../../module/zfs/vdev_mirror.c:374 /openzfs#495 0x00007f03c807f243 in __zio_execute (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1399 /openzfs#496 zio_nowait (zio=0x7f0350001e60) at ../../module/zfs/zio.c:1456 /openzfs#497 0x00007f03c805ed43 in vdev_mirror_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/vdev_mirror.c:499 /openzfs#498 0x00007f03c807a0c0 in zio_vdev_io_done (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:2707 /openzfs#499 0x00007f03c808285b in __zio_execute (zio=0x7f033a0c39c0) at ../../module/zfs/zio.c:1399 /openzfs#500 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f03a8003c00, pio=0x7f033a0c39c0) at ../../module/zfs/zio.c:547 /openzfs#501 zio_done (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:3278 /openzfs#502 0x00007f03c808285b in __zio_execute (zio=0x7f03a8003c00) at ../../module/zfs/zio.c:1399 /openzfs#503 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800c400, pio=0x7f03a8003c00) at ../../module/zfs/zio.c:547 /openzfs#504 zio_done (zio=0x7f038800c400) at ../../module/zfs/zio.c:3278 /openzfs#505 0x00007f03c808285b in __zio_execute (zio=0x7f038800c400) at ../../module/zfs/zio.c:1399 /openzfs#506 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800da00, pio=0x7f038800c400) at ../../module/zfs/zio.c:547 /openzfs#507 zio_done (zio=0x7f038800da00) at ../../module/zfs/zio.c:3278 /openzfs#508 0x00007f03c808285b in __zio_execute (zio=0x7f038800da00) at ../../module/zfs/zio.c:1399 /openzfs#509 zio_notify_parent (wait=ZIO_WAIT_DONE, zio=0x7f038800fd80, pio=0x7f038800da00) at ../../module/zfs/zio.c:547 /openzfs#510 zio_done (zio=0x7f038800fd80) at ../../module/zfs/zio.c:3278 /openzfs#511 0x00007f03c807a6d3 in __zio_execute (zio=0x7f038800fd80) at ../../module/zfs/zio.c:1399 /openzfs#512 zio_execute (zio=zio@entry=0x7f038800fd80) at ../../module/zfs/zio.c:1337 /openzfs#513 0x00007f03c8060b35 in vdev_queue_io_to_issue (vq=vq@entry=0x99f8a8) at ../../module/zfs/vdev_queue.c:706 /openzfs#514 0x00007f03c806119d in vdev_queue_io_done (zio=zio@entry=0x7f03a0010950) at ../../module/zfs/vdev_queue.c:775 /openzfs#515 0x00007f03c807a0e8 in zio_vdev_io_done (zio=0x7f03a0010950) at ../../module/zfs/zio.c:2686 /openzfs#516 0x00007f03c807a6d3 in __zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1399 /openzfs#517 zio_execute (zio=0x7f03a0010950) at ../../module/zfs/zio.c:1337 /openzfs#518 0x00007f03c7fcd0c4 in taskq_thread (arg=0x966d50) at ../../lib/libzpool/taskq.c:215 /openzfs#519 0x00007f03c7fc7937 in zk_thread_helper (arg=0x967e90) at ../../lib/libzpool/kernel.c:135 /openzfs#520 0x00007f03c78890a3 in start_thread (arg=0x7f03c2703700) at pthread_create.c:309 /openzfs#521 0x00007f03c75c50fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 This occurred when ztest was simulating a scrub under heavy I/O load. Under those circumstances, it was possible for a mix of noop I/Os for aggregation continuity and the I/O elevator to generate arbitrarily deep recursion. This patch modifies ZFS to propapage a recursion counter inside the zio_t objects such that IOs will be redispatched upon reaching a given recursion depth. We can detect long call chains and dispatch to another ZIO taskq. We cut in-line when we do this to minimize the potential for taskq exhaustion that can prevent a zio from notifying its parent. Signed-off-by: Richard Yao <ryao@gentoo.org>
…aster Merge remote-tracking branch '6.0/stage' into 'master'
With spl e05bec8, zfs 30a9524, "set xattr=sa"...
I was getting an EFAULT when trying to read the xattrs on a specific file, which first showed up as an error when using "rsync -X" to copy into the ZFS fs. I went to have a closer look at the file:
...and tried setting an xattr, which it happily did without any apparent error, but reading it back again failed:
Strace showed:
Changing the fs to "set xattr=dir" didn't help (it was then changed it back to 'sa'). I was able to successfully set xattrs on other files in the fs. E.g.:
Also:
Augh. So I've now lost the ability to reproduce the problem on that specific file. When it happens again, is there anything in particular I should be doing help track down the problem?
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