diff --git a/include/linux/mm_compat.h b/include/linux/mm_compat.h index 37c9b087..2e52cf6a 100644 --- a/include/linux/mm_compat.h +++ b/include/linux/mm_compat.h @@ -311,4 +311,11 @@ fn ## _scan_objects(struct shrinker *shrink, struct shrink_control *sc) \ #error "Unknown shrinker callback" #endif +#if defined(HAVE_SPLIT_SHRINKER_CALLBACK) +typedef unsigned long spl_shrinker_t; +#else +typedef int spl_shrinker_t; +#define SHRINK_STOP (-1) +#endif + #endif /* SPL_MM_COMPAT_H */ diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c index 8c0e62e5..fc71a37b 100644 --- a/module/spl/spl-kmem.c +++ b/module/spl/spl-kmem.c @@ -2126,14 +2126,24 @@ EXPORT_SYMBOL(spl_kmem_cache_free); * report that they contain unused objects. Because of this we only * register one shrinker function in the shim layer for all slab caches. * We always attempt to shrink all caches when this generic shrinker - * is called. The shrinker should return the number of free objects - * in the cache when called with nr_to_scan == 0 but not attempt to - * free any objects. When nr_to_scan > 0 it is a request that nr_to_scan - * objects should be freed, which differs from Solaris semantics. - * Solaris semantics are to free all available objects which may (and - * probably will) be more objects than the requested nr_to_scan. + * is called. + * + * If sc->nr_to_scan is zero, the caller is requesting a query of the + * number of objects which can potentially be freed. If it is nonzero, + * the request is to free that many objects. + * + * Linux kernels >= 3.12 have the count_objects and scan_objects callbacks + * in struct shrinker and also require the shrinker to return the number + * of objects freed. + * + * Older kernels require the shrinker to return the number of freeable + * objects following the freeing of nr_to_free. + * + * Linux semantics differ from those under Solaris, which are to + * free all available objects which may (and probably will) be more + * objects than the requested nr_to_scan. */ -static int +static spl_shrinker_t __spl_kmem_cache_generic_shrinker(struct shrinker *shrink, struct shrink_control *sc) { @@ -2142,17 +2152,22 @@ __spl_kmem_cache_generic_shrinker(struct shrinker *shrink, down_read(&spl_kmem_cache_sem); list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) { - if (sc->nr_to_scan) + if (sc->nr_to_scan) { +#ifdef HAVE_SPLIT_SHRINKER_CALLBACK + uint64_t oldalloc = skc->skc_obj_alloc; spl_kmem_cache_reap_now(skc, MAX(sc->nr_to_scan >> fls64(skc->skc_slab_objs), 1)); - - /* - * Presume everything alloc'ed is reclaimable, this ensures - * we are called again with nr_to_scan > 0 so can try and - * reclaim. The exact number is not important either so - * we forgo taking this already highly contented lock. - */ - alloc += skc->skc_obj_alloc; + if (oldalloc > skc->skc_obj_alloc) + alloc += oldalloc - skc->skc_obj_alloc; +#else + spl_kmem_cache_reap_now(skc, + MAX(sc->nr_to_scan >> fls64(skc->skc_slab_objs), 1)); + alloc += skc->skc_obj_alloc; +#endif /* HAVE_SPLIT_SHRINKER_CALLBACK */ + } else { + /* Request to query number of freeable objects */ + alloc += skc->skc_obj_alloc; + } } up_read(&spl_kmem_cache_sem); @@ -2163,7 +2178,7 @@ __spl_kmem_cache_generic_shrinker(struct shrinker *shrink, * system to thrash. */ if ((spl_kmem_cache_reclaim & KMC_RECLAIM_ONCE) && sc->nr_to_scan) - return (-1); + return (SHRINK_STOP); return MAX((alloc * sysctl_vfs_cache_pressure) / 100, 0); } @@ -2274,7 +2289,7 @@ spl_kmem_reap(void) sc.nr_to_scan = KMC_REAP_CHUNK; sc.gfp_mask = GFP_KERNEL; - __spl_kmem_cache_generic_shrinker(NULL, &sc); + (void) __spl_kmem_cache_generic_shrinker(NULL, &sc); } EXPORT_SYMBOL(spl_kmem_reap); diff --git a/module/splat/splat-linux.c b/module/splat/splat-linux.c index ce809e64..483e0447 100644 --- a/module/splat/splat-linux.c +++ b/module/splat/splat-linux.c @@ -97,11 +97,13 @@ SPL_SHRINKER_DECLARE(splat_linux_shrinker, splat_linux_shrinker_fn, 1); static unsigned long splat_linux_shrinker_size = 0; static struct file *splat_linux_shrinker_file = NULL; -static int +static spl_shrinker_t __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc) { static int failsafe = 0; static unsigned long last_splat_linux_shrinker_size = 0; + unsigned long size; + spl_shrinker_t count; /* * shrinker_size can only decrease or stay the same between callbacks @@ -114,13 +116,21 @@ __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc) last_splat_linux_shrinker_size = splat_linux_shrinker_size; if (sc->nr_to_scan) { - splat_linux_shrinker_size = splat_linux_shrinker_size - - MIN(sc->nr_to_scan, splat_linux_shrinker_size); + size = MIN(sc->nr_to_scan, splat_linux_shrinker_size); + splat_linux_shrinker_size -= size; splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST3_NAME, "Reclaimed %lu objects, size now %lu\n", - sc->nr_to_scan, splat_linux_shrinker_size); + size, splat_linux_shrinker_size); + +#ifdef HAVE_SPLIT_SHRINKER_CALLBACK + count = size; +#else + count = splat_linux_shrinker_size; +#endif /* HAVE_SPLIT_SHRINKER_CALLBACK */ + } else { + count = splat_linux_shrinker_size; splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST3_NAME, "Cache size is %lu\n", splat_linux_shrinker_size); } @@ -130,7 +140,7 @@ __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc) splat_vprint(splat_linux_shrinker_file, SPLAT_LINUX_TEST3_NAME, "Far more calls than expected (%d), size now %lu\n", failsafe, splat_linux_shrinker_size); - return -1; + return (SHRINK_STOP); } else { /* * We only increment failsafe if it doesn't trigger. This @@ -142,7 +152,7 @@ __splat_linux_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc) /* Shrinker has run, so signal back to test. */ wake_up(&shrinker_wait); - return (int)splat_linux_shrinker_size; + return (count); } SPL_SHRINKER_CALLBACK_WRAPPER(splat_linux_shrinker_fn);