Commits on Sep 5, 2024

1. Introduce vmcore creation notification to kdump …

   Motivation
   ==========
   
   People may forget to recheck to ensure kdump works, which as a result, a
   possibility of no vmcores generated after a real system crash. It is
   unexpected for kdump.
   
   It is highly recommended people to recheck kdump after any system
   modification, such as:
   
   a. after kernel patching or whole yum update, as it might break something
      on which kdump is dependent, maybe due to introduction of any new bug etc.
   b. after any change at hardware level, maybe storage, networking,
      firmware upgrading etc.
   c. after implementing any new application, like which involves 3rd party modules
      etc.
   
   Though these exceed the range of kdump, however a simple vmcore creation
   status notification is good to have for now.
   
   Design
   ======
   
   Kdump currently will check any relating files/fs/drivers modified before
   determine if initrd should rebuild when (re)start. A rebuild is an
   indicator of such modification, and kdump need to be rechecked. This will
   clear the vmcore creation status specified in $VMCORE_CREATION_STATUS.
   
   Vmcore creation check will happen at "kdumpctl (re)start/status", and will
   report the creation success/fail status to users. A "success" status indicates
   previously there has been a vmcore successfully generated based on the current
   env, so it is more likely a vmcore will be generated later when real crash
   happens; A "fail" status indicates previously there was no vmcore
   generated, or has been a vmcore creation failed based on current env. User
   should check the 2nd kernel log or the kexec-dmesg.log for the failing reason.
   
   $VMCORE_CREATION_STATUS is used for recording the vmcore creation status of
   the current env. The format will be like:
   
      success 1718682002
   
   Which means, there has been a vmcore generated successfully at this
   timestamp for the current env.
   
   Usage
   =====
   
   [root@localhost ~]# kdumpctl restart
   kdump: kexec: unloaded kdump kernel
   kdump: Stopping kdump: [OK]
   kdump: kexec: loaded kdump kernel
   kdump: Starting kdump: [OK]
   kdump: Notice: No vmcore creation test performed!
   
   [root@localhost ~]# kdumpctl test
   
   [root@localhost ~]# kdumpctl status
   kdump: Kdump is operational
   kdump: Notice: Last successful vmcore creation on Tue Jun 18 16:39:10 CST 2024
   
   [root@localhost ~]# kdumpctl restart
   kdump: kexec: unloaded kdump kernel
   kdump: Stopping kdump: [OK]
   kdump: kexec: loaded kdump kernel
   kdump: Starting kdump: [OK]
   kdump: Notice: Last successful vmcore creation on Tue Jun 18 16:39:10 CST 2024
   
   The notification for kdumpctl (re)start/status can be disabled by
   setting VMCORE_CREATION_NOTIFICATION in /etc/sysconfig/kdump
   
   ===
   
   v3 -> v2:
   Always mount
   $VMCORE_CREATION_STATUS(/var/crash/vmcore-creation.status)'s device for
   2nd kernel, in case /var is a seperate device than rootfs's device.
   
   v4 -> v3:
   Add "kdumpctl test" as the entrance for performing the kdump test.
   
   v5 -> v4:
   Fix the mounting failure issue in fadump.
   
   v6 -> v5:
   Add new argument as customized mount point for add_mount/to_mount.
   
   v7 -> v6:
   a. Code refactoring based on Philipp's suggestion.
   b. Only mount $VMCORE_CREATION_STATUS(/var/crash/vmcore-creation.status)'s
      device when needed.
   c. Add "--force" option for "kdumpctl test", to support the automation test
      script QE may perform.
   d. Add check in "kdumpctl test" that $VMCORE_CREATION_STATUS can only be on
      local drive.
   
   v8 -> v7:
   a. Rebased the patch on top of upstream commit e2b8463.
   b. Code refactoring based on Philipp's suggestion.
   c. Updated the "test" entry of kdumpctl.8.
   
   Signed-off-by: Tao Liu <ltao@redhat.com>

   

   liutgnu committed Sep 5, 2024
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