Commits
Guoqing Jiang committed 7bcda7149dd
md-cluster: introduce dlm_lock_sync_interruptible to fix tasks hang When some node leaves cluster, then it's bitmap need to be synced by another node, so "md*_recover" thread is triggered for the purpose. However, with below steps. we can find tasks hang happened either in B or C. 1. Node A create a resyncing cluster raid1, assemble it in other two nodes (B and C). 2. stop array in B and C. 3. stop array in A. linux44:~ # ps aux|grep md|grep D root 5938 0.0 0.1 19852 1964 pts/0 D+ 14:52 0:00 mdadm -S md0 root 5939 0.0 0.0 0 0 ? D 14:52 0:00 [md0_recover] linux44:~ # cat /proc/5939/stack [<ffffffffa04cf321>] dlm_lock_sync+0x71/0x90 [md_cluster] [<ffffffffa04d0705>] recover_bitmaps+0x125/0x220 [md_cluster] [<ffffffffa052105d>] md_thread+0x16d/0x180 [md_mod] [<ffffffff8107ad94>] kthread+0xb4/0xc0 [<ffffffff8152a518>] ret_from_fork+0x58/0x90 linux44:~ # cat /proc/5938/stack [<ffffffff8107afde>] kthread_stop+0x6e/0x120 [<ffffffffa0519da0>] md_unregister_thread+0x40/0x80 [md_mod] [<ffffffffa04cfd20>] leave+0x70/0x120 [md_cluster] [<ffffffffa0525e24>] md_cluster_stop+0x14/0x30 [md_mod] [<ffffffffa05269ab>] bitmap_free+0x14b/0x150 [md_mod] [<ffffffffa0523f3b>] do_md_stop+0x35b/0x5a0 [md_mod] [<ffffffffa0524e83>] md_ioctl+0x873/0x1590 [md_mod] [<ffffffff81288464>] blkdev_ioctl+0x214/0x7d0 [<ffffffff811dd3dd>] block_ioctl+0x3d/0x40 [<ffffffff811b92d4>] do_vfs_ioctl+0x2d4/0x4b0 [<ffffffff811b9538>] SyS_ioctl+0x88/0xa0 [<ffffffff8152a5c9>] system_call_fastpath+0x16/0x1b The problem is caused by recover_bitmaps can't reliably abort when the thread is unregistered. So dlm_lock_sync_interruptible is introduced to detect the thread's situation to fix the problem. Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Guoqing Jiang <gqjiang@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>