• Junxiao Bi's avatar
    md: fix deadlock causing by sysfs_notify · e1a86dbb
    Junxiao Bi authored
    The following deadlock was captured. The first process is holding 'kernfs_mutex'
    and hung by io. The io was staging in 'r1conf.pending_bio_list' of raid1 device,
    this pending bio list would be flushed by second process 'md127_raid1', but
    it was hung by 'kernfs_mutex'. Using sysfs_notify_dirent_safe() to replace
    sysfs_notify() can fix it. There were other sysfs_notify() invoked from io
    path, removed all of them.
    
     PID: 40430  TASK: ffff8ee9c8c65c40  CPU: 29  COMMAND: "probe_file"
      #0 [ffffb87c4df37260] __schedule at ffffffff9a8678ec
      #1 [ffffb87c4df372f8] schedule at ffffffff9a867f06
      #2 [ffffb87c4df37310] io_schedule at ffffffff9a0c73e6
      #3 [ffffb87c4df37328] __dta___xfs_iunpin_wait_3443 at ffffffffc03a4057 [xfs]
      #4 [ffffb87c4df373a0] xfs_iunpin_wait at ffffffffc03a6c79 [xfs]
      #5 [ffffb87c4df373b0] __dta_xfs_reclaim_inode_3357 at ffffffffc039a46c [xfs]
      #6 [ffffb87c4df37400] xfs_reclaim_inodes_ag at ffffffffc039a8b6 [xfs]
      #7 [ffffb87c4df37590] xfs_reclaim_inodes_nr at ffffffffc039bb33 [xfs]
      #8 [ffffb87c4df375b0] xfs_fs_free_cached_objects at ffffffffc03af0e9 [xfs]
      #9 [ffffb87c4df375c0] super_cache_scan at ffffffff9a287ec7
     #10 [ffffb87c4df37618] shrink_slab at ffffffff9a1efd93
     #11 [ffffb87c4df37700] shrink_node at ffffffff9a1f5968
     #12 [ffffb87c4df37788] do_try_to_free_pages at ffffffff9a1f5ea2
     #13 [ffffb87c4df377f0] try_to_free_mem_cgroup_pages at ffffffff9a1f6445
     #14 [ffffb87c4df37880] try_charge at ffffffff9a26cc5f
     #15 [ffffb87c4df37920] memcg_kmem_charge_memcg at ffffffff9a270f6a
     #16 [ffffb87c4df37958] new_slab at ffffffff9a251430
     #17 [ffffb87c4df379c0] ___slab_alloc at ffffffff9a251c85
     #18 [ffffb87c4df37a80] __slab_alloc at ffffffff9a25635d
     #19 [ffffb87c4df37ac0] kmem_cache_alloc at ffffffff9a251f89
     #20 [ffffb87c4df37b00] alloc_inode at ffffffff9a2a2b10
     #21 [ffffb87c4df37b20] iget_locked at ffffffff9a2a4854
     #22 [ffffb87c4df37b60] kernfs_get_inode at ffffffff9a311377
     #23 [ffffb87c4df37b80] kernfs_iop_lookup at ffffffff9a311e2b
     #24 [ffffb87c4df37ba8] lookup_slow at ffffffff9a290118
     #25 [ffffb87c4df37c10] walk_component at ffffffff9a291e83
     #26 [ffffb87c4df37c78] path_lookupat at ffffffff9a293619
     #27 [ffffb87c4df37cd8] filename_lookup at ffffffff9a2953af
     #28 [ffffb87c4df37de8] user_path_at_empty at ffffffff9a295566
     #29 [ffffb87c4df37e10] vfs_statx at ffffffff9a289787
     #30 [ffffb87c4df37e70] SYSC_newlstat at ffffffff9a289d5d
     #31 [ffffb87c4df37f18] sys_newlstat at ffffffff9a28a60e
     #32 [ffffb87c4df37f28] do_syscall_64 at ffffffff9a003949
     #33 [ffffb87c4df37f50] entry_SYSCALL_64_after_hwframe at ffffffff9aa001ad
         RIP: 00007f617a5f2905  RSP: 00007f607334f838  RFLAGS: 00000246
         RAX: ffffffffffffffda  RBX: 00007f6064044b20  RCX: 00007f617a5f2905
         RDX: 00007f6064044b20  RSI: 00007f6064044b20  RDI: 00007f6064005890
         RBP: 00007f6064044aa0   R8: 0000000000000030   R9: 000000000000011c
         R10: 0000000000000013  R11: 0000000000000246  R12: 00007f606417e6d0
         R13: 00007f6064044aa0  R14: 00007f6064044b10  R15: 00000000ffffffff
         ORIG_RAX: 0000000000000006  CS: 0033  SS: 002b
    
     PID: 927    TASK: ffff8f15ac5dbd80  CPU: 42  COMMAND: "md127_raid1"
      #0 [ffffb87c4df07b28] __schedule at ffffffff9a8678ec
      #1 [ffffb87c4df07bc0] schedule at ffffffff9a867f06
      #2 [ffffb87c4df07bd8] schedule_preempt_disabled at ffffffff9a86825e
      #3 [ffffb87c4df07be8] __mutex_lock at ffffffff9a869bcc
      #4 [ffffb87c4df07ca0] __mutex_lock_slowpath at ffffffff9a86a013
      #5 [ffffb87c4df07cb0] mutex_lock at ffffffff9a86a04f
      #6 [ffffb87c4df07cc8] kernfs_find_and_get_ns at ffffffff9a311d83
      #7 [ffffb87c4df07cf0] sysfs_notify at ffffffff9a314b3a
      #8 [ffffb87c4df07d18] md_update_sb at ffffffff9a688696
      #9 [ffffb87c4df07d98] md_update_sb at ffffffff9a6886d5
     #10 [ffffb87c4df07da8] md_check_recovery at ffffffff9a68ad9c
     #11 [ffffb87c4df07dd0] raid1d at ffffffffc01f0375 [raid1]
     #12 [ffffb87c4df07ea0] md_thread at ffffffff9a680348
     #13 [ffffb87c4df07f08] kthread at ffffffff9a0b8005
     #14 [ffffb87c4df07f50] ret_from_fork at ffffffff9aa00344
    Signed-off-by: default avatarJunxiao Bi <junxiao.bi@oracle.com>
    Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
    e1a86dbb
md.c 258 KB