1. 01 Dec, 2020 22 commits
  2. 30 Nov, 2020 8 commits
    • Jens Axboe's avatar
      Merge branch 'md-next' of... · 48332ff2
      Jens Axboe authored
      Merge branch 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md into for-5.11/drivers
      
      Pull MD changes from Song:
      
      "Summary:
       1. Fix race condition in md_ioctl(), by Dae R. Jeong;
       2. Initialize read_slot properly for raid10, by Kevin Vigor;
       3. Code cleanup, by Pankaj Gupta;
       4. md-cluster resync/reshape fix, by Zhao Heming."
      
      * 'md-next' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
        md/cluster: fix deadlock when node is doing resync job
        md/cluster: block reshape with remote resync job
        md: use current request time as base for ktime comparisons
        md: add comments in md_flush_request()
        md: improve variable names in md_flush_request()
        md/raid10: initialize r10_bio->read_slot before use.
        md: fix a warning caused by a race between concurrent md_ioctl()s
      48332ff2
    • Zhao Heming's avatar
      md/cluster: fix deadlock when node is doing resync job · bca5b065
      Zhao Heming authored
      md-cluster uses MD_CLUSTER_SEND_LOCK to make node can exclusively send msg.
      During sending msg, node can concurrently receive msg from another node.
      When node does resync job, grab token_lockres:EX may trigger a deadlock:
      ```
      nodeA                       nodeB
      --------------------     --------------------
      a.
      send METADATA_UPDATED
      held token_lockres:EX
                               b.
                               md_do_sync
                                resync_info_update
                                  send RESYNCING
                                   + set MD_CLUSTER_SEND_LOCK
                                   + wait for holding token_lockres:EX
      
                               c.
                               mdadm /dev/md0 --remove /dev/sdg
                                + held reconfig_mutex
                                + send REMOVE
                                   + wait_event(MD_CLUSTER_SEND_LOCK)
      
                               d.
                               recv_daemon //METADATA_UPDATED from A
                                process_metadata_update
                                 + (mddev_trylock(mddev) ||
                                    MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD)
                                   //this time, both return false forever
      ```
      Explaination:
      a. A send METADATA_UPDATED
         This will block another node to send msg
      
      b. B does sync jobs, which will send RESYNCING at intervals.
         This will be block for holding token_lockres:EX lock.
      
      c. B do "mdadm --remove", which will send REMOVE.
         This will be blocked by step <b>: MD_CLUSTER_SEND_LOCK is 1.
      
      d. B recv METADATA_UPDATED msg, which send from A in step <a>.
         This will be blocked by step <c>: holding mddev lock, it makes
         wait_event can't hold mddev lock. (btw,
         MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD keep ZERO in this scenario.)
      
      There is a similar deadlock in commit 0ba95977
      ("md-cluster: use sync way to handle METADATA_UPDATED msg")
      In that commit, step c is "update sb". This patch step c is
      "mdadm --remove".
      
      For fixing this issue, we can refer the solution of function:
      metadata_update_start. Which does the same grab lock_token action.
      lock_comm can use the same steps to avoid deadlock. By moving
      MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD from lock_token to lock_comm.
      It enlarge a little bit window of MD_CLUSTER_HOLDING_MUTEX_FOR_RECVD,
      but it is safe & can break deadlock.
      
      Repro steps (I only triggered 3 times with hundreds tests):
      
      two nodes share 3 iSCSI luns: sdg/sdh/sdi. Each lun size is 1GB.
      ```
      ssh root@node2 "mdadm -S --scan"
      mdadm -S --scan
      for i in {g,h,i};do dd if=/dev/zero of=/dev/sd$i oflag=direct bs=1M \
      count=20; done
      
      mdadm -C /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sdg /dev/sdh \
       --bitmap-chunk=1M
      ssh root@node2 "mdadm -A /dev/md0 /dev/sdg /dev/sdh"
      
      sleep 5
      
      mkfs.xfs /dev/md0
      mdadm --manage --add /dev/md0 /dev/sdi
      mdadm --wait /dev/md0
      mdadm --grow --raid-devices=3 /dev/md0
      
      mdadm /dev/md0 --fail /dev/sdg
      mdadm /dev/md0 --remove /dev/sdg
      mdadm --grow --raid-devices=2 /dev/md0
      ```
      
      test script will hung when executing "mdadm --remove".
      
      ```
       # dump stacks by "echo t > /proc/sysrq-trigger"
      md0_cluster_rec D    0  5329      2 0x80004000
      Call Trace:
       __schedule+0x1f6/0x560
       ? _cond_resched+0x2d/0x40
       ? schedule+0x4a/0xb0
       ? process_metadata_update.isra.0+0xdb/0x140 [md_cluster]
       ? wait_woken+0x80/0x80
       ? process_recvd_msg+0x113/0x1d0 [md_cluster]
       ? recv_daemon+0x9e/0x120 [md_cluster]
       ? md_thread+0x94/0x160 [md_mod]
       ? wait_woken+0x80/0x80
       ? md_congested+0x30/0x30 [md_mod]
       ? kthread+0x115/0x140
       ? __kthread_bind_mask+0x60/0x60
       ? ret_from_fork+0x1f/0x40
      
      mdadm           D    0  5423      1 0x00004004
      Call Trace:
       __schedule+0x1f6/0x560
       ? __schedule+0x1fe/0x560
       ? schedule+0x4a/0xb0
       ? lock_comm.isra.0+0x7b/0xb0 [md_cluster]
       ? wait_woken+0x80/0x80
       ? remove_disk+0x4f/0x90 [md_cluster]
       ? hot_remove_disk+0xb1/0x1b0 [md_mod]
       ? md_ioctl+0x50c/0xba0 [md_mod]
       ? wait_woken+0x80/0x80
       ? blkdev_ioctl+0xa2/0x2a0
       ? block_ioctl+0x39/0x40
       ? ksys_ioctl+0x82/0xc0
       ? __x64_sys_ioctl+0x16/0x20
       ? do_syscall_64+0x5f/0x150
       ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
      
      md0_resync      D    0  5425      2 0x80004000
      Call Trace:
       __schedule+0x1f6/0x560
       ? schedule+0x4a/0xb0
       ? dlm_lock_sync+0xa1/0xd0 [md_cluster]
       ? wait_woken+0x80/0x80
       ? lock_token+0x2d/0x90 [md_cluster]
       ? resync_info_update+0x95/0x100 [md_cluster]
       ? raid1_sync_request+0x7d3/0xa40 [raid1]
       ? md_do_sync.cold+0x737/0xc8f [md_mod]
       ? md_thread+0x94/0x160 [md_mod]
       ? md_congested+0x30/0x30 [md_mod]
       ? kthread+0x115/0x140
       ? __kthread_bind_mask+0x60/0x60
       ? ret_from_fork+0x1f/0x40
      ```
      
      At last, thanks for Xiao's solution.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarZhao Heming <heming.zhao@suse.com>
      Suggested-by: default avatarXiao Ni <xni@redhat.com>
      Reviewed-by: default avatarXiao Ni <xni@redhat.com>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      bca5b065
    • Zhao Heming's avatar
      md/cluster: block reshape with remote resync job · a8da01f7
      Zhao Heming authored
      Reshape request should be blocked with ongoing resync job. In cluster
      env, a node can start resync job even if the resync cmd isn't executed
      on it, e.g., user executes "mdadm --grow" on node A, sometimes node B
      will start resync job. However, current update_raid_disks() only check
      local recovery status, which is incomplete. As a result, we see user will
      execute "mdadm --grow" successfully on local, while the remote node deny
      to do reshape job when it doing resync job. The inconsistent handling
      cause array enter unexpected status. If user doesn't observe this issue
      and continue executing mdadm cmd, the array doesn't work at last.
      
      Fix this issue by blocking reshape request. When node executes "--grow"
      and detects ongoing resync, it should stop and report error to user.
      
      The following script reproduces the issue with ~100% probability.
      (two nodes share 3 iSCSI luns: sdg/sdh/sdi. Each lun size is 1GB)
      ```
       # on node1, node2 is the remote node.
      ssh root@node2 "mdadm -S --scan"
      mdadm -S --scan
      for i in {g,h,i};do dd if=/dev/zero of=/dev/sd$i oflag=direct bs=1M \
      count=20; done
      
      mdadm -C /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sdg /dev/sdh
      ssh root@node2 "mdadm -A /dev/md0 /dev/sdg /dev/sdh"
      
      sleep 5
      
      mdadm --manage --add /dev/md0 /dev/sdi
      mdadm --wait /dev/md0
      mdadm --grow --raid-devices=3 /dev/md0
      
      mdadm /dev/md0 --fail /dev/sdg
      mdadm /dev/md0 --remove /dev/sdg
      mdadm --grow --raid-devices=2 /dev/md0
      ```
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarZhao Heming <heming.zhao@suse.com>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      a8da01f7
    • Pankaj Gupta's avatar
      md: use current request time as base for ktime comparisons · a23f2aae
      Pankaj Gupta authored
      Request coalescing logic uses 'prev_flush_start' as base to
      compare the current request start time. 'prev_flush_start' is
      updated in other context.
      
      This patch changes this by using ktime comparison base to
      'req_start' for better readability of code.
      Signed-off-by: default avatarPankaj Gupta <pankaj.gupta@cloud.ionos.com>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      a23f2aae
    • Pankaj Gupta's avatar
      md: add comments in md_flush_request() · 204d1a64
      Pankaj Gupta authored
      Request coalescing logic is dependent on flush time update in other
      context. This patch adds comments to understand the code flow better.
      Signed-off-by: default avatarPankaj Gupta <pankaj.gupta@cloud.ionos.com>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      204d1a64
    • Pankaj Gupta's avatar
      md: improve variable names in md_flush_request() · 81ba3c24
      Pankaj Gupta authored
      This patch improves readability by using better variable names
      in flush request coalescing logic.
      Signed-off-by: default avatarPankaj Gupta <pankaj.gupta@cloud.ionos.com>
      Reviewed-by: default avatarPaul Menzel <pmenzel@molgen.mpg.de>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      81ba3c24
    • Kevin Vigor's avatar
      md/raid10: initialize r10_bio->read_slot before use. · 93decc56
      Kevin Vigor authored
      In __make_request() a new r10bio is allocated and passed to
      raid10_read_request(). The read_slot member of the bio is not
      initialized, and the raid10_read_request() uses it to index an
      array. This leads to occasional panics.
      
      Fix by initializing the field to invalid value and checking for
      valid value in raid10_read_request().
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarKevin Vigor <kvigor@gmail.com>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      93decc56
    • Dae R. Jeong's avatar
      md: fix a warning caused by a race between concurrent md_ioctl()s · c731b84b
      Dae R. Jeong authored
      Syzkaller reports a warning as belows.
      WARNING: CPU: 0 PID: 9647 at drivers/md/md.c:7169
      ...
      Call Trace:
      ...
      RIP: 0010:md_ioctl+0x4017/0x5980 drivers/md/md.c:7169
      RSP: 0018:ffff888096027950 EFLAGS: 00010293
      RAX: ffff88809322c380 RBX: 0000000000000932 RCX: ffffffff84e266f2
      RDX: 0000000000000000 RSI: ffffffff84e299f7 RDI: 0000000000000007
      RBP: ffff888096027bc0 R08: ffff88809322c380 R09: ffffed101341a482
      R10: ffff888096027940 R11: ffff88809a0d240f R12: 0000000000000932
      R13: ffff8880a2c14100 R14: ffff88809a0d2268 R15: ffff88809a0d2408
       __blkdev_driver_ioctl block/ioctl.c:304 [inline]
       blkdev_ioctl+0xece/0x1c10 block/ioctl.c:606
       block_ioctl+0xee/0x130 fs/block_dev.c:1930
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:509 [inline]
       do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
       ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
       do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      This is caused by a race between two concurrenct md_ioctl()s closing
      the array.
      CPU1 (md_ioctl())                   CPU2 (md_ioctl())
      ------                              ------
      set_bit(MD_CLOSING, &mddev->flags);
      did_set_md_closing = true;
                                          WARN_ON_ONCE(test_bit(MD_CLOSING,
                                                  &mddev->flags));
      if(did_set_md_closing)
          clear_bit(MD_CLOSING, &mddev->flags);
      
      Fix the warning by returning immediately if the MD_CLOSING bit is set
      in &mddev->flags which indicates that the array is being closed.
      
      Fixes: 065e519e ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop")
      Reported-by: syzbot+1e46a0864c1a6e9bd3d8@syzkaller.appspotmail.com
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarDae R. Jeong <dae.r.jeong@kaist.ac.kr>
      Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
      c731b84b
  3. 16 Nov, 2020 10 commits