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| author |   Guoqing Jiang <gqjiang@suse.com> | 2017-10-09 10:32:48 +0800 |
|---|---|---|
| committer |   Shaohua Li <shli@fb.com> | 2017-10-08 20:36:39 -0700 |
| commit | d1d90147c9680aaec4a5757932c2103c42c9c23b (patch) | |
| tree | 20986021b290c8c30375b90020a5c7bf51de4fc5 /drivers/md/md.c | |
| parent | md: fix deadlock error in recent patch. (diff) | |
| download | linux-dev-d1d90147c9680aaec4a5757932c2103c42c9c23b.tar.xz linux-dev-d1d90147c9680aaec4a5757932c2103c42c9c23b.zip | |
md: always set THREAD_WAKEUP and wake up wqueue if thread existed
Since commit 4ad23a976413 ("MD: use per-cpu counter for writes_pending"),
the wait_queue is only got invoked if THREAD_WAKEUP is not set previously.
With above change, I can see process_metadata_update could always hang on
the wait queue, because mddev->thread could stay on 'D' status and the
THREAD_WAKEUP flag is not cleared since there are lots of place to wake up
mddev->thread. Then deadlock happened as follows:
linux175:~ # ps aux|grep md|grep D
root 20117 0.0 0.0 0 0 ? D 03:45 0:00 [md0_raid1]
root 20125 0.0 0.0 0 0 ? D 03:45 0:00 [md0_cluster_rec]
linux175:~ # cat /proc/20117/stack
[<ffffffffa0635604>] dlm_lock_sync+0x94/0xd0 [md_cluster]
[<ffffffffa0635674>] lock_token+0x34/0xd0 [md_cluster]
[<ffffffffa0635804>] metadata_update_start+0x64/0x110 [md_cluster]
[<ffffffffa04d985b>] md_update_sb.part.58+0x9b/0x860 [md_mod]
[<ffffffffa04da035>] md_update_sb+0x15/0x30 [md_mod]
[<ffffffffa04dc066>] md_check_recovery+0x266/0x490 [md_mod]
[<ffffffffa06450e2>] raid1d+0x42/0x810 [raid1]
[<ffffffffa04d2252>] md_thread+0x122/0x150 [md_mod]
[<ffffffff81091741>] kthread+0x101/0x140
linux175:~ # cat /proc/20125/stack
[<ffffffffa0636679>] recv_daemon+0x3f9/0x5c0 [md_cluster]
[<ffffffffa04d2252>] md_thread+0x122/0x150 [md_mod]
[<ffffffff81091741>] kthread+0x101/0x140
So let's revert the part of code in the commit to resovle the problem since
we can't get lots of benefits of previous change.
Fixes: 4ad23a976413 ("MD: use per-cpu counter for writes_pending")
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/md.c')
| -rw-r--r-- | drivers/md/md.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 8b2eb0f4122f..707471e3cb01 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7468,8 +7468,8 @@ void md_wakeup_thread(struct md_thread *thread) { if (thread) { pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm); - if (!test_and_set_bit(THREAD_WAKEUP, &thread->flags)) - wake_up(&thread->wqueue); + set_bit(THREAD_WAKEUP, &thread->flags); + wake_up(&thread->wqueue); } } EXPORT_SYMBOL(md_wakeup_thread); |