I've been looking at a hang that was reported off-list, and I believe I
found the cause. I'm still waiting for confirmation on whether the
patch does fix the problem, but I wanted to distribute the patch in case
anyone else is seeing a similar hang. It looks like the problem is in
kernels from 2.6.17 to the present.
Thanks,
Shaggy
JFS: Fix race waking up jfsIO kernel thread
It's possible for a journal I/O request to be added to the log_redrive
queue and the jfsIO thread to be awakened after the thread releases
log_redrive_lock but before it sets its state to TASK_INTERRUPTIBLE.
The jfsIO thread should set its state before giving up the spinlock, so
the waking thread will really wake it.
Signed-off-by: Dave Kleikamp <shaggy@xxxxxxxxxxxxxxxxxx>
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index ff7f1be..16c6268 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -2354,12 +2354,13 @@ int jfsIOWait(void *arg)
lbmStartIO(bp);
spin_lock_irq(&log_redrive_lock);
}
- spin_unlock_irq(&log_redrive_lock);
if (freezing(current)) {
+ spin_unlock_irq(&log_redrive_lock);
refrigerator();
} else {
set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&log_redrive_lock);
schedule();
__set_current_state(TASK_RUNNING);
}
--
David Kleikamp
IBM Linux Technology Center
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