Messages in this thread | | | Date | Sun, 06 Jun 2010 23:23:36 -0500 | From | Eric Sandeen <> | Subject | Re: 2.6.34 echo j > /proc/sysrq-trigger causes inifnite unfreeze/Thaw event |
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Dave Chinner wrote: > On Thu, Jun 03, 2010 at 11:30:30PM -0600, Jeffrey Merkey wrote: >> causes the FS Thaw stuff in fs/buffer.c to enter an infinite loop >> filling the /var/log/messages with junk and causing the hard drive to >> crank away endlessly. > > Hmmm, looks pretty obvious what the 2.6.34 bug is: > > while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) > printk(KERN_WARNING "Emergency Thaw on %s\n", > bdevname(sb->s_bdev, b)); > > thaw_bdev() returns 0 on success or not frozen, and returns non-zero > only if the unfreeze failed. Looks like it was broken from the start > to me.
thaw_bdev() used to return -EINVAL for not-frozen, but it no longer does. Seems commit 4504230a dropped this:
- if (!bdev->bd_fsfreeze_count) { - mutex_unlock(&bdev->bd_fsfreeze_mutex); - return -EINVAL; - }
in favor of this:
+ int error = -EINVAL; ... + if (!bdev->bd_fsfreeze_count) + goto out_unlock; ... +out_unlock: mutex_unlock(&bdev->bd_fsfreeze_mutex); return 0;
and now we return 0 for a thaw of a non-frozen bdev .... this breaks the loop in the emergency thaw-er (which was just supposed to work its way through nested freezes, when I wrote it)
-Eric
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