Re: 3.4.4-rt13: btrfs + xfstests 006 = BOOM.. and a bonus rt_mutex deadlock report for absolutely free!
From: Mike Galbraith <hidden>
Date: 2012-07-12 13:37:50
Also in:
linux-fsdevel, lkml
On Thu, 2012-07-12 at 15:31 +0200, Thomas Gleixner wrote:
On Thu, 12 Jul 2012, Mike Galbraith wrote:quoted
On Thu, 2012-07-12 at 13:43 +0200, Thomas Gleixner wrote:quoted
rawlock points to ...968 and the node_list to ...970. struct rt_mutex { raw_spinlock_t wait_lock; struct plist_head wait_list; The raw_lock pointer of the plist_head is initialized in __rt_mutex_init() so it points to wait_lock. Can you check the offset of wait_list vs. the rt_mutex itself? I wouldn't be surprised if it's exactly 8 bytes. And then this thing looks like a copied lock with stale pointers to hell. Eew.crash> struct rt_mutex -o struct rt_mutex { [0] raw_spinlock_t wait_lock; [8] struct plist_head wait_list;Bingo, that makes it more likely that this is caused by copying w/o initializing the lock and then freeing the original structure. A quick check for memcpy finds that __btrfs_close_devices() does a memcpy of btrfs_device structs w/o initializing the lock in the new copy, but I have no idea whether that's the place we are looking for.
Cool, you found one, thanks! I'm setting boobytraps. Um, correction, box says I'm setting _buggy_ boobytraps :) Tomorrow-man will test this and frob traps anew.
quoted hunk ↗ jump to hunk
Thanks, tglxdiff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 43baaf0..06c8ced 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c@@ -512,6 +512,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices) new_device->writeable = 0; new_device->in_fs_metadata = 0; new_device->can_discard = 0; + spin_lock_init(&new_device->io_lock); list_replace_rcu(&device->dev_list, &new_device->dev_list); call_rcu(&device->rcu, free_device); --To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/