On Wed, Nov 18, 2015 at 04:10:03PM +0000, fdmanana@xxxxxxxxxx wrote:
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> Teach _check_dmesg to look for improper RCU usage and circular locking
> dependency messages. It's useful to check for these as they might point
> to a real problem in the filesystem's implementation (or the current
> implementation just confuses the checker, probably worth simplifying
> the filesystem's implementation).
>
> Currently the test btrfs/071 for example triggers such warnings:
>
> [ 912.924839] ===============================
> [ 912.925617] [ INFO: suspicious RCU usage. ]
> [ 912.926394] 4.3.0-rc5-btrfs-next-17+ #1 Not tainted
> [ 912.927274] -------------------------------
> [ 912.928364] fs/btrfs/volumes.c:1977 suspicious rcu_dereference_check() usage!
> [ 912.929626]
> [ 912.929626] other info that might help us debug this:
> [ 912.929626]
> [ 912.931197]
> [ 912.931197] rcu_scheduler_active = 1, debug_locks = 1
> [ 912.933822] 4 locks held by btrfs/6400:
> [ 912.934558] #0: (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+...}, at: [<ffffffffa046a193>] btrfs_dev_replace_finishing+0x3e/0x696 [btrfs]
> [ 912.948929] #1: (uuid_mutex){+.+.+.}, at: [<ffffffffa046a24a>] btrfs_dev_replace_finishing+0xf5/0x696 [btrfs]
> [ 912.950987] #2: (&fs_devs->device_list_mutex){+.+.+.}, at: [<ffffffffa046a263>] btrfs_dev_replace_finishing+0x10e/0x696 [btrfs]
> [ 912.953265] #3: (&fs_info->chunk_mutex){+.+...}, at: [<ffffffffa046a278>] btrfs_dev_replace_finishing+0x123/0x696 [btrfs]
> (...)
>
> [ 912.987973] ======================================================
> [ 912.989242] [ INFO: possible circular locking dependency detected ]
> [ 912.990583] 4.3.0-rc5-btrfs-next-17+ #1 Not tainted
> [ 912.990801] -------------------------------------------------------
> [ 912.990801] btrfs/6400 is trying to acquire lock:
> [ 912.990801] (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8119d202>] __blkdev_get+0xa3/0x3d9
> [ 912.990801]
> [ 912.990801] but task is already holding lock:
> [ 912.990801] (&fs_info->chunk_mutex){+.+.+.}, at: [<ffffffffa046a278>] btrfs_dev_replace_finishing+0x123/0x696 [btrfs]
> [ 912.990801]
> [ 912.990801] which lock already depends on the new lock.
> [ 912.990801]
> [ 912.990801]
> [ 912.990801] the existing dependency chain (in reverse order) is:
> (...)
>
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Makes sense to me.
Reviewed-by: Eryu Guan <eguan@xxxxxxxxxx>
> ---
> common/rc | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/common/rc b/common/rc
> index 4c2f42c..dd50aa9 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -3055,6 +3055,8 @@ _check_dmesg()
> -e "Oops:" \
> -e "possible recursive locking detected" \
> -e "Internal error" \
> + -e "INFO: suspicious RCU usage" \
> + -e "INFO: possible circular locking dependency detected" \
> $seqres.dmesg
> if [ $? -eq 0 ]; then
> echo "_check_dmesg: something found in dmesg (see $seqres.dmesg)"
> --
> 2.1.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe fstests" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe fstests" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
