From 069442da9721051a1b3154ec92cb23cff21278c0 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 21 Dec 2015 17:05:42 +1100 Subject: [PATCH] common: Add more checks to _check_dmesg 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: [] btrfs_dev_replace_finishing+0x3e/0x696 [btrfs] [ 912.948929] #1: (uuid_mutex){+.+.+.}, at: [] btrfs_dev_replace_finishing+0xf5/0x696 [btrfs] [ 912.950987] #2: (&fs_devs->device_list_mutex){+.+.+.}, at: [] btrfs_dev_replace_finishing+0x10e/0x696 [btrfs] [ 912.953265] #3: (&fs_info->chunk_mutex){+.+...}, at: [] 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: [] __blkdev_get+0xa3/0x3d9 [ 912.990801] [ 912.990801] but task is already holding lock: [ 912.990801] (&fs_info->chunk_mutex){+.+.+.}, at: [] 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 Reviewed-by: Eryu Guan Signed-off-by: Dave Chinner --- common/rc | 2 ++ 1 file changed, 2 insertions(+) diff --git a/common/rc b/common/rc index 4c2f42c8..dd50aa90 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)" -- 2.39.5