Patch 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
added a new btrfs_info call with a couple of btrfs_dev_name() args. This
is wrong since the latter require being called in rcu read side
critical section. Fix it by instead calling btrfs_info_in_rcu. This
fixes the following splat:
=============================
WARNING: suspicious RCU usage
4.16.0-rc2-nbor #463 Not tainted
-----------------------------
fs/btrfs/dev-replace.c:318 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by btrfs/5698:
#0: (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+.}, at: [<00000000942cb4ee>] btrfs_dev_replace_cancel+0xac/0x3f0
stack backtrace:
CPU: 2 PID: 5698 Comm: btrfs Not tainted 4.16.0-rc2-nbor #463
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0x85/0xc9
lockdep_rcu_suspicious+0x123/0x170
btrfs_dev_name.part.1+0x6d/0x80
btrfs_dev_replace_cancel+0x330/0x3f0
btrfs_ioctl+0x2751/0x65b0
? debug_check_no_locks_freed+0x290/0x290
? trace_hardirqs_on_caller+0x400/0x570
? trace_hardirqs_on+0xd/0x10
? btrfs_ioctl_get_supported_features+0x30/0x30
? __handle_mm_fault+0x1aca/0x3230
? lock_downgrade+0x650/0x650
? trace_hardirqs_on+0xd/0x10
? mem_cgroup_commit_charge+0xc0/0xdd0
? _raw_spin_unlock+0x27/0x40
? __handle_mm_fault+0x1aca/0x3230
? lock_downgrade+0x650/0x650
? vm_insert_page+0x650/0x650
? __vma_link_rb+0x125/0x1d0
do_vfs_ioctl+0x184/0xf00
? do_vfs_ioctl+0x184/0xf00
? lock_downgrade+0x650/0x650
? ioctl_preallocate+0x1a0/0x1a0
? up_read+0x1f/0x40
? __do_page_fault+0x5c6/0xb30
? SyS_brk+0x412/0x5f0
? mm_fault_error+0x2e0/0x2e0
SyS_ioctl+0x41/0x70
? do_vfs_ioctl+0xf00/0xf00
do_syscall_64+0x19d/0x5d0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Fixes: 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
---
fs/btrfs/dev-replace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 3b0760f7ec8a..0e776eb90ad8 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -744,7 +744,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
ret = btrfs_commit_transaction(trans);
WARN_ON(ret);
- btrfs_info(fs_info, "dev_replace from %s (devid %llu) to %s canceled",
+ btrfs_info_in_rcu(fs_info, "dev_replace from %s (devid %llu) to %s cancelled",
btrfs_dev_name(src_device), src_device->devid,
btrfs_dev_name(tgt_device));
--
2.7.4
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