| From foo@baz Mon Apr 9 17:09:24 CEST 2018 |
| From: Rabin Vincent <rabinv@axis.com> |
| Date: Wed, 3 May 2017 17:17:21 +0200 |
| Subject: CIFS: silence lockdep splat in cifs_relock_file() |
| |
| From: Rabin Vincent <rabinv@axis.com> |
| |
| |
| [ Upstream commit 560d388950ceda5e7c7cdef7f3d9a8ff297bbf9d ] |
| |
| cifs_relock_file() can perform a down_write() on the inode's lock_sem even |
| though it was already performed in cifs_strict_readv(). Lockdep complains |
| about this. AFAICS, there is no problem here, and lockdep just needs to be |
| told that this nesting is OK. |
| |
| ============================================= |
| [ INFO: possible recursive locking detected ] |
| 4.11.0+ #20 Not tainted |
| --------------------------------------------- |
| cat/701 is trying to acquire lock: |
| (&cifsi->lock_sem){++++.+}, at: cifs_reopen_file+0x7a7/0xc00 |
| |
| but task is already holding lock: |
| (&cifsi->lock_sem){++++.+}, at: cifs_strict_readv+0x177/0x310 |
| |
| other info that might help us debug this: |
| Possible unsafe locking scenario: |
| |
| CPU0 |
| ---- |
| lock(&cifsi->lock_sem); |
| lock(&cifsi->lock_sem); |
| |
| *** DEADLOCK *** |
| |
| May be due to missing lock nesting notation |
| |
| 1 lock held by cat/701: |
| #0: (&cifsi->lock_sem){++++.+}, at: cifs_strict_readv+0x177/0x310 |
| |
| stack backtrace: |
| CPU: 0 PID: 701 Comm: cat Not tainted 4.11.0+ #20 |
| Call Trace: |
| dump_stack+0x85/0xc2 |
| __lock_acquire+0x17dd/0x2260 |
| ? trace_hardirqs_on_thunk+0x1a/0x1c |
| ? preempt_schedule_irq+0x6b/0x80 |
| lock_acquire+0xcc/0x260 |
| ? lock_acquire+0xcc/0x260 |
| ? cifs_reopen_file+0x7a7/0xc00 |
| down_read+0x2d/0x70 |
| ? cifs_reopen_file+0x7a7/0xc00 |
| cifs_reopen_file+0x7a7/0xc00 |
| ? printk+0x43/0x4b |
| cifs_readpage_worker+0x327/0x8a0 |
| cifs_readpage+0x8c/0x2a0 |
| generic_file_read_iter+0x692/0xd00 |
| cifs_strict_readv+0x29f/0x310 |
| generic_file_splice_read+0x11c/0x1c0 |
| do_splice_to+0xa5/0xc0 |
| splice_direct_to_actor+0xfa/0x350 |
| ? generic_pipe_buf_nosteal+0x10/0x10 |
| do_splice_direct+0xb5/0xe0 |
| do_sendfile+0x278/0x3a0 |
| SyS_sendfile64+0xc4/0xe0 |
| entry_SYSCALL_64_fastpath+0x1f/0xbe |
| |
| Signed-off-by: Rabin Vincent <rabinv@axis.com> |
| Acked-by: Pavel Shilovsky <pshilov@microsoft.com> |
| Signed-off-by: Steve French <smfrench@gmail.com> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/cifs/file.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/fs/cifs/file.c |
| +++ b/fs/cifs/file.c |
| @@ -589,7 +589,7 @@ cifs_relock_file(struct cifsFileInfo *cf |
| struct cifs_tcon *tcon = tlink_tcon(cfile->tlink); |
| int rc = 0; |
| |
| - down_read(&cinode->lock_sem); |
| + down_read_nested(&cinode->lock_sem, SINGLE_DEPTH_NESTING); |
| if (cinode->can_cache_brlcks) { |
| /* can cache locks - no need to relock */ |
| up_read(&cinode->lock_sem); |