2022-11-19 05:04:34

by ChenXiaoSong

Subject: [PATCH] cifs: fix missing unlock in cifs_file_copychunk_range()

xfstests generic/013 and generic/476 reported WARNING as follows:

WARNING: lock held when returning to user space!
6.1.0-rc5+ #4 Not tainted
------------------------------------------------
fsstress/504233 is leaving the kernel with locks still held!
2 locks held by fsstress/504233:
#0: ffff888054c38850 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at:
lock_two_nondirectories+0xcf/0xf0
#1: ffff8880b8fec750 (&sb->s_type->i_mutex_key#21/4){+.+.}-{3:3}, at:
lock_two_nondirectories+0xb7/0xf0

This will lead to deadlock and hungtask.

Fix this by releasing locks when failed to write out on a file range in
cifs_file_copychunk_range().

Fixes: 3e3761f1ec7d ("smb3: use filemap_write_and_wait_range instead of filemap_write_and_wait")
Signed-off-by: ChenXiaoSong <[email protected]>
---
fs/cifs/cifsfs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index fe220686bba4..712a43161448 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1281,7 +1281,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
rc = filemap_write_and_wait_range(src_inode->i_mapping, off,
off + len - 1);
if (rc)
- goto out;
+ goto unlock;

/* should we flush first and last page first */
truncate_inode_pages(&target_inode->i_data, 0);
@@ -1297,6 +1297,8 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
* that target is updated on the server
*/
CIFS_I(target_inode)->time = 0;
+
+unlock:
/* although unlocking in the reverse order from locking is not
* strictly necessary here it is a little cleaner to be consistent
*/
--
2.31.1

2022-11-19 20:30:07

by Steve French

Subject: Re: [PATCH] cifs: fix missing unlock in cifs_file_copychunk_range()

good catch.

merged into cifs-2.6.git for-next

On Fri, Nov 18, 2022 at 10:09 PM ChenXiaoSong <[email protected]> wrote:
>
> xfstests generic/013 and generic/476 reported WARNING as follows:
>
> WARNING: lock held when returning to user space!
> 6.1.0-rc5+ #4 Not tainted
> ------------------------------------------------
> fsstress/504233 is leaving the kernel with locks still held!
> 2 locks held by fsstress/504233:
> #0: ffff888054c38850 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at:
> lock_two_nondirectories+0xcf/0xf0
> #1: ffff8880b8fec750 (&sb->s_type->i_mutex_key#21/4){+.+.}-{3:3}, at:
> lock_two_nondirectories+0xb7/0xf0
>
> This will lead to deadlock and hungtask.
>
> Fix this by releasing locks when failed to write out on a file range in
> cifs_file_copychunk_range().
>
> Fixes: 3e3761f1ec7d ("smb3: use filemap_write_and_wait_range instead of filemap_write_and_wait")
> Signed-off-by: ChenXiaoSong <[email protected]>
> ---
> fs/cifs/cifsfs.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index fe220686bba4..712a43161448 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -1281,7 +1281,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
> rc = filemap_write_and_wait_range(src_inode->i_mapping, off,
> off + len - 1);
> if (rc)
> - goto out;
> + goto unlock;
>
> /* should we flush first and last page first */
> truncate_inode_pages(&target_inode->i_data, 0);
> @@ -1297,6 +1297,8 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
> * that target is updated on the server
> */
> CIFS_I(target_inode)->time = 0;
> +
> +unlock:
> /* although unlocking in the reverse order from locking is not
> * strictly necessary here it is a little cleaner to be consistent
> */
> --
> 2.31.1
>


--
Thanks,

Steve

2022-11-21 15:48:14

by Paulo Alcantara

Subject: Re: [PATCH] cifs: fix missing unlock in cifs_file_copychunk_range()

ChenXiaoSong <[email protected]> writes:

> xfstests generic/013 and generic/476 reported WARNING as follows:
>
> WARNING: lock held when returning to user space!
> 6.1.0-rc5+ #4 Not tainted
> ------------------------------------------------
> fsstress/504233 is leaving the kernel with locks still held!
> 2 locks held by fsstress/504233:
> #0: ffff888054c38850 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at:
> lock_two_nondirectories+0xcf/0xf0
> #1: ffff8880b8fec750 (&sb->s_type->i_mutex_key#21/4){+.+.}-{3:3}, at:
> lock_two_nondirectories+0xb7/0xf0
>
> This will lead to deadlock and hungtask.
>
> Fix this by releasing locks when failed to write out on a file range in
> cifs_file_copychunk_range().
>
> Fixes: 3e3761f1ec7d ("smb3: use filemap_write_and_wait_range instead of filemap_write_and_wait")
> Signed-off-by: ChenXiaoSong <[email protected]>
> ---
> fs/cifs/cifsfs.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Paulo Alcantara (SUSE) <[email protected]>