On Saturday 10 October 2020 11:04:27 PM IST Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Use XFS_ILOCK_RT{BITMAP,SUM} to annotate grabbing the rt bitmap and
> summary locks when we grow the realtime volume, just like we do most
> everywhere else. This shuts up lockdep warnings about grabbing the
> ILOCK class of locks recursively:
>
> ============================================
> WARNING: possible recursive locking detected
> 5.9.0-rc4-djw #rc4 Tainted: G O
> --------------------------------------------
> xfs_growfs/4841 is trying to acquire lock:
> ffff888035acc230 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_ilock+0xac/0x1a0 [xfs]
>
> but task is already holding lock:
> ffff888035acedb0 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_ilock+0xac/0x1a0 [xfs]
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&xfs_nondir_ilock_class);
> lock(&xfs_nondir_ilock_class);
>
> *** DEADLOCK ***
>
> May be due to missing lock nesting notation
>
The changes in the patch are correct since it uses different lockdep
subclasses for rt bitmap and rt summary inodes.
Reviewed-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_rtalloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index f9119ba3e9d0..ede1baf31413 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -1024,7 +1024,7 @@ xfs_growfs_rt(
> /*
> * Lock out other callers by grabbing the bitmap inode lock.
> */
> - xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);
> + xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP);
> xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
> /*
> * Update the bitmap inode's size ondisk and incore. We need
> @@ -1038,7 +1038,7 @@ xfs_growfs_rt(
> /*
> * Get the summary inode into the transaction.
> */
> - xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL);
> + xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
> xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
> /*
> * Update the summary inode's size. We need to update the
>
>
--
chandan
