diff options
| author | Hugh Dickins <hughd@google.com> | 2012-11-16 14:15:04 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-11-26 11:37:47 -0800 |
| commit | ec5924204b7fa09a679c4456ac8e2176a2950ce6 (patch) | |
| tree | b2e8878d42c734b9004f5d5ced95e4160abcede1 /mm | |
| parent | f86c309e326f800e8fb028df35051aac5a26ef8d (diff) | |
tmpfs: change final i_blocks BUG to WARNING
commit 0f3c42f522dc1ad7e27affc0a4aa8c790bce0a66 upstream.
Under a particular load on one machine, I have hit shmem_evict_inode()'s
BUG_ON(inode->i_blocks), enough times to narrow it down to a particular
race between swapout and eviction.
It comes from the "if (freed > 0)" asymmetry in shmem_recalc_inode(),
and the lack of coherent locking between mapping's nrpages and shmem's
swapped count. There's a window in shmem_writepage(), between lowering
nrpages in shmem_delete_from_page_cache() and then raising swapped
count, when the freed count appears to be +1 when it should be 0, and
then the asymmetry stops it from being corrected with -1 before hitting
the BUG.
One answer is coherent locking: using tree_lock throughout, without
info->lock; reasonable, but the raw_spin_lock in percpu_counter_add() on
used_blocks makes that messier than expected. Another answer may be a
further effort to eliminate the weird shmem_recalc_inode() altogether,
but previous attempts at that failed.
So far undecided, but for now change the BUG_ON to WARN_ON: in usual
circumstances it remains a useful consistency check.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/shmem.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 40383cddc916..a859b06d573f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -595,7 +595,7 @@ static void shmem_evict_inode(struct inode *inode) kfree(xattr->name); kfree(xattr); } - BUG_ON(inode->i_blocks); + WARN_ON(inode->i_blocks); shmem_free_inode(inode->i_sb); end_writeback(inode); } |