The patch titled Subject: tmpfs: change final i_blocks BUG to WARNING has been added to the -mm tree. Its filename is tmpfs-change-final-i_blocks-bug-to-warning.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins <hughd@xxxxxxxxxx> Subject: tmpfs: change final i_blocks BUG to WARNING 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@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/shmem.c~tmpfs-change-final-i_blocks-bug-to-warning mm/shmem.c --- a/mm/shmem.c~tmpfs-change-final-i_blocks-bug-to-warning +++ a/mm/shmem.c @@ -643,7 +643,7 @@ static void shmem_evict_inode(struct ino kfree(info->symlink); simple_xattrs_free(&info->xattrs); - BUG_ON(inode->i_blocks); + WARN_ON(inode->i_blocks); shmem_free_inode(inode->i_sb); clear_inode(inode); } _ Patches currently in -mm which might be from hughd@xxxxxxxxxx are linux-next.patch tmpfs-fix-shmem_getpage_gfp-vm_bug_on.patch tmpfs-change-final-i_blocks-bug-to-warning.patch mm-add-comment-on-storage-key-dirty-bit-semantics.patch mm-refactor-reinsert-of-swap_info-in-sys_swapoff.patch mm-do-not-call-frontswap_init-during-swapoff.patch swap-add-a-simple-detector-for-inappropriate-swapin-readahead.patch swap-add-a-simple-detector-for-inappropriate-swapin-readahead-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html