The patch titled fs: fix page_mkwrite error cases in core code and btrfs has been added to the -mm tree. Its filename is fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs.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 *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: fs: fix page_mkwrite error cases in core code and btrfs From: Nick Piggin <npiggin@xxxxxxx> page_mkwrite is called with neither the page lock nor the ptl held. This means a page can be concurrently truncated or invalidated out from underneath it. Callers are supposed to prevent truncate races themselves, however previously the only thing they can do in case they hit one is to raise a SIGBUS. A sigbus is wrong for the case that the page has been invalidated or truncated within i_size (eg. hole punched). Callers may also have to perform memory allocations in this path, where again, SIGBUS would be wrong. The previous patch ("mm: page_mkwrite change prototype to match fault") made it possible to properly specify errors. Convert the generic buffer.c code and btrfs to return sane error values (in the case of page removed from pagecache, VM_FAULT_NOPAGE will cause the fault handler to exit without doing anything, and the fault will be retried properly). This fixes core code, and converts btrfs as a template/example. All other filesystems defining their own page_mkwrite should be fixed in a similar manner. Acked-by: Chris Mason <chris.mason@xxxxxxxxxx> Signed-off-by: Nick Piggin <npiggin@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/btrfs/inode.c | 11 +++++++---- fs/buffer.c | 12 ++++++++---- 2 files changed, 15 insertions(+), 8 deletions(-) diff -puN fs/btrfs/inode.c~fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs fs/btrfs/inode.c --- a/fs/btrfs/inode.c~fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs +++ a/fs/btrfs/inode.c @@ -4307,10 +4307,15 @@ int btrfs_page_mkwrite(struct vm_area_st u64 page_end; ret = btrfs_check_data_free_space(root, inode, PAGE_CACHE_SIZE); - if (ret) + if (ret) { + if (ret == -ENOMEM) + ret = VM_FAULT_OOM; + else /* -ENOSPC, -EIO, etc */ + ret = VM_FAULT_SIGBUS; goto out; + } - ret = -EINVAL; + ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ again: lock_page(page); size = i_size_read(inode); @@ -4363,8 +4368,6 @@ again: out_unlock: unlock_page(page); out: - if (ret) - ret = VM_FAULT_SIGBUS; return ret; } diff -puN fs/buffer.c~fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs fs/buffer.c --- a/fs/buffer.c~fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs +++ a/fs/buffer.c @@ -2466,7 +2466,7 @@ block_page_mkwrite(struct vm_area_struct struct inode *inode = vma->vm_file->f_path.dentry->d_inode; unsigned long end; loff_t size; - int ret = -EINVAL; + int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ lock_page(page); size = i_size_read(inode); @@ -2486,10 +2486,14 @@ block_page_mkwrite(struct vm_area_struct if (!ret) ret = block_commit_write(page, 0, end); -out_unlock: - if (ret) - ret = VM_FAULT_SIGBUS; + if (unlikely(ret)) { + if (ret == -ENOMEM) + ret = VM_FAULT_OOM; + else /* -ENOSPC, -EIO, etc */ + ret = VM_FAULT_SIGBUS; + } +out_unlock: unlock_page(page); return ret; } _ Patches currently in -mm which might be from npiggin@xxxxxxx are fs-new-inode-i_state-corruption-fix.patch linux-next.patch slqb-use-correct-name-for-rcu-callback.patch slqb-cleanup-for-concatenating-kmlist.patch fs-avoid-i_new-inodes.patch vmap-remove-needless-lock-and-list-in-vmap.patch page_fault-retry-with-nopage_retry.patch page_fault-retry-with-nopage_retry-fix.patch radix-tree-gang-set-if-tagged-operation.patch mm-dont-call-mark_page_accessed-in-do_swap_page.patch mm-update_page_reclaim_stat-is-called-from-page-fault-path.patch mm-add-comment-why-mark_page_accessed-would-be-better-than-pte_mkyoung-in-follow_page.patch mm-add-comment-why-mark_page_accessed-would-be-better-than-pte_mkyoung-in-follow_page-fix.patch mm-page_mkwrite-change-prototype-to-match-fault.patch fs-fix-page_mkwrite-error-cases-in-core-code-and-btrfs.patch reiser4.patch fs-symlink-write_begin-allocation-context-fix-reiser4-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