From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794049542; b=fJezu0dcqrKTDlLe4VydOm+t66peXLvImoC4z3zM2RvH7PiXlm8tUp7uQkEU7Qpt/+gx A8RH0XaZTT1S7IYWGi6Ym5PZn6RsgJevQ1CSaFubTyK8WJ1ljw5p+9/AH79rny8RAy4MY yqKPi48h4/fBA5XuiI8Jxuz2n4Z8+gr2sjocxSdwvtxq9cbSYO3IxacfV9en4VKZyVMM9 /INdznqA/pmZlRLV7e7Dn0QYslNoQcYIqk6716taEGiF6ZiVTJ7e0u29oql6Tm9jysRyT nUkWwEvKpIg0FCudHn9MERO60oMNfZHFb74SyKVsOG9GTL8Vaa3P4YVV0PTbslCeTWA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049542; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=pPUQA2c4Ww5Fnn7Ow3K+PcW1e5yDNYX9CrEbenbaAa0=; b=uAOX6lnKUIDwuaTgTWlesjiIWK5smbx0tdLPikDHqFwxAyX7kTikQbQyJlUhIm/bQjKi lyCCSfFenA39L36HPs0+DIXkClhpVRgdcy5OtSeiPYegwcz/h907Jm7Vbc7aDOupMMhwR 1mQCqSSHUWVf0mIFyORWz3PnyoUavKZogBxQEr9Zlh1iu6WAKBsZaSjV7bDDvOhA0lmn5 t66HzIxHj9nPs7xufofi0COj+fBMME/saO/2LTJuzyLjyGoAN5YeDwCgewLJftQlL4BpW Ka81x5RWvRzPYLvkoxwrdR7BQ6avzUemXTPflZBTLrEAZvVkzs2i3Jnjx7OyzmVUTFA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gupBQIvE; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A566606A32C for ; Sat, 7 Nov 2026 11:05:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gupBQIvE Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA4F51F0089F; Sat, 7 Nov 2026 11:05:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049542; bh=pPUQA2c4Ww5Fnn7Ow3K+PcW1e5yDNYX9CrEbenbaAa0=; h=From:To:Cc:Subject:Date; b=gupBQIvEx+VZrQzhqz4FHfHhbfYcO5FQaVi/kAa6eG53E5ELjjGFfifTMUdUBuEG2 beWMYO6NCRGlCvIwwrjti6NzrF4IEaLUnHG6yGFJ9BE3avyA0FGxnv24A7L3fp/dUx FLU+Io6ScKCpZ6eL0cmyaZ2139LoTjq84JTk3nOTpuo0kTFTy4NRAK907odC8xXNVh B4gvDBtITxXyJD0R/8pXQE0RKY8tBXmivqCc895jJ6bzm4lTY2Fg4dAqxrwRrsc00d G149sCw4y3KfrG4iR1K6igHZkbX0apB+qBRqLk99f/iwq9BxLxqBmA/DbjscMQsw9D F1oaCAaGqu11g== From: Sasha Levin To: zhaonanzhe@xiaomi.com, sashiko-bot@kernel.org, chao@kernel.org, jaegeuk@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] f2fs: read i_size once in f2fs_vm_page_mkwrite" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:05:40 -0500 Message-ID: <20261107060540-failed-5.15-c04f209773ec@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x c04f209773ecb31e592cababce0d6658ee0b8d58 # git commit -s git send-email --to '' --in-reply-to '20261107060540-failed-5.15-c04f209773ec@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From c04f209773ecb31e592cababce0d6658ee0b8d58 Mon Sep 17 00:00:00 2001 From: Nanzhe Zhao Date: Tue, 13 Oct 2026 18:56:28 +0800 Subject: [PATCH] f2fs: read i_size once in f2fs_vm_page_mkwrite f2fs_vm_page_mkwrite() reads i_size twice: once to check whether the folio is partially beyond EOF, and once to calculate the offset for folio_zero_segment(). But a concurrent buffered write can extend isize and cause the following race condition to corrupt data: buffered write writes [0,3500) CPU0 (write fault) CPU1 (buffered write) ---- ---- f2fs_vm_page_mkwrite() folio_lock(folio) if (((loff_t)(folio->index + 1) << PAGE_SHIFT) > i_size_read(inode)) /* i_size_read() = 3500 */ write(fd, buf, 200, 4096) /* writes into page1, does not wait for folio lock */ i_size_write(inode, 4296) offset = i_size_read(inode) & ~PAGE_MASK /* i_size_read() = 4296, offset = 200 */ folio_zero_segment(folio, offset, folio_size(folio)) /* valid data [200, 3500) is zeroed */ Fix this by reading i_size once and using the same value for both the EOF check and the zeroing offset. Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20261012030315.978375-1-zhaonanzhe%40xiaomi.com Fixes: fbfa2cc58d53 ("f2fs: add file operations") Cc: stable@vger.kernel.org Signed-off-by: Nanzhe Zhao Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/file.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 4363e28056e6b..713fb6f49bcb3 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -125,6 +125,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) struct f2fs_sb_info *sbi = F2FS_I_SB(inode); struct dnode_of_data dn; bool need_alloc = !f2fs_is_pinned_file(inode); + loff_t isize; int err = 0; vm_fault_t ret; @@ -188,8 +189,14 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) filemap_invalidate_lock_shared(inode->i_mapping); folio_lock(folio); + /* + * A concurrent buffered write can extend isize, so we store isize in a + * local variable to let the zeroing offset match the EOF check below. + */ + isize = i_size_read(inode); + if (unlikely(folio->mapping != inode->i_mapping || - folio_pos(folio) > i_size_read(inode) || + folio_pos(folio) > isize || !folio_test_uptodate(folio))) { folio_unlock(folio); err = -EFAULT; @@ -219,11 +226,10 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) f2fs_wait_on_block_writeback(inode, dn.data_blkaddr); /* page is wholly or partially inside EOF */ - if (((loff_t)(folio->index + 1) << PAGE_SHIFT) > - i_size_read(inode)) { + if (((loff_t)(folio->index + 1) << PAGE_SHIFT) > isize) { loff_t offset; - offset = i_size_read(inode) & ~PAGE_MASK; + offset = isize & ~PAGE_MASK; folio_zero_segment(folio, offset, folio_size(folio)); } folio_mark_dirty(folio); -- 2.53.0