From nobody Sat Feb 7 15:09:51 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B975134F48A for ; Tue, 13 Jan 2026 06:22:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768285356; cv=none; b=Gm1Sf2bkAZxa+WBnCnN8lFfxYsVR7sCWj4TnJL/2OOXUW8o6TvPDVpbMnzcALoRhgRydBbIToOHABpz+Pnlsw1itxRG+Etz0YTiNGQHgfBddHp9YqGT1Nd6YwNo93S8P4kwYS/7IP+e+aPCygUktXErKDOM0PPQ+YN6kTJQTtvA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768285356; c=relaxed/simple; bh=zRr7rMbJ2ARx4Z/TuMxKy5Qs8jYhMbcVBO5jFgP3AcA=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=kIQG4iQIXx2kubFm2FrZt2e9WsWchHdQjbSVPNyz6IsUzKzI6Y/GcSUAil03JqmWMZLZRLqC3pkA9ZSAKTsfz6c60E2MX7lcqXaZGFor8q17tMskJMRfYU42wIwkswvHzlPC7RqlKVdyEgGMx6/mvP7T68BbzgsnqbrJHD/SuUc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=C47KMuhZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="C47KMuhZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E7C6C116C6; Tue, 13 Jan 2026 06:22:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768285356; bh=zRr7rMbJ2ARx4Z/TuMxKy5Qs8jYhMbcVBO5jFgP3AcA=; h=From:To:Cc:Subject:Date:From; b=C47KMuhZBHHN3evJwIdrdhqdmaxnguI54p9oCpUjIuo1IiIZPu8musvF96NTZhNgP hGKFiJ5VndeeVlfrI0HMK7inno7ehnnWzliztLg4WBE1JzuOtnDm/Oz+fze2q9XG/L 2W5W7lRMLvKVPtS2g86+BmrxpioJC/KKiEqrjf84Lsdm3XeQh8IgFB+m+Qav2Z/INz HA1YPHNQPeKuEu4Tb7vIUq6d7ws6bdVheJ8UF+OIAQqduVlfW4hrFk5aN9jjxpzu9x ZhttcQxGtS02DnGjMcXeIPfguaTQxV6s6PYYNgi/PydryVafEU6O06FespJ+AOeBC/ 0zR+QoeUKYAdg== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu , stable@kernel.org, Daeho Jeong , Xiaolong Guo Subject: [PATCH] f2fs: fix to avoid mapping wrong physical block for swapfile Date: Tue, 13 Jan 2026 14:22:29 +0800 Message-Id: <20260113062229.4062-1-chao@kernel.org> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Xiaolong Guo reported a f2fs bug in bugzilla [1] [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D220951 Quoted: "When using stress-ng's swap stress test on F2FS filesystem with kernel 6.6= +, the system experiences data corruption leading to either: 1 dm-verity corruption errors and device reboot 2 F2FS node corruption errors and boot hangs The issue occurs specifically when: 1 Using F2FS filesystem (ext4 is unaffected) 2 Swapfile size is less than F2FS section size (2MB) 3 Swapfile has fragmented physical layout (multiple non-contiguous extents) 4 Kernel version is 6.6+ (6.1 is unaffected) The root cause is in check_swap_activate() function in fs/f2fs/data.c. When= the first extent of a small swapfile (< 2MB) is not aligned to section boundari= es, the function incorrectly treats it as the last extent, failing to map subsequent extents. This results in incorrect swap_extent creation where on= ly the first extent is mapped, causing subsequent swap writes to overwrite wro= ng physical locations (other files' data). Steps to Reproduce 1 Setup a device with F2FS-formatted userdata partition 2 Compile stress-ng from https://github.com/ColinIanKing/stress-ng 3 Run swap stress test: (Android devices) adb shell "cd /data/stressng; ./stress-ng-64 --metrics-brief --timeout 60 --swap 0" Log: 1 Ftrace shows in kernel 6.6, only first extent is mapped during second f2fs_map_blocks call in check_swap_activate(): stress-ng-swap-8990: f2fs_map_blocks: ino=3D11002, file offset=3D0, start blkaddr=3D0x43143, len=3D0x1 (Only 4KB mapped, not the full swapfile) 2 in kernel 6.1, both extents are correctly mapped: stress-ng-swap-5966: f2fs_map_blocks: ino=3D28011, file offset=3D0, start blkaddr=3D0x13cd4, len=3D0x1 stress-ng-swap-5966: f2fs_map_blocks: ino=3D28011, file offset=3D1, start blkaddr=3D0x60c84b, len=3D0xff The problematic code is in check_swap_activate(): if ((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec || nr_pblocks % blks_per_sec || !f2fs_valid_pinned_area(sbi, pblock)) { bool last_extent =3D false; not_aligned++; nr_pblocks =3D roundup(nr_pblocks, blks_per_sec); if (cur_lblock + nr_pblocks > sis->max) nr_pblocks -=3D blks_per_sec; /* this extent is last one */ if (!nr_pblocks) { nr_pblocks =3D last_lblock - cur_lblock; last_extent =3D true; } ret =3D f2fs_migrate_blocks(inode, cur_lblock, nr_pblocks); if (ret) { if (ret =3D=3D -ENOENT) ret =3D -EINVAL; goto out; } if (!last_extent) goto retry; } When the first extent is unaligned and roundup(nr_pblocks, blks_per_sec) exceeds sis->max, we subtract blks_per_sec resulting in nr_pblocks =3D 0. T= he code then incorrectly assumes this is the last extent, sets nr_pblocks =3D last_lblock - cur_lblock (entire swapfile), and performs migration. After migration, it doesn't retry mapping, so subsequent extents are never proces= sed. " In order to fix this issue, we need to lookup block mapping info after we migrate all blocks in the tail of swapfile. Cc: stable@kernel.org Fixes: 9703d69d9d15 ("f2fs: support file pinning for zoned devices") Cc: Daeho Jeong Reported-and-tested-by: Xiaolong Guo Closes: https://bugzilla.kernel.org/show_bug.cgi?id=3D220951 Signed-off-by: Chao Yu --- fs/f2fs/data.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index eea6311998c1..ed5e28352a92 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -4196,6 +4196,7 @@ static int check_swap_activate(struct swap_info_struc= t *sis, =20 while (cur_lblock < last_lblock && cur_lblock < sis->max) { struct f2fs_map_blocks map; + bool last_extent =3D false; retry: cond_resched(); =20 @@ -4221,11 +4222,10 @@ static int check_swap_activate(struct swap_info_str= uct *sis, pblock =3D map.m_pblk; nr_pblocks =3D map.m_len; =20 - if ((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec || - nr_pblocks % blks_per_sec || - f2fs_is_sequential_zone_area(sbi, pblock)) { - bool last_extent =3D false; - + if (!last_extent && + ((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec || + nr_pblocks % blks_per_sec || + f2fs_is_sequential_zone_area(sbi, pblock))) { not_aligned++; =20 nr_pblocks =3D roundup(nr_pblocks, blks_per_sec); @@ -4246,8 +4246,8 @@ static int check_swap_activate(struct swap_info_struc= t *sis, goto out; } =20 - if (!last_extent) - goto retry; + /* lookup block mapping info after block migration */ + goto retry; } =20 if (cur_lblock + nr_pblocks >=3D sis->max) --=20 2.40.1