FAILED: patch "[PATCH] f2fs: fix to avoid mapping wrong physical block for swapfile" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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 <[email protected]>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 5c145c03188bc9ba1c29e0bc4d527a5978fc47f9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026021700-wrongness-undermine-54e0@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5c145c03188bc9ba1c29e0bc4d527a5978fc47f9 Mon Sep 17 00:00:00 2001
From: Chao Yu <[email protected]>
Date: Tue, 13 Jan 2026 14:22:29 +0800
Subject: [PATCH] f2fs: fix to avoid mapping wrong physical block for swapfile

Xiaolong Guo reported a f2fs bug in bugzilla [1]

[1] https://bugzilla.kernel.org/show_bug.cgi?id=220951

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 boundaries, the function incorrectly treats it as the last extent, failing to map subsequent extents. This results in incorrect swap_extent creation where only the first extent is mapped, causing subsequent swap writes to overwrite wrong 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=11002, file offset=0, start blkaddr=0x43143, len=0x1
(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=28011, file offset=0, start blkaddr=0x13cd4, len=0x1
stress-ng-swap-5966: f2fs_map_blocks: ino=28011, file offset=1, start blkaddr=0x60c84b, len=0xff

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 = false;

    not_aligned++;

    nr_pblocks = roundup(nr_pblocks, blks_per_sec);
    if (cur_lblock + nr_pblocks > sis->max)
        nr_pblocks -= blks_per_sec;

    /* this extent is last one */
    if (!nr_pblocks) {
        nr_pblocks = last_lblock - cur_lblock;
        last_extent = true;
    }

    ret = f2fs_migrate_blocks(inode, cur_lblock, nr_pblocks);
    if (ret) {
        if (ret == -ENOENT)
            ret = -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 = 0. The code then incorrectly assumes this is the last extent, sets nr_pblocks = last_lblock - cur_lblock (entire swapfile), and performs migration. After migration, it doesn't retry mapping, so subsequent extents are never processed. "

In order to fix this issue, we need to lookup block mapping info after we migrate all blocks in the tail of swapfile.

index 3c2af0ef62bb..4e2f10bd2b07 100644
@@ -4206,6 +4206,7 @@ static int check_swap_activate(struct swap_info_struct *sis,
 
 	while (cur_lblock < last_lblock && cur_lblock < sis->max) {
 		struct f2fs_map_blocks map;
+		bool last_extent = false;
 retry:
 		cond_resched();
 

@@ -4231,11 +4232,10 @@ static int check_swap_activate(struct swap_info_struct *sis,
 		pblock = map.m_pblk;
 		nr_pblocks = map.m_len;
 
-		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 = 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++;
 
 			nr_pblocks = roundup(nr_pblocks, blks_per_sec);

@@ -4256,8 +4256,8 @@ static int check_swap_activate(struct swap_info_struct *sis,
 				goto out;
 			}
 
-			if (!last_extent)
-				goto retry;
+			/* lookup block mapping info after block migration */
+			goto retry;
 		}
 
 		if (cur_lblock + nr_pblocks >= sis->max)

From: Wenjie Qi <[email protected]>

[ Upstream commit 0f9b12142be1af8555cfe53c6fbecb8e60a40dac ]

If the max open zones of zoned devices are less than the active logs of F2FS, the device may error due to insufficient zone resources when multiple active logs are being written at the same time.

Stable-dep-of: 5c145c03188b ("f2fs: fix to avoid mapping wrong physical block for swapfile")

---
 fs/f2fs/f2fs.h  |  1 +
 fs/f2fs/super.c | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

index 9a4eabd11c734..d7afa8bc0ff8e 100644
@@ -1567,6 +1567,7 @@ struct f2fs_sb_info {
 
 #ifdef CONFIG_BLK_DEV_ZONED
 	unsigned int blocks_per_blkz;		/* F2FS blocks per zone */
+	unsigned int max_open_zones;		/* max open zone resources of the zoned device */
 #endif
 
 	/* for node-related operations */

index dd6cd014fefb0..9bd71d68cd95c 100644
@@ -2359,6 +2359,17 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	if (err)
 		goto restore_opts;
 
+#ifdef CONFIG_BLK_DEV_ZONED
+	if (f2fs_sb_has_blkzoned(sbi) &&
+		sbi->max_open_zones < F2FS_OPTION(sbi).active_logs) {
+		f2fs_err(sbi,
+			"zoned: max open zones %u is too small, need at least %u open zones",
+				 sbi->max_open_zones, F2FS_OPTION(sbi).active_logs);
+		err = -EINVAL;
+		goto restore_opts;
+	}
+#endif
+
 	/* flush outstanding errors before changing fs state */
 	flush_work(&sbi->s_error_work);
 

@@ -3902,11 +3913,24 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
 	sector_t nr_sectors = bdev_nr_sectors(bdev);
 	struct f2fs_report_zones_args rep_zone_arg;
 	u64 zone_sectors;
+	unsigned int max_open_zones;
 	int ret;
 
 	if (!f2fs_sb_has_blkzoned(sbi))
 		return 0;
 
+	if (bdev_is_zoned(FDEV(devi).bdev)) {
+		max_open_zones = bdev_max_open_zones(bdev);
+		if (max_open_zones && (max_open_zones < sbi->max_open_zones))
+			sbi->max_open_zones = max_open_zones;
+		if (sbi->max_open_zones < F2FS_OPTION(sbi).active_logs) {
+			f2fs_err(sbi,
+				"zoned: max open zones %u is too small, need at least %u open zones",
+				sbi->max_open_zones, F2FS_OPTION(sbi).active_logs);
+			return -EINVAL;
+		}
+	}
+
 	zone_sectors = bdev_zone_sectors(bdev);
 	if (sbi->blocks_per_blkz && sbi->blocks_per_blkz !=
 				SECTOR_TO_BLOCK(zone_sectors))

@@ -4188,6 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 
 	logical_blksize = bdev_logical_block_size(sbi->sb->s_bdev);
 	sbi->aligned_blksize = true;
+#ifdef CONFIG_BLK_DEV_ZONED
+	sbi->max_open_zones = UINT_MAX;
+#endif
 
 	for (i = 0; i < max_devices; i++) {
 		if (i == 0)

2.51.0

From: Chao Yu <[email protected]>

[ Upstream commit 5c145c03188bc9ba1c29e0bc4d527a5978fc47f9 ]

Xiaolong Guo reported a f2fs bug in bugzilla [1]

[1] https://bugzilla.kernel.org/show_bug.cgi?id=220951

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 boundaries, the function incorrectly treats it as the last extent, failing to map subsequent extents. This results in incorrect swap_extent creation where only the first extent is mapped, causing subsequent swap writes to overwrite wrong 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=11002, file offset=0, start blkaddr=0x43143, len=0x1
(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=28011, file offset=0, start blkaddr=0x13cd4, len=0x1
stress-ng-swap-5966: f2fs_map_blocks: ino=28011, file offset=1, start blkaddr=0x60c84b, len=0xff

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 = false;

    not_aligned++;

    nr_pblocks = roundup(nr_pblocks, blks_per_sec);
    if (cur_lblock + nr_pblocks > sis->max)
        nr_pblocks -= blks_per_sec;

    /* this extent is last one */
    if (!nr_pblocks) {
        nr_pblocks = last_lblock - cur_lblock;
        last_extent = true;
    }

    ret = f2fs_migrate_blocks(inode, cur_lblock, nr_pblocks);
    if (ret) {
        if (ret == -ENOENT)
            ret = -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 = 0. The code then incorrectly assumes this is the last extent, sets nr_pblocks = last_lblock - cur_lblock (entire swapfile), and performs migration. After migration, it doesn't retry mapping, so subsequent extents are never processed. "

In order to fix this issue, we need to lookup block mapping info after we migrate all blocks in the tail of swapfile.

---
 fs/f2fs/data.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

index c863e27fd846b..244f2b5a36222 100644
@@ -3934,6 +3934,7 @@ static int check_swap_activate(struct swap_info_struct *sis,
 
 	while (cur_lblock < last_lblock && cur_lblock < sis->max) {
 		struct f2fs_map_blocks map;
+		bool last_extent = false;
 retry:
 		cond_resched();
 

@@ -3959,11 +3960,10 @@ static int check_swap_activate(struct swap_info_struct *sis,
 		pblock = map.m_pblk;
 		nr_pblocks = map.m_len;
 
-		if ((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec ||
-				nr_pblocks % blks_per_sec ||
-				!f2fs_valid_pinned_area(sbi, pblock)) {
-			bool last_extent = false;
-
+		if (!last_extent &&
+			((pblock - SM_I(sbi)->main_blkaddr) % blks_per_sec ||
+			nr_pblocks % blks_per_sec ||
+			!f2fs_valid_pinned_area(sbi, pblock))) {
 			not_aligned++;
 
 			nr_pblocks = roundup(nr_pblocks, blks_per_sec);

@@ -3984,8 +3984,8 @@ static int check_swap_activate(struct swap_info_struct *sis,
 				goto out;
 			}
 
-			if (!last_extent)
-				goto retry;
+			/* lookup block mapping info after block migration */
+			goto retry;
 		}
 
 		if (cur_lblock + nr_pblocks >= sis->max)

2.51.0