WARNING in ext4_update_dx_flag

Status: upstream: reported C repro on 2025/10/11 04:39
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+ee9c1340f1991b5b827f@syzkaller.appspotmail.com
First crash: 288d, last: 219d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/10/11 upstream (ToT) 0739473694c4 C [report] WARNING in ext4_update_dx_flag
2026/06/13 upstream (ToT) 2b07ea76fd28 C Failed due to an error; will retry later
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/01/21 13:18 0m bisect fix linux-6.1.y error job log
2025/12/19 13:48 1h31m bisect fix linux-6.1.y OK (0) job log log
2025/11/15 17:52 2h11m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
EXT4-fs (loop0): This should not happen!! Data will be lost
EXT4-fs warning (device loop0): ext4_dirblock_csum_set:427: inode #2: comm syz.0.17: No space for directory leaf checksum. Please run e2fsck -D.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4510 at fs/ext4/ext4.h:2827 ext4_update_dx_flag+0x14c/0x1b0 fs/ext4/ext4.h:2827
Modules linked in:
CPU: 0 PID: 4510 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : ext4_update_dx_flag+0x14c/0x1b0 fs/ext4/ext4.h:2827
lr : ext4_update_dx_flag+0x14c/0x1b0 fs/ext4/ext4.h:2827
sp : ffff800020f276a0
x29: ffff800020f276b0 x28: ffff7000041e4ee0 x27: ffff0000e96a2138
x26: dfff800000000000 x25: 000000002160ec00 x24: ffff0000e96a2130
x23: 0000000000000001 x22: 000000000008d200 x21: dfff800000000000
x20: 00000000ffeffffe x19: ffff0000e96a1e68 x18: 0000000000000000
x17: ffff8000181f8000 x16: ffff8000082d22e0 x15: ffff800017cd8fc0
x14: ffff0000cd5d8a98 x13: 000000002160ec00 x12: 0000000000ff0100
x11: ff00800008dc2284 x10: 0000000000000000 x9 : ffff800008dc2284
x8 : ffff0000cd5d8000 x7 : 000000002160ec00 x6 : 000000000000002a
x5 : ffff0000e96a2150 x4 : ffff0000e96a2140 x3 : ffff800008dc82c8
x2 : 0000000000000010 x1 : 0000000000000400 x0 : 0000000000000000
Call trace:
 ext4_update_dx_flag+0x14c/0x1b0 fs/ext4/ext4.h:2827
 ext4_rename fs/ext4/namei.c:4010 [inline]
 ext4_rename2+0x1954/0x24a0 fs/ext4/namei.c:4258
 vfs_rename+0x954/0xdcc fs/namei.c:4874
 do_renameat2+0x738/0xa54 fs/namei.c:5027
 __do_sys_renameat2 fs/namei.c:5060 [inline]
 __se_sys_renameat2 fs/namei.c:5057 [inline]
 __arm64_sys_renameat2+0xe0/0xfc fs/namei.c:5057
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 12130
hardirqs last  enabled at (12129): [<ffff8000083bf2e4>] seqcount_lockdep_reader_access include/linux/seqlock.h:104 [inline]
hardirqs last  enabled at (12129): [<ffff8000083bf2e4>] ktime_get_coarse_real_ts64+0x114/0x244 kernel/time/timekeeping.c:2261
hardirqs last disabled at (12130): [<ffff80001195a4d8>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (11984): [<ffff80000803092c>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (11982): [<ffff8000080308f8>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/11 06:29 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext4_update_dx_flag
2025/10/11 05:52 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext4_update_dx_flag
2025/10/11 05:16 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 WARNING in ext4_update_dx_flag
2025/10/11 04:38 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in ext4_update_dx_flag
* Struck through repros no longer work on HEAD.