WARNING in ext4_write_inode (4)

Status: upstream: reported on 2026/09/22 19:16
Subsystems: ext4
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+77d4c409352d8b3a015e@syzkaller.appspotmail.com
First crash: 49d, last: 44d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
9bb47692 repro-c Reproduced: ✅ ❓ WARNING in ext4_write_inode (4) 2026/10/19 19:50 2026/10/19 19:50 2026/10/19 22:02 e931f328
a629126c assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING in ext4_write_inode (4) 2026/09/20 02:29 2026/09/20 02:29 2026/09/20 03:07 853b104b
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] WARNING in ext4_write_inode (4) 0 (1) 2026/09/22 19:16
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 WARNING in ext4_write_inode -1 6 2448d 2449d 0/1 auto-closed as invalid on 2020/06/22 22:10
upstream WARNING in ext4_write_inode ext4 -1 13 2438d 2445d 15/29 fixed on 2020/05/10 10:41
upstream WARNING in ext4_write_inode (2) ext4 -1 syz, C 130 750d 1729d 0/29 auto-obsoleted due to no activity on 2025/01/25 16:58
linux-5.15 WARNING in ext4_write_inode -1 1 1319d 1319d 0/3 auto-obsoleted due to no activity on 2023/07/26 10:16
linux-4.19 WARNING in ext4_write_inode -1 1 2448d 2448d 0/1 auto-closed as invalid on 2020/06/22 14:27
upstream WARNING in ext4_write_inode (3) prio:high ext4 -1 10 155d 386d 0/29 auto-obsoleted due to no activity on 2026/09/12 13:20
linux-6.1 WARNING in ext4_write_inode -1 5 1242d 1323d 0/3 auto-obsoleted due to no activity on 2023/09/21 16:26
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/10/19 22:03 16m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c03c1a14507dfaf8b856c2608f9ac216021fc222 no crash job log log

Sample crash report:
------------[ cut here ]------------
current->flags & PF_MEMALLOC
WARNING: fs/ext4/inode.c:5879 at ext4_write_inode+0x2af/0x350 fs/ext4/inode.c:5879, CPU#0: kswapd0/71
Modules linked in:
CPU: 0 UID: 0 PID: 71 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ext4_write_inode+0x2af/0x350 fs/ext4/inode.c:5879
Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 13 9d 34 ff e8 ae 6e 9f fe bd fb ff ff ff eb d9 e8 02 9d 34 ff 90 <0f> 0b 90 eb ce e8 f7 9c 34 ff bd fb ff ff ff eb c2 e8 eb 9c 34 ff
RSP: 0018:ffffc90000cf6ef0 EFLAGS: 00010293
RAX: ffffffff8293500e RBX: dffffc0000000000 RCX: ffff88801d340000
RDX: 0000000000000000 RSI: 0000000000000800 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff907a767f R09: 1ffffffff20f4ecf
R10: dffffc0000000000 R11: ffffffff82934d60 R12: ffff88801d34002c
R13: ffff88801305f810 R14: 0000000000000800 R15: ffff88801d340000
FS:  0000000000000000(0000) GS:ffff88808c2c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3c165c4120 CR3: 0000000043a14000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 write_inode fs/fs-writeback.c:1608 [inline]
 __writeback_single_inode+0x69d/0x1220 fs/fs-writeback.c:1851
 writeback_single_inode+0x544/0xf70 fs/fs-writeback.c:1926
 write_inode_now+0x1c2/0x290 fs/fs-writeback.c:3080
 iput_final fs/inode.c:2005 [inline]
 iput+0x98b/0xf00 fs/inode.c:2064
 dentry_kill+0x1b9/0x880 fs/dcache.c:826
 shrink_kill fs/dcache.c:1275 [inline]
 shrink_dentry_list+0x209/0x310 fs/dcache.c:1292
 prune_dcache_sb+0x119/0x180 fs/dcache.c:1374
 super_cache_scan+0x35f/0x4a0 fs/super.c:225
 do_shrink_slab+0x6d0/0x10e0 mm/shrinker.c:445
 shrink_slab_memcg mm/shrinker.c:562 [inline]
 shrink_slab+0x838/0x1220 mm/shrinker.c:640
 shrink_one+0x2a2/0x730 mm/vmscan.c:5119
 shrink_many mm/vmscan.c:5180 [inline]
 lru_gen_shrink_node mm/vmscan.c:5258 [inline]
 shrink_node+0x35d0/0x3e30 mm/vmscan.c:6247
 kswapd_shrink_node mm/vmscan.c:7101 [inline]
 balance_pgdat mm/vmscan.c:7279 [inline]
 kswapd+0x185e/0x32c0 mm/vmscan.c:7555
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/23 22:22 upstream fe2ec83746e5 0a1606bc .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2026/09/18 19:09 upstream 5dd1818b15d9 853b104b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
* Struck through repros no longer work on HEAD.