linux-ext4 - [syzbot] [ext4?] WARNING in ext4_write

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Message-ID: <68f12d28.050a0220.1186a4.03dd.GAE@google.com>
Date: Thu, 16 Oct 2025 10:36:40 -0700
From: syzbot <syzbot+070d9738dbe6a10fadc8@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] WARNING in ext4_write_inode (3)

Hello,

syzbot found the following issue on:

HEAD commit:    67029a49db6c Merge tag 'trace-v6.18-3' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165f3304580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c2d7b4143707d3a0
dashboard link: https://syzkaller.appspot.com/bug?extid=070d9738dbe6a10fadc8
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-67029a49.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/462968d248b4/vmlinux-67029a49.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9b7dac7b9874/bzImage-67029a49.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+070d9738dbe6a10fadc8@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 78 at fs/ext4/inode.c:5698 ext4_write_inode+0x545/0x620 fs/ext4/inode.c:5698
Modules linked in:
CPU: 0 UID: 0 PID: 78 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~bpo12+1 04/01/2014
RIP: 0010:ext4_write_inode+0x545/0x620 fs/ext4/inode.c:5698
Code: 8b 05 cf b4 18 10 48 3b 44 24 30 75 5a 44 89 e0 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 1c 18 47 ff 90 <0f> 0b 90 eb cf e8 11 18 47 ff 41 bc fb ff ff ff eb c2 e8 04 18 47
RSP: 0018:ffffc9000102ec60 EFLAGS: 00010293
RAX: ffffffff82793b74 RBX: 0000000000000800 RCX: ffff88801fbec900
RDX: 0000000000000000 RSI: 0000000000000800 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffffffff8f9e3177 R09: 1ffffffff1f3c62e
R10: dffffc0000000000 R11: ffffffff82793630 R12: 0000000000000000
R13: ffff888036b70298 R14: ffff888036b70298 R15: ffff88801fbec900
FS:  0000000000000000(0000) GS:ffff88808d301000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcf30301010 CR3: 000000000df38000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 write_inode fs/fs-writeback.c:1564 [inline]
 __writeback_single_inode+0x6f1/0xff0 fs/fs-writeback.c:1784
 writeback_single_inode+0x1f9/0x6a0 fs/fs-writeback.c:1840
 write_inode_now+0x160/0x1d0 fs/fs-writeback.c:2903
 iput_final fs/inode.c:1901 [inline]
 iput+0x830/0xc50 fs/inode.c:1966
 __dentry_kill+0x209/0x660 fs/dcache.c:669
 dput+0x19f/0x2b0 fs/dcache.c:911
 ovl_destroy_inode+0x42/0x150 fs/overlayfs/super.c:209
 destroy_inode fs/inode.c:396 [inline]
 evict+0x7c2/0x9c0 fs/inode.c:834
 __dentry_kill+0x209/0x660 fs/dcache.c:669
 shrink_kill+0xa9/0x2c0 fs/dcache.c:1114
 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141
 prune_dcache_sb+0x10e/0x180 fs/dcache.c:1222
 super_cache_scan+0x369/0x4b0 fs/super.c:222
 do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
 shrink_slab_memcg mm/shrinker.c:550 [inline]
 shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
 shrink_one+0x28a/0x7c0 mm/vmscan.c:4955
 shrink_many mm/vmscan.c:5016 [inline]
 lru_gen_shrink_node mm/vmscan.c:5094 [inline]
 shrink_node+0x315d/0x3780 mm/vmscan.c:6081
 kswapd_shrink_node mm/vmscan.c:6941 [inline]
 balance_pgdat mm/vmscan.c:7124 [inline]
 kswapd+0x147c/0x2800 mm/vmscan.c:7389
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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