Re: [syzbot] [ext4?] WARNING in __folio_mark_dirty (3)

[syzbot <syzbot+b0a0670332b6b3230a0a@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in __folio_mark_dirty

------------[ cut here ]------------
WARNING: CPU: 1 PID: 6740 at mm/page-writeback.c:2716 __folio_mark_dirty+0x1fb/0xe20 mm/page-writeback.c:2716
Modules linked in:
CPU: 1 UID: 0 PID: 6740 Comm: syz.0.31 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__folio_mark_dirty+0x1fb/0xe20 mm/page-writeback.c:2716
Code: 3c 38 00 74 08 48 89 df e8 d2 a1 26 00 4c 8b 33 4c 89 f6 48 83 e6 08 31 ff e8 71 ef c4 ff 49 83 e6 08 75 1c e8 06 ea c4 ff 90 <0f> 0b 90 eb 16 e8 fb e9 c4 ff e9 7e 07 00 00 e8 f1 e9 c4 ff eb 05
RSP: 0018:ffffc90003a979d0 EFLAGS: 00010293
RAX: ffffffff81f9d61a RBX: ffffea0001056b40 RCX: ffff888020775a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff9400020ad69 R12: ffff88805b014d00
R13: ffff88805b014cf8 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555575052500(0000) GS:ffff888126ef6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000440 CR3: 0000000036d66000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 block_dirty_folio+0x17a/0x1d0 fs/buffer.c:754
 fault_dirty_shared_page+0x103/0x570 mm/memory.c:3518
 wp_page_shared mm/memory.c:3905 [inline]
 do_wp_page+0x263e/0x4930 mm/memory.c:4108
 handle_pte_fault mm/memory.c:6193 [inline]
 __handle_mm_fault mm/memory.c:6318 [inline]
 handle_mm_fault+0x97c/0x3400 mm/memory.c:6487
 do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f1eba837398
Code: fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 fa 7f 4c 17 f0 c3 66 0f 1f 84 00 00 00 00 00 48 8b 4c 16 f8 48 8b 36 <48> 89 37 48 89 4c 17 f8 c3 c5 fe 6f 54 16 e0 c5 fe 6f 5c 16 c0 c5
RSP: 002b:00007ffd39d5fc68 EFLAGS: 00010246
RAX: 0000200000000440 RBX: 0000000000000004 RCX: 0030656c69662f2e
RDX: 0000000000000008 RSI: 0030656c69662f2e RDI: 0000200000000440
RBP: 00007f1ebaac7da0 R08: 0000001b2cc20000 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000009 R12: 00007f1ebaac5fac
R13: 00007f1ebaac5fa0 R14: fffffffffffffffe R15: 00007ffd39d5fd80
 </TASK>


Tested on:

commit:         6fb67ac8 ext4: drop the TODO comment in ext4_es_insert..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
console output: https://syzkaller.appspot.com/x/log.txt?x=16156192580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=41ad820f608cb833
dashboard link: https://syzkaller.appspot.com/bug?extid=b0a0670332b6b3230a0a
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.