Re: [syzbot] [btrfs?] kernel BUG in __folio_start_writeback

[syzbot <syzbot+aac7bff85be224de5156@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in __folio_start_writeback

 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 get_signal+0x16a3/0x1740 kernel/signal.c:2918
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
------------[ cut here ]------------
kernel BUG at mm/page-writeback.c:3119!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 3538 Comm: kworker/u8:10 Not tainted 6.12.0-rc7-syzkaller-00132-g21865e0dd679 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: btrfs-delalloc btrfs_work_helper
RIP: 0010:__folio_start_writeback+0xc06/0x1050 mm/page-writeback.c:3119
Code: 25 ff 0f 00 00 0f 84 d3 00 00 00 e8 14 79 c4 ff e9 ba f5 ff ff e8 0a 79 c4 ff 4c 89 f7 48 c7 c6 c0 0e f4 8b e8 6b 46 0d 00 90 <0f> 0b e8 f3 78 c4 ff 4c 89 f7 48 c7 c6 20 15 f4 8b e8 54 46 0d 00
RSP: 0018:ffffc9000ca9f500 EFLAGS: 00010246
RAX: 258fc5bd6608dc00 RBX: 0000000000000002 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffffffff8beacb20 RDI: 0000000000000001
RBP: ffffc9000ca9f670 R08: ffffffff94059917 R09: 1ffffffff280b322
R10: dffffc0000000000 R11: fffffbfff280b323 R12: 0000000000000000
R13: 1ffff92001953eac R14: ffffea0001c40500 R15: ffff888073b564f8
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0002adb80 CR3: 0000000027072000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 process_one_folio fs/btrfs/extent_io.c:187 [inline]
 __process_folios_contig+0x31c/0x540 fs/btrfs/extent_io.c:216
 submit_one_async_extent fs/btrfs/inode.c:1229 [inline]
 submit_compressed_extents+0xdb3/0x16e0 fs/btrfs/inode.c:1632
 run_ordered_work fs/btrfs/async-thread.c:245 [inline]
 btrfs_work_helper+0x56b/0xc50 fs/btrfs/async-thread.c:324
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__folio_start_writeback+0xc06/0x1050 mm/page-writeback.c:3119
Code: 25 ff 0f 00 00 0f 84 d3 00 00 00 e8 14 79 c4 ff e9 ba f5 ff ff e8 0a 79 c4 ff 4c 89 f7 48 c7 c6 c0 0e f4 8b e8 6b 46 0d 00 90 <0f> 0b e8 f3 78 c4 ff 4c 89 f7 48 c7 c6 20 15 f4 8b e8 54 46 0d 00
RSP: 0018:ffffc9000ca9f500 EFLAGS: 00010246
RAX: 258fc5bd6608dc00 RBX: 0000000000000002 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffffffff8beacb20 RDI: 0000000000000001
RBP: ffffc9000ca9f670 R08: ffffffff94059917 R09: 1ffffffff280b322
R10: dffffc0000000000 R11: fffffbfff280b323 R12: 0000000000000000
R13: 1ffff92001953eac R14: ffffea0001c40500 R15: ffff888073b564f8
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fabe0e31440 CR3: 0000000032718000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


Tested on:

commit:         21865e0d btrfs: use PTR_ERR() instead of PTR_ERR_OR_ZE..
git tree:       https://github.com/btrfs/linux.git for-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10835778580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fa4954ad2c62b915
dashboard link: https://syzkaller.appspot.com/bug?extid=aac7bff85be224de5156
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.