Re: [syzbot] [btrfs?] kernel BUG in __extent_writepage_io (2)

Qu Wenruo
2024-08-28T22:59:46Z

在 2024/8/29 08:04, syzbot 写道:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: d2bafcf224f3 Merge tag 'cgroup-for-6.11-rc4-fixes' of git:..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12d5fa7b980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=4fc2afd52fd008bb
> dashboard link: https://syzkaller.appspot.com/bug?extid=ba3c0273042a898c230e
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=137c040b980000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ddb015980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/7569f02310fb/disk-d2bafcf2.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e30fee7b6c1d/vmlinux-d2bafcf2.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2ffddebac153/bzImage-d2bafcf2.xz
> mounted in repro #1: https://storage.googleapis.com/syzbot-assets/cd08557ae343/mount_0.gz
> mounted in repro #2: https://storage.googleapis.com/syzbot-assets/90ff8392fe84/mount_2.gz
> mounted in repro #3: https://storage.googleapis.com/syzbot-assets/9c5b91850930/mount_7.gz
>
> The issue was bisected to:
>
> commit f22b5dcbd71edea087946511554956591557de9a
> Author: Christoph Hellwig <hch@lst.de>
> Date: Wed May 31 06:04:59 2023 +0000
>
> btrfs: remove non-standard extent handling in __extent_writepage_io
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10974043980000
> final oops: https://syzkaller.appspot.com/x/report.txt?x=12974043980000
> console output: https://syzkaller.appspot.com/x/log.txt?x=14974043980000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+ba3c0273042a898c230e@syzkaller.appspotmail.com
> Fixes: f22b5dcbd71e ("btrfs: remove non-standard extent handling in __extent_writepage_io")
>
> assertion failed: block_start != EXTENT_MAP_HOLE, in fs/btrfs/extent_io.c:1488

This means there is a dirty page range for us to writeback, but no
delalloc range for it.

That patch is not the cause, but only exposed it.

I guess there is some page fault involved or interrupted direct IO?

Anyway the bisection doesn't make much sense.

Thanks,
Qu

> ------------[ cut here ]------------
> kernel BUG at fs/btrfs/extent_io.c:1488!
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> CPU: 1 UID: 0 PID: 5722 Comm: syz-executor399 Not tainted 6.11.0-rc4-syzkaller-00255-gd2bafcf224f3 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
> RIP: 0010:__extent_writepage_io+0x1224/0x1400 fs/btrfs/extent_io.c:1488
> Code: f7 07 90 0f 0b e8 dc 68 df fd 48 c7 c7 e0 92 2c 8c 48 c7 c6 c0 a0 2c 8c 48 c7 c2 80 92 2c 8c b9 d0 05 00 00 e8 9d 15 f7 07 90 <0f> 0b e8 b5 68 df fd 48 8b 3c 24 e8 bc 9d ff ff 48 89 c7 48 c7 c6
> RSP: 0018:ffffc900097d6ee8 EFLAGS: 00010246
> RAX: 000000000000004e RBX: 0000000000000000 RCX: 2f9fd79be1350f00
> RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
> RBP: dffffc0000000000 R08: ffffffff817402ac R09: 1ffff920012fad7c
> R10: dffffc0000000000 R11: fffff520012fad7d R12: ffffea0001ccbdc8
> R13: 1ffffd40003997b9 R14: fffffffffffffffd R15: 000000000007b000
> FS: 00007f11a84976c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f11a0fff000 CR3: 0000000020e4c000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> __extent_writepage fs/btrfs/extent_io.c:1578 [inline]
> extent_write_cache_pages fs/btrfs/extent_io.c:2251 [inline]
> btrfs_writepages+0x12a2/0x2760 fs/btrfs/extent_io.c:2373
> do_writepages+0x35d/0x870 mm/page-writeback.c:2683
> filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:397
> __filemap_fdatawrite_range mm/filemap.c:430 [inline]
> filemap_fdatawrite_range+0x120/0x180 mm/filemap.c:448
> btrfs_fdatawrite_range+0x53/0xe0 fs/btrfs/file.c:3794
> btrfs_direct_write+0x558/0xb40 fs/btrfs/direct-io.c:952
> btrfs_do_write_iter+0x2a1/0x760 fs/btrfs/file.c:1505
> do_iter_readv_writev+0x60a/0x890
> vfs_writev+0x37c/0xbb0 fs/read_write.c:971
> do_pwritev fs/read_write.c:1072 [inline]
> __do_sys_pwritev2 fs/read_write.c:1131 [inline]
> __se_sys_pwritev2+0x1ca/0x2d0 fs/read_write.c:1122
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f11a850bd79
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 1d 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f11a8497158 EFLAGS: 00000212 ORIG_RAX: 0000000000000148
> RAX: ffffffffffffffda RBX: 00007f11a85916d8 RCX: 00007f11a850bd79
> RDX: 0000000000000001 RSI: 0000000020000240 RDI: 0000000000000004
> RBP: 00007f11a85916d0 R08: 0000000000000000 R09: 0000000000000003
> R10: 0000000000002000 R11: 0000000000000212 R12: 00007f11a85916dc
> R13: 000000000000006e R14: 00007ffd9dcad860 R15: 00007ffd9dcad948
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__extent_writepage_io+0x1224/0x1400 fs/btrfs/extent_io.c:1488
> Code: f7 07 90 0f 0b e8 dc 68 df fd 48 c7 c7 e0 92 2c 8c 48 c7 c6 c0 a0 2c 8c 48 c7 c2 80 92 2c 8c b9 d0 05 00 00 e8 9d 15 f7 07 90 <0f> 0b e8 b5 68 df fd 48 8b 3c 24 e8 bc 9d ff ff 48 89 c7 48 c7 c6
> RSP: 0018:ffffc900097d6ee8 EFLAGS: 00010246
> RAX: 000000000000004e RBX: 0000000000000000 RCX: 2f9fd79be1350f00
> RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
> RBP: dffffc0000000000 R08: ffffffff817402ac R09: 1ffff920012fad7c
> R10: dffffc0000000000 R11: fffff520012fad7d R12: ffffea0001ccbdc8
> R13: 1ffffd40003997b9 R14: fffffffffffffffd R15: 000000000007b000
> FS: 00007f11a84976c0(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005654e2821068 CR3: 0000000020e4c000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> This report is generated by a bot. It may contain errors.
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