Re: WARNING in __btrfs_update_delayed_inode

[Qu Wenruo]

On 2021/9/14 上午10:11, Hao Sun wrote:
> Hello,
>
> When using Healer to fuzz the latest Linux kernel, the following crash
> was triggered.

Hey, it's a warning, not a crash.

> HEAD commit: 6880fa6c5660 Linux 5.15-rc1
> git tree: upstream
> console output:
> https://drive.google.com/file/d/1nhxxAfMLAbaBRaJdyjKU56syabhlgjsO/view?usp=sharing
> kernel config: https://drive.google.com/file/d/1rUzyMbe5vcs6khA3tL9EHTLJvsUdWcgB/view?usp=sharing
> Syzlang reproducer:
> https://drive.google.com/file/d/15RurS3tTTpzu-fdhlQYS-qY_vpx5RoFX/view?usp=sharing
>
> Sorry, I don't have a C reproducer for this crash but have a Syzlang
> reproducer. Also, hope the symbolized report can help.
> Here are the instructions on how to execute Syzlang prog:
> https://github.com/google/syzkaller/blob/master/docs/executing_syzkaller_programs.md
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>
>
> FAULT_INJECTION: forcing a failure.
> name failslab, interval 1, probability 0, space 0, times 0
> CPU: 3 PID: 7821 Comm: syz-executor Not tainted 5.15.0-rc1 #16
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> Call Trace:
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x8d/0xcf lib/dump_stack.c:106
>   fail_dump lib/fault-inject.c:52 [inline]
>   should_fail+0x13c/0x160 lib/fault-inject.c:146
>   should_failslab+0x5/0x10 mm/slab_common.c:1328
>   slab_pre_alloc_hook.constprop.99+0x4e/0xc0 mm/slab.h:494
>   slab_alloc_node mm/slub.c:3120 [inline]
>   slab_alloc mm/slub.c:3214 [inline]
>   kmem_cache_alloc+0x44/0x280 mm/slub.c:3219
>   btrfs_alloc_delayed_extent_op fs/btrfs/delayed-ref.h:299 [inline]
>   btrfs_alloc_tree_block+0x38c/0x670 fs/btrfs/extent-tree.c:4833
>   __btrfs_cow_block+0x16f/0x7d0 fs/btrfs/ctree.c:415
>   btrfs_cow_block+0x12a/0x300 fs/btrfs/ctree.c:570
>   btrfs_search_slot+0x6b0/0xee0 fs/btrfs/ctree.c:1768
>   btrfs_lookup_inode+0x50/0x110 fs/btrfs/inode-item.c:408
>   __btrfs_update_delayed_inode+0x81/0x370 fs/btrfs/delayed-inode.c:948
>   btrfs_commit_inode_delayed_inode+0x14a/0x160 fs/btrfs/delayed-inode.c:1189
>   btrfs_log_inode+0x438/0x1ab0 fs/btrfs/tree-log.c:5385
>   btrfs_log_inode_parent+0x272/0x1110 fs/btrfs/tree-log.c:6168
>   btrfs_log_dentry_safe+0x3a/0x50 fs/btrfs/tree-log.c:6269
>   btrfs_sync_file+0x2cd/0x760 fs/btrfs/file.c:2264
>   vfs_fsync_range+0x48/0xa0 fs/sync.c:200
>   generic_write_sync include/linux/fs.h:2955 [inline]
>   btrfs_file_write_iter+0x34f/0x510 fs/btrfs/file.c:2034
>   call_write_iter include/linux/fs.h:2163 [inline]
>   new_sync_write+0x18d/0x260 fs/read_write.c:507
>   vfs_write+0x43b/0x4a0 fs/read_write.c:594
>   ksys_write+0xd2/0x120 fs/read_write.c:647
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x46ae99
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f040bcc8c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 000000000078c158 RCX: 000000000046ae99
> RDX: 000000000000001b RSI: 0000000020005a00 RDI: 0000000000000008
> RBP: 00007f040bcc8c80 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000002c
> R13: 0000000000000000 R14: 000000000078c158 R15: 00007ffcfffddd60
> ------------[ cut here ]------------
> WARNING: CPU: 3 PID: 7821 at fs/btrfs/delayed-inode.c:995

Any error causing btrfs to abort transaction (except -EIO) will cause
btrfs to output extra waing messages for debug purpose.

So all these warnings are *expected*.

Thanks,
Qu

> __btrfs_update_delayed_inode+0x318/0x370 fs/btrfs/delayed-inode.c:995
> Modules linked in:
> CPU: 3 PID: 7821 Comm: syz-executor Not tainted 5.15.0-rc1 #16
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> RIP: 0010:__btrfs_update_delayed_inode+0x318/0x370 fs/btrfs/delayed-inode.c:995
> Code: a8 c8 19 00 00 03 72 24 e8 f5 26 43 ff 83 fd fb 74 3f 83 fd e2
> 74 3a e8 e6 26 43 ff 89 ee 48 c7 c7 38 25 39 85 e8 08 2e 2e ff <0f> 0b
> e8 d1 26 43 ff 89 e9 ba e3 03 00 00 4c 89 f7 48 c7 c6 70 39
> RSP: 0018:ffffc9000b13ba28 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: ffff88810a46b090 RCX: ffffc90002791000
> RDX: 0000000000040000 RSI: ffffffff812d18bc RDI: 00000000ffffffff
> RBP: 00000000fffffff4 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffc9000b13b840 R11: 0000000000000007 R12: ffff88810e51eb60
> R13: 00000000fffffff4 R14: ffff88810248f0d0 R15: ffff888111df8000
> FS:  00007f040bcc9700(0000) GS:ffff88813dd00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000400200 CR3: 000000010e5d6000 CR4: 0000000000750ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>   btrfs_commit_inode_delayed_inode+0x14a/0x160 fs/btrfs/delayed-inode.c:1189
>   btrfs_log_inode+0x438/0x1ab0 fs/btrfs/tree-log.c:5385
>   btrfs_log_inode_parent+0x272/0x1110 fs/btrfs/tree-log.c:6168
>   btrfs_log_dentry_safe+0x3a/0x50 fs/btrfs/tree-log.c:6269
>   btrfs_sync_file+0x2cd/0x760 fs/btrfs/file.c:2264
>   vfs_fsync_range+0x48/0xa0 fs/sync.c:200
>   generic_write_sync include/linux/fs.h:2955 [inline]
>   btrfs_file_write_iter+0x34f/0x510 fs/btrfs/file.c:2034
>   call_write_iter include/linux/fs.h:2163 [inline]
>   new_sync_write+0x18d/0x260 fs/read_write.c:507
>   vfs_write+0x43b/0x4a0 fs/read_write.c:594
>   ksys_write+0xd2/0x120 fs/read_write.c:647
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x46ae99
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f040bcc8c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 000000000078c158 RCX: 000000000046ae99
> RDX: 000000000000001b RSI: 0000000020005a00 RDI: 0000000000000008
> RBP: 00007f040bcc8c80 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000002c
> R13: 0000000000000000 R14: 000000000078c158 R15: 00007ffcfffddd60