Re: [moderation/CI] Re: fs: support freeze/thaw/mark_dead/sync with shared devices

#syz upstream

On Tue, Jun 2, 2026 at 5:14 PM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v1] fs: support freeze/thaw/mark_dead/sync with shared devices
> https://lore.kernel.org/all/20260602-work-super-bdev_holder_global-v1-0-bb0fd82f3861@kernel.org
> * [PATCH RFC 1/8] fs, block: move blk_mode_t and fop_flags_t into <linux/types.h>
> * [PATCH RFC 2/8] fs: add a global device to super block hash table
> * [PATCH RFC 3/8] fs: refuse to claim any frozen block device
> * [PATCH RFC 4/8] xfs: port to fs_bdev_file_open_by_path()
> * [PATCH RFC 5/8] btrfs: open via dedicated fs bdev helpers
> * [PATCH RFC 6/8] ext4: open via dedicated fs bdev helpers
> * [PATCH RFC 7/8] erofs: open via dedicated fs bdev helpers
> * [PATCH RFC 8/8] super: make fs_holder_ops private
>
> and found the following issue:
> general protection fault in close_fs_devices
>
> Full report is available here:
> https://ci.syzbot.org/series/9511f00a-a3c2-44ab-9a0b-2d65de5bbd49
>
> ***
>
> general protection fault in close_fs_devices
>
> tree:      bpf-next
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
> base:      254f49634ee16a731174d2ae34bc50bd5f45e731
> arch:      amd64
> compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:    https://ci.syzbot.org/builds/4af26755-5773-453e-807d-ee451d2fdec5/config
> syz repro: https://ci.syzbot.org/findings/2d8d96f7-d133-47dc-b4ca-5c0c65e1b6c9/syz_repro
>
> btrfs: Deprecated parameter 'usebackuproot'
> BTRFS warning: 'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead
> BTRFS: device fsid ed167579-eb65-4e76-9a50-61ac97e9b59d devid 1281 transid 8 /dev/loop1 (7:1) scanned by syz.1.18 (5863)
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000000f8: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x00000000000007c0-0x00000000000007c7]
> CPU: 1 UID: 0 PID: 5863 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:btrfs_close_bdev fs/btrfs/volumes.c:1140 [inline]
> RIP: 0010:btrfs_close_one_device fs/btrfs/volumes.c:1161 [inline]
> RIP: 0010:close_fs_devices+0x47c/0x860 fs/btrfs/volumes.c:1204
> Code: 3c 08 00 74 08 48 89 ef e8 b1 95 38 fe 48 8b 6d 00 b8 c0 07 00 00 48 01 c5 48 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 ef e8 86 95 38 fe 48 8b 75 00 4c 89 ff e8
> RSP: 0018:ffffc90004007a48 EFLAGS: 00010202
> RAX: 00000000000000f8 RBX: 1ffff110368c440b RCX: dffffc0000000000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 00000000000007c0 R08: ffff8881b462206f R09: 1ffff110368c440d
> R10: dffffc0000000000 R11: ffffed10368c440e R12: ffff8881b4622000
> R13: ffff8881b4622068 R14: ffff8881b4622058 R15: ffff8881707b7a00
> FS:  00007f849d6ce6c0(0000) GS:ffff8882a9292000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f849c786a00 CR3: 00000001bbbcc000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  btrfs_close_devices+0xcd/0x570 fs/btrfs/volumes.c:1219
>  btrfs_free_fs_info+0x4f/0x360 fs/btrfs/disk-io.c:1205
>  deactivate_locked_super+0xbc/0x130 fs/super.c:477
>  btrfs_get_tree_super fs/btrfs/super.c:-1 [inline]
>  btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline]
>  btrfs_get_tree+0xca6/0x1910 fs/btrfs/super.c:2121
>  vfs_get_tree+0x92/0x2a0 fs/super.c:1928
>  fc_mount fs/namespace.c:1193 [inline]
>  do_new_mount_fc fs/namespace.c:3758 [inline]
>  do_new_mount+0x341/0xd30 fs/namespace.c:3834
>  do_mount fs/namespace.c:4167 [inline]
>  __do_sys_mount fs/namespace.c:4383 [inline]
>  __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f849c79e0ca
> Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f849d6cde58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007f849d6cdee0 RCX: 00007f849c79e0ca
> RDX: 00002000000055c0 RSI: 0000200000000340 RDI: 00007f849d6cdea0
> RBP: 00002000000055c0 R08: 00007f849d6cdee0 R09: 0000000000000408
> R10: 0000000000000408 R11: 0000000000000246 R12: 0000200000000340
> R13: 00007f849d6cdea0 R14: 00000000000055f5 R15: 0000200000000380
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:btrfs_close_bdev fs/btrfs/volumes.c:1140 [inline]
> RIP: 0010:btrfs_close_one_device fs/btrfs/volumes.c:1161 [inline]
> RIP: 0010:close_fs_devices+0x47c/0x860 fs/btrfs/volumes.c:1204
> Code: 3c 08 00 74 08 48 89 ef e8 b1 95 38 fe 48 8b 6d 00 b8 c0 07 00 00 48 01 c5 48 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 ef e8 86 95 38 fe 48 8b 75 00 4c 89 ff e8
> RSP: 0018:ffffc90004007a48 EFLAGS: 00010202
>
> RAX: 00000000000000f8 RBX: 1ffff110368c440b RCX: dffffc0000000000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 00000000000007c0 R08: ffff8881b462206f R09: 1ffff110368c440d
> R10: dffffc0000000000 R11: ffffed10368c440e R12: ffff8881b4622000
> R13: ffff8881b4622068 R14: ffff8881b4622058 R15: ffff8881707b7a00
> FS:  00007f849d6ce6c0(0000) GS:ffff8882a9292000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000557941c2b058 CR3: 00000001bbbcc000 CR4: 00000000000006f0
> ----------------
> Code disassembly (best guess):
>    0:   3c 08                   cmp    $0x8,%al
>    2:   00 74 08 48             add    %dh,0x48(%rax,%rcx,1)
>    6:   89 ef                   mov    %ebp,%edi
>    8:   e8 b1 95 38 fe          call   0xfe3895be
>    d:   48 8b 6d 00             mov    0x0(%rbp),%rbp
>   11:   b8 c0 07 00 00          mov    $0x7c0,%eax
>   16:   48 01 c5                add    %rax,%rbp
>   19:   48 89 e8                mov    %rbp,%rax
>   1c:   48 c1 e8 03             shr    $0x3,%rax
>   20:   48 b9 00 00 00 00 00    movabs $0xdffffc0000000000,%rcx
>   27:   fc ff df
> * 2a:   80 3c 08 00             cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
>   2e:   74 08                   je     0x38
>   30:   48 89 ef                mov    %rbp,%rdi
>   33:   e8 86 95 38 fe          call   0xfe3895be
>   38:   48 8b 75 00             mov    0x0(%rbp),%rsi
>   3c:   4c 89 ff                mov    %r15,%rdi
>   3f:   e8                      .byte 0xe8
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: [email protected]
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at [email protected].
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
> Note: arguments like custom git repos and branches are not supported.
>
> The email will later be sent to:
> [[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]]
>
> If the report looks fine to you, reply with:
> #syz upstream
>
> If the report is a false positive, reply with
> #syz invalid
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion visit https://groups.google.com/d/msgid/syzkaller-upstream-moderation/6a1ef366.278b5b03.2bcf39.003f.GAE%40google.com.