Re: [Bug] v6.15+: kernel panic when mount & umount btrfs

[Qu Wenruo <wqu@suse.com>]

在 2025/5/27 13:36, Ming Lei 写道:
> Hello,
> 
> Just try the latest linus tree by running `rublk` builtin test on
> Fedora, and found
> the following panic:
> 
> git clone https://github.com/ublk-org/rublk
> cd rublk
> cargo test

There is a bug in commit 5e121ae687b8 ("btrfs: use buffer xarray for 
extent buffer writeback operations"), and there is already a fix queued 
for the next pull request:

https://lore.kernel.org/linux-btrfs/b964b92f482453cbd122743995ff23aa7158b2cb.1747677774.git.josef@toxicpanda.com/

Thanks,
Qu


> 
> 
> [   24.153674] BTRFS: device fsid b99703ee-349d-40fa-b3d6-b5b451f979ab
> devid 1 transid 8 /dev/ublkb1 (259:3) scanned by moun)
> [   24.154624] BTRFS info (device ublkb1): first mount of filesystem
> b99703ee-349d-40fa-b3d6-b5b451f979ab
> [   24.155123] BTRFS info (device ublkb1): using crc32c (crc32c-x86)
> checksum algorithm
> [   24.155777] BTRFS info (device ublkb1): using free-space-tree
> [   24.157502] BTRFS info (device ublkb1): host-managed zoned block
> device /dev/ublkb1, 256 zones of 4194304 bytes
> [   24.158503] BTRFS info (device ublkb1): zoned mode enabled with
> zone size 4194304
> [   24.159541] BTRFS info (device ublkb1): checking UUID tree
> [   24.166324] EXT4-fs (ublkb5): mounted filesystem
> ae8f9776-4cb7-4edd-9acd-44291433e146 r/w with ordered data mode. Quota
> mode: none.
> [   24.169139] EXT4-fs (ublkb8): mounted filesystem
> 4beadbbc-d9c3-484d-b37b-8ea7ceb4cade r/w with ordered data mode. Quota
> mode: none.
> [   24.171259] EXT4-fs (ublkb5): unmounting filesystem
> ae8f9776-4cb7-4edd-9acd-44291433e146.
> [   24.173862] EXT4-fs (ublkb8): unmounting filesystem
> 4beadbbc-d9c3-484d-b37b-8ea7ceb4cade.
> [   24.336068] ------------[ cut here ]------------
> [   24.336449] kernel BUG at fs/btrfs/extent_io.c:2776!
> [   24.336786] Oops: invalid opcode: 0000 [#1] SMP NOPTI
> [   24.337064] CPU: 7 UID: 0 PID: 119 Comm: kworker/u64:2 Not tainted
> 6.15.0+ #279 PREEMPT(full)
> [   24.337530] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
> BIOS 1.16.3-1.fc39 04/01/2014
> [   24.337985] Workqueue: writeback wb_workfn (flush-btrfs-2)
> [   24.338293] RIP: 0010:detach_extent_buffer_folio+0xca/0xd0
> [   24.338595] Code: 4d 34 74 18 84 db 74 96 4d 8d 75 7c 5b 4c 89 f7
> 5d 41 5c 41 5d 41 5e e9 54 f7 aa 00 48 89 ef e8 8c 48 d0 ff eb de 0f
> 0b0
> [   24.339599] RSP: 0018:ffffd34500477880 EFLAGS: 00010202
> [   24.339887] RAX: 0017ffffc000400a RBX: 0000000000000001 RCX: ffffd34500477838
> [   24.340280] RDX: 0000000000000001 RSI: fffff5a2442fb280 RDI: ffff8bf88590ef74
> [   24.340697] RBP: fffff5a2442fb280 R08: 0000000000000024 R09: 0000000000000000
> [   24.341143] R10: 0000000000000001 R11: ffff8bf896b39500 R12: ffff8bf88de8cd20
> [   24.341597] R13: ffff8bf88590eef8 R14: ffff8bf88590ef74 R15: ffffd34500477970
> [   24.342106] FS:  0000000000000000(0000) GS:ffff8bfd3ffb6000(0000)
> knlGS:0000000000000000
> [   24.342739] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   24.343087] CR2: 00007f55e0cdff10 CR3: 00000002af824002 CR4: 0000000000772ef0
> [   24.343504] PKRU: 55555554
> [   24.343667] Call Trace:
> [   24.343823]  <TASK>
> [   24.343956]  release_extent_buffer+0x9b/0xd0
> [   24.344209]  btree_write_cache_pages+0x1de/0x590
> [   24.344486]  do_writepages+0xc8/0x170
> [   24.344707]  __writeback_single_inode+0x41/0x340
> [   24.344979]  writeback_sb_inodes+0x21b/0x4e0
> [   24.345234]  wb_writeback+0x98/0x330
> [   24.345449]  wb_workfn+0xc2/0x450
> [   24.345648]  ? try_to_wake_up+0x308/0x740
> [   24.346052]  process_one_work+0x188/0x340
> [   24.346445]  worker_thread+0x257/0x3a0
> [   24.346811]  ? __pfx_worker_thread+0x10/0x10
> [   24.347206]  kthread+0xfc/0x240
> [   24.347560]  ? __pfx_kthread+0x10/0x10
> [   24.347924]  ret_from_fork+0x34/0x50
> [   24.348284]  ? __pfx_kthread+0x10/0x10
> [   24.348672]  ret_from_fork_asm+0x1a/0x30
> [   24.349046]  </TASK>
> [   24.349344] Modules linked in: iscsi_tcp libiscsi_tcp libiscsi
> scsi_transport_iscsi target_core_pscsi target_core_file
> target_core_iblockg
> [   24.353785] Dumping ftrace buffer:
> [   24.354170]    (ftrace buffer empty)
> [   24.354584] ---[ end trace 0000000000000000 ]---
> [   24.355021] RIP: 0010:detach_extent_buffer_folio+0xca/0xd0
> [   24.355525] Code: 4d 34 74 18 84 db 74 96 4d 8d 75 7c 5b 4c 89 f7
> 5d 41 5c 41 5d 41 5e e9 54 f7 aa 00 48 89 ef e8 8c 48 d0 ff eb de 0f
> 0b0
> [   24.357039] RSP: 0018:ffffd34500477880 EFLAGS: 00010202
> [   24.357571] RAX: 0017ffffc000400a RBX: 0000000000000001 RCX: ffffd34500477838
> [   24.358183] RDX: 0000000000000001 RSI: fffff5a2442fb280 RDI: ffff8bf88590ef74
> [   24.358807] RBP: fffff5a2442fb280 R08: 0000000000000024 R09: 0000000000000000
> [   24.359443] R10: 0000000000000001 R11: ffff8bf896b39500 R12: ffff8bf88de8cd20
> [   24.360070] R13: ffff8bf88590eef8 R14: ffff8bf88590ef74 R15: ffffd34500477970
> [   24.360746] FS:  0000000000000000(0000) GS:ffff8bfd3ffb6000(0000)
> knlGS:0000000000000000
> [   24.361451] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   24.362055] CR2: 00007f55e0cdff10 CR3: 00000002af824002 CR4: 0000000000772ef0
> [   24.362812] PKRU: 55555554
> [   24.363145] Kernel panic - not syncing: Fatal exception
> [   24.363845] Dumping ftrace buffer:
> [   24.364213]    (ftrace buffer empty)
> [   24.364602] Kernel Offset: 0x27000000 from 0xffffffff81000000
> (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
> [   24.365385] ---[ end Kernel panic - not syncing: Fatal exception ]---
> 
> Thanks,
> 
>