WARNING in btrfs_space_info_update_bytes_may_use

Status: upstream: reported syz repro on 2026/10/31 01:02
Reported-by: syzbot+86cdcd346374c0cd8c35@syzkaller.appspotmail.com
First crash: 4d09h, last: 1d10h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in btrfs_space_info_update_bytes_may_use prio:low btrfs -1 syz, C done 5974 1d01h 1465d 0/29 upstream: reported C repro on 2022/10/31 00:15
linux-5.15 WARNING in btrfs_space_info_update_bytes_may_use origin:upstream -1 syz, C error 46 1d08h 1306d 0/3 upstream: reported C repro on 2023/04/07 20:54
linux-6.1 WARNING in btrfs_space_info_update_bytes_may_use origin:upstream -1 syz, C error 461 14h50m 1327d 0/3 upstream: reported C repro on 2023/03/18 05:35

Sample crash report:
BTRFS info (device loop0): last unmount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5930 at fs/btrfs/space-info.h:208 btrfs_space_info_update_bytes_may_use+0x2d6/0x5b0 fs/btrfs/space-info.h:208
Modules linked in:
CPU: 1 PID: 5930 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:btrfs_space_info_update_bytes_may_use+0x2d6/0x5b0 fs/btrfs/space-info.h:208
Code: 35 00 00 74 08 4c 89 ff e8 e7 9a 3d fe 4d 8b 27 4c 89 e7 48 8b 6c 24 18 48 89 ee e8 34 94 e4 fd 49 39 ec 73 1a e8 1a 92 e4 fd <0f> 0b 31 db 43 80 7c 35 00 00 0f 85 6d ff ff ff e9 70 ff ff ff e8
RSP: 0018:ffffc9000330fa10 EFLAGS: 00010293
RAX: ffffffff83a34c86 RBX: ffffffffffea0000 RCX: ffff888029d21e00
RDX: 0000000000000000 RSI: 0000000000160000 RDI: 000000000015f000
RBP: 0000000000160000 R08: ffffffff8f8dda6f R09: 1ffffffff1f1bb4d
R10: dffffc0000000000 R11: fffffbfff1f1bb4e R12: 000000000015f000
R13: 1ffff11005f90310 R14: dffffc0000000000 R15: ffff88802fc81880
FS:  0000555573ebb500(0000) GS:ffff8880b8d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005591beb78fb0 CR3: 0000000032c5f000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 btrfs_space_info_free_bytes_may_use fs/btrfs/space-info.h:241 [inline]
 block_rsv_release_bytes fs/btrfs/block-rsv.c:154 [inline]
 btrfs_block_rsv_release+0x479/0x550 fs/btrfs/block-rsv.c:293
 btrfs_release_global_block_rsv+0x33/0x260 fs/btrfs/block-rsv.c:464
 btrfs_free_block_groups+0xc04/0xe70 fs/btrfs/block-group.c:4511
 close_ctree+0x7de/0xcc0 fs/btrfs/disk-io.c:4474
 generic_shutdown_super+0x134/0x2b0 fs/super.c:690
 kill_anon_super+0x41/0x190 fs/super.c:1314
 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2147
 deactivate_locked_super+0x9c/0x210 fs/super.c:479
 cleanup_mnt+0x3d7/0x460 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:294 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:305
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5254fa0797
Code: a2 c7 05 5c 9f 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd444e3598 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f5254fa0797
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd444e3650
RBP: 00007ffd444e3650 R08: 00007ffd444e4650 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd444e46e0
R13: 00007f5255035f93 R14: 00000000000190fe R15: 00007ffd444e4720
 </TASK>

Crashes (12):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/02 01:48 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/02 23:11 linux-6.6.y b5a1dc3ad482 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/02 23:10 linux-6.6.y b5a1dc3ad482 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/02 23:03 linux-6.6.y b5a1dc3ad482 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/02 22:54 linux-6.6.y b5a1dc3ad482 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:45 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:43 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:42 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:40 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:37 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/11/01 13:34 linux-6.6.y b5a1dc3ad482 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
2026/10/31 01:01 linux-6.6.y b5a1dc3ad482 0ec395f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in btrfs_space_info_update_bytes_may_use
* Struck through repros no longer work on HEAD.