WARNING in bio_alloc_bioset

Status: upstream: reported on 2026/09/04 03:34
Reported-by: syzbot+bb66fed5e80b03b1dd76@syzkaller.appspotmail.com
First crash: 20h59m, last: 20h59m
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 WARNING in bio_alloc_bioset -1 syz, C 4 15h29m 21h53m 0/3 upstream: reported C repro on 2026/09/04 02:39
linux-5.15 WARNING in bio_alloc_bioset -1 syz, C 3 10h44m 20h39m 0/3 upstream: reported C repro on 2026/09/04 03:53
upstream WARNING in bio_alloc_bioset bcachefs -1 syz, C done 22792 441d 510d 29/29 fixed on 2025/08/06 17:37

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5871 at block/bio.c:501 bio_alloc_bioset+0xe10/0x12d0 block/bio.c:501
Modules linked in:
CPU: 1 PID: 5871 Comm: syz.3.8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:bio_alloc_bioset+0xe10/0x12d0 block/bio.c:501
Code: 89 de 81 e6 bf db f6 ff 81 ce 00 20 09 00 e8 57 ca ca fd 48 85 c0 74 69 49 89 c7 e8 9a 27 73 fd e9 0d f7 ff ff e8 90 27 73 fd <0f> 0b e9 58 fa ff ff e8 84 27 73 fd e8 0f 42 ec fc e9 ed fb ff ff
RSP: 0018:ffffc90004bef910 EFLAGS: 00010287
RAX: ffffffff84145ae0 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000d705000 RSI: 0000000000000e17 RDI: 0000000000000e18
RBP: dffffc0000000000 R08: ffff8880764d0a30 R09: 1ffff1100b7de817
R10: dffffc0000000000 R11: ffffed100b7de818 R12: 0000000000069801
R13: ffff8880764d0a30 R14: 0000000000000001 R15: 0000000000000001
FS:  00007fd823f006c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2de21ffe CR3: 000000001ebbf000 CR4: 00000000003526e0
Call Trace:
 <TASK>
 md_super_write+0x11c/0x2f0 drivers/md/md.c:963
 md_update_sb+0x1369/0x2310 drivers/md/md.c:2801
 state_store+0xbf8/0x1b10 drivers/md/md.c:3122
 rdev_attr_store+0x27c/0x420 drivers/md/md.c:3638
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd822f9e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd823f00028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd823225fa0 RCX: 00007fd822f9e159
RDX: 000000000000000c RSI: 0000200000000a00 RDI: 0000000000000007
RBP: 00007fd823035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd823226038 R14: 00007fd823225fa0 R15: 00007ffcccb579e8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/04 03:33 linux-6.6.y 8b73de7da85f 801f0966 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in bio_alloc_bioset
* Struck through repros no longer work on HEAD.