WARNING: locking bug in __refill_objects_node

Status: upstream: reported C repro on 2026/10/26 10:19
Subsystems: kvm
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+f11512d1e5878ba5e60e@syzkaller.appspotmail.com
First crash: 10d, last: 7d01h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
4b64cbe7 repro-c Reproduced: ✅ ❓ WARNING: locking bug in __refill_objects_node 2026/10/19 17:22 2026/10/19 17:22 2026/10/19 20:05 e931f328
980c8566 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ✅ ❓ WARNING: locking bug in __refill_objects_node 2026/10/18 01:07 2026/10/18 01:07 2026/10/18 02:09 432c0077
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly kvm report (Oct 2026) 0 (1) 2026/10/26 12:33
[syzbot] [kvm?] WARNING: locking bug in __refill_objects_node 0 (1) 2026/10/26 10:19
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/10/19 20:05 13m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c03c1a14507dfaf8b856c2608f9ac216021fc222 report job log log

Sample crash report:
=============================
[ BUG: Invalid wait context ]
syzkaller #0 Tainted: G S                 
-----------------------------
syz-executor177/6041 is trying to lock:
ffff88801d040618 (&n->list_lock){-.-.}-{3:3}, at: get_partial_node_bulk mm/slub.c:3831 [inline]
ffff88801d040618 (&n->list_lock){-.-.}-{3:3}, at: __refill_objects_node+0x104/0xab0 mm/slub.c:7279
other info that might help us debug this:
context-{2:2}
locks held by syz-executor177/6041: 1, last CPU#1:
 #0: ffffffff9090b438 (tomoyo_ss){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
 #0: ffffffff9090b438 (tomoyo_ss){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:305 [inline]
 #0: ffffffff9090b438 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_read_lock security/tomoyo/common.h:1112 [inline]
 #0: ffffffff9090b438 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_check_open_permission+0x169/0x3c0 security/tomoyo/file.c:772
stack backtrace:
CPU: 1 UID: 0 PID: 6041 Comm: syz-executor177 Tainted: G S                  syzkaller #0 PREEMPT(full) 
Tainted: [S]=CPU_OUT_OF_SPEC
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_lock_invalid_wait_context kernel/locking/lockdep.c:4874 [inline]
 check_wait_context kernel/locking/lockdep.c:4946 [inline]
 __lock_acquire+0xfcc/0x1f40 kernel/locking/lockdep.c:5238
 lock_acquire kernel/locking/lockdep.c:5942 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:155 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:181
 get_partial_node_bulk mm/slub.c:3831 [inline]
 __refill_objects_node+0x104/0xab0 mm/slub.c:7279
 refill_objects+0x58/0x410 mm/slub.c:7405
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __kmalloc_cache_noprof+0x4f4/0x6d0 mm/slub.c:5559
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 kvm_async_pf_task_wake arch/x86/kernel/kvm.c:224 [inline]
 __sysvec_kvm_asyncpf_interrupt+0x334/0x610 arch/x86/kernel/kvm.c:338
 instr_sysvec_kvm_asyncpf_interrupt arch/x86/kernel/kvm.c:327 [inline]
 sysvec_kvm_asyncpf_interrupt+0x9e/0xc0 arch/x86/kernel/kvm.c:327
 </IRQ>
 <TASK>
 asm_sysvec_kvm_asyncpf_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:753
RIP: 0010:memcmp+0x156/0x1d0 lib/string.c:665
Code: 0f 86 fb fe ff ff 48 89 d8 48 89 de 48 c1 e8 03 83 e6 07 42 0f b6 14 28 48 8d 43 07 48 89 c1 48 c1 e9 03 40 38 f2 40 0f 9e c6 <84> d2 42 0f b6 0c 29 0f 95 c2 40 84 d6 0f 84 45 ff ff ff be 08 00
RSP: 0018:ffffc90003ab7538 EFLAGS: 00000297
RAX: ffff8880220be413 RBX: ffff8880220be40c RCX: 1ffff11004417c82
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8880220be40c
RBP: ffffffff8c58a940 R08: 0000000000000001 R09: 0000000000000066
R10: 0000000000000066 R11: 0000000000000001 R12: 0000000000000012
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000000
 strstr+0x109/0x170 lib/string.c:743
 tomoyo_add_entry security/tomoyo/common.c:2157 [inline]
 tomoyo_supervisor+0xf47/0x1340 security/tomoyo/common.c:2238
 tomoyo_audit_path_log security/tomoyo/file.c:169 [inline]
 tomoyo_path_permission security/tomoyo/file.c:592 [inline]
 tomoyo_path_permission+0x270/0x3b0 security/tomoyo/file.c:577
 tomoyo_check_open_permission+0x37f/0x3c0 security/tomoyo/file.c:782
 tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334
 security_file_open+0xb5/0x1e0 security/security.c:2739
 do_dentry_open+0x588/0x14d0 fs/open.c:973
 vfs_open+0x82/0x3f0 fs/open.c:1101
 do_open fs/namei.c:4836 [inline]
 path_openat+0x1a23/0x2450 fs/namei.c:4999
 do_file_open+0x20e/0x430 fs/namei.c:5028
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f589f9da7be
Code: 08 0f 85 55 ec ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007f589affe098 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f589affe6c0 RCX: 00007f589f9da7be
RDX: 0000000000000002 RSI: 00007f589affe1a0 RDI: ffffffffffffff9c
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f589affe1a0
R13: 0000000000000001 R14: 00007ffef59973a0 R15: 00007ffef5997488
 </TASK>
----------------
Code disassembly (best guess):
   0:	0f 86 fb fe ff ff    	jbe    0xffffff01
   6:	48 89 d8             	mov    %rbx,%rax
   9:	48 89 de             	mov    %rbx,%rsi
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	83 e6 07             	and    $0x7,%esi
  13:	42 0f b6 14 28       	movzbl (%rax,%r13,1),%edx
  18:	48 8d 43 07          	lea    0x7(%rbx),%rax
  1c:	48 89 c1             	mov    %rax,%rcx
  1f:	48 c1 e9 03          	shr    $0x3,%rcx
  23:	40 38 f2             	cmp    %sil,%dl
  26:	40 0f 9e c6          	setle  %sil
* 2a:	84 d2                	test   %dl,%dl <-- trapping instruction
  2c:	42 0f b6 0c 29       	movzbl (%rcx,%r13,1),%ecx
  31:	0f 95 c2             	setne  %dl
  34:	40 84 d6             	test   %dl,%sil
  37:	0f 84 45 ff ff ff    	je     0xffffff82
  3d:	be                   	.byte 0xbe
  3e:	08 00                	or     %al,(%rax)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/19 20:18 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c03c1a14507d 3f2522c6 .config console log report C ci-qemu-upstream WARNING: locking bug in __refill_objects_node
2026/10/16 10:09 upstream 2f2f7eeef8b0 3f2522c6 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in __refill_objects_node
* Struck through repros no longer work on HEAD.