[syzbot] [kvm?] WARNING: locking bug in __refill_objects_node

[syzbot] [kvm?] WARNING: locking bug in __refill_objects_node

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c03c1a14507d Linux 7.3
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=128d8ca5580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=129d675874dbf896
dashboard link: https://syzkaller.appspot.com/bug?extid=f11512d1e5878ba5e60e
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=168d8ca5580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f11512d1e5878ba5e60e@syzkaller.appspotmail.com

=============================
[ 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)


---
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Re: [syzbot] [kvm?] WARNING: locking bug in __refill_objects_node

[Hillf Danton]

Ask the locking people to shed light on the warning.

> Date: Mon, 26 Oct 2026 03:19:37 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c03c1a14507d Linux 7.3
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> console output: https://syzkaller.appspot.com/x/log.txt?x=128d8ca5580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=129d675874dbf896
> dashboard link: https://syzkaller.appspot.com/bug?extid=f11512d1e5878ba5e60e
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=168d8ca5580000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f11512d1e5878ba5e60e@syzkaller.appspotmail.com
> 
> =============================
> [ 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