Message-Id: <20241104193345.94e0d057a6b16dfb9d83a3fc@linux-foundation.org>
Date: Mon, 4 Nov 2024 19:33:45 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: syzbot <syzbot+56dc65adbd1d2ae1f844@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 syzkaller-bugs@...glegroups.com, Boqun Feng <boqun.feng@...il.com>, Peter
 Zijlstra <peterz@...radead.org>
Subject: Re: [syzbot] [mm?] WARNING: locking bug in __set_page_owner

On Sun, 03 Nov 2024 08:49:26 -0800 syzbot <syzbot+56dc65adbd1d2ae1f844@...kaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:

Help.  I don't understand this lockdep report. 
add_stack_record_to_list() is taking spin_lock_irqsave(stack_list_lock)
from within softirq. all seems well?

> HEAD commit:    f9f24ca362a4 Add linux-next specific files for 20241031
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=11ac6630580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=328572ed4d152be9
> dashboard link: https://syzkaller.appspot.com/bug?extid=56dc65adbd1d2ae1f844
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=171232a7980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/eb84549dd6b3/disk-f9f24ca3.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/beb29bdfa297/vmlinux-f9f24ca3.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/8881fe3245ad/bzImage-f9f24ca3.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+56dc65adbd1d2ae1f844@...kaller.appspotmail.com
> 
> =============================
> [ BUG: Invalid wait context ]
> 6.12.0-rc5-next-20241031-syzkaller #0 Not tainted
> -----------------------------
> syz.1.44/6083 is trying to lock:
> ffffffff8ea733d8 (stack_list_lock){-.-.}-{3:3}, at: add_stack_record_to_list mm/page_owner.c:182 [inline]
> ffffffff8ea733d8 (stack_list_lock){-.-.}-{3:3}, at: inc_stack_record_count mm/page_owner.c:214 [inline]
> ffffffff8ea733d8 (stack_list_lock){-.-.}-{3:3}, at: __set_page_owner+0x5cb/0x800 mm/page_owner.c:329
> other info that might help us debug this:
> context-{2:2}
> 1 lock held by syz.1.44/6083:
>  #0: ffff8880240995e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:129 [inline]
>  #0: ffff8880240995e0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x2da/0xcb0 mm/mmap.c:1701
> stack backtrace:
> CPU: 1 UID: 0 PID: 6083 Comm: syz.1.44 Not tainted 6.12.0-rc5-next-20241031-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> Call Trace:
>  <IRQ>
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
>  print_lock_invalid_wait_context kernel/locking/lockdep.c:4826 [inline]
>  check_wait_context kernel/locking/lockdep.c:4898 [inline]
>  __lock_acquire+0x15a8/0x2100 kernel/locking/lockdep.c:5176
>  lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
>  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>  _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
>  add_stack_record_to_list mm/page_owner.c:182 [inline]
>  inc_stack_record_count mm/page_owner.c:214 [inline]
>  __set_page_owner+0x5cb/0x800 mm/page_owner.c:329
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1541
>  prep_new_page mm/page_alloc.c:1549 [inline]
>  get_page_from_freelist+0x3725/0x3870 mm/page_alloc.c:3495
>  __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4771
>  alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
>  stack_depot_save_flags+0x666/0x830 lib/stackdepot.c:627
>  kasan_save_stack+0x4f/0x60 mm/kasan/common.c:48
>  __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:544
>  task_work_add+0xd9/0x490 kernel/task_work.c:77
>  __run_posix_cpu_timers kernel/time/posix-cpu-timers.c:1219 [inline]
>  run_posix_cpu_timers+0x6ac/0x810 kernel/time/posix-cpu-timers.c:1418
>  tick_sched_handle kernel/time/tick-sched.c:276 [inline]
>  tick_nohz_handler+0x37c/0x500 kernel/time/tick-sched.c:297
>  __run_hrtimer kernel/time/hrtimer.c:1691 [inline]
>  __hrtimer_run_queues+0x551/0xd50 kernel/time/hrtimer.c:1755
>  hrtimer_interrupt+0x396/0x990 kernel/time/hrtimer.c:1817
>  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
>  __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055
>  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
>  sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1049
>  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
> RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:321 [inline]
> RIP: 0010:handle_softirqs+0x1e3/0x980 kernel/softirq.c:542
> Code: 7c 24 70 45 0f b7 e4 48 c7 c7 20 c5 09 8c e8 c4 6c 6c 0a 65 66 c7 05 32 53 ac 7e 00 00 e8 05 67 45 00 fb 49 c7 c6 c0 a0 60 8e <b8> ff ff ff ff 41 0f bc c4 41 89 c7 41 ff c7 0f 84 eb 03 00 00 44
> RSP: 0018:ffffc90000a18e40 EFLAGS: 00000286
> RAX: b8b036f9cad4b600 RBX: ffffc90000a18ee0 RCX: ffffffff8170c69a
> RDX: dffffc0000000000 RSI: ffffffff8c0ad3a0 RDI: ffffffff8c604dc0
> RBP: ffffc90000a18f50 R08: ffffffff942cd877 R09: 1ffffffff2859b0e
> R10: dffffc0000000000 R11: fffffbfff2859b0f R12: 0000000000000010
> R13: 0000000000000000 R14: ffffffff8e60a0c0 R15: 1ffff11004bb4780
>  __do_softirq kernel/softirq.c:588 [inline]
>  invoke_softirq kernel/softirq.c:428 [inline]
>  __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
>  irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
>  common_interrupt+0xb9/0xd0 arch/x86/kernel/irq.c:278
>  </IRQ>
>  <TASK>
>  asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
> RIP: 0010:lock_is_held_type+0x13b/0x190
> Code: 75 44 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 4c 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 42 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
> RSP: 0018:ffffc9000307f618 EFLAGS: 00000206
> RAX: b8b036f9cad4b600 RBX: 0000000000000001 RCX: ffff888025da3c00
> RDX: ffff888025da3c00 RSI: ffffffff8c0ae580 RDI: ffffffff8c604dc0
> RBP: 0000000000000000 R08: ffffffff81e2d437 R09: ffffffff8bb86877
> R10: 0000000000000004 R11: ffff888025da3c00 R12: 0000000000000246
> R13: ffff888025da3c00 R14: 0000000000000000 R15: ffff8880240995e0
>  rwsem_assert_held_write include/linux/rwsem.h:203 [inline]
>  mmap_assert_write_locked include/linux/mmap_lock.h:70 [inline]
>  __is_vma_write_locked include/linux/mm.h:747 [inline]
>  vma_start_write include/linux/mm.h:766 [inline]
>  free_pgtables+0x433/0x840 mm/memory.c:406
>  exit_mmap+0x4cd/0xcb0 mm/mmap.c:1704
>  __mmput+0x115/0x390 kernel/fork.c:1344
>  exit_mm+0x220/0x310 kernel/exit.c:570
>  do_exit+0x9b2/0x28e0 kernel/exit.c:925
>  do_group_exit+0x207/0x2c0 kernel/exit.c:1087
>  get_signal+0x16a3/0x1740 kernel/signal.c:2884
>  arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
>  exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
>  exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
>  syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
>  do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f3e8657e719
> Code: Unable to access opcode bytes at 0x7f3e8657e6ef.
> RSP: 002b:00007f3e872b30e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: 0000000000000001 RBX: 00007f3e86735f88 RCX: 00007f3e8657e719
> RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f3e86735f8c
> RBP: 00007f3e86735f80 R08: 7fffffffffffffff R09: 0000000000000000
> R10: 000000000000003c R11: 0000000000000246 R12: 00007f3e86735f8c
> R13: 0000000000000000 R14: 00007fff211a29e0 R15: 00007fff211a2ac8
>  </TASK>
> ----------------
> Code disassembly (best guess):
>    0:	7c 24                	jl     0x26
>    2:	70 45                	jo     0x49
>    4:	0f b7 e4             	movzwl %sp,%esp
>    7:	48 c7 c7 20 c5 09 8c 	mov    $0xffffffff8c09c520,%rdi
>    e:	e8 c4 6c 6c 0a       	call   0xa6c6cd7
>   13:	65 66 c7 05 32 53 ac 	movw   $0x0,%gs:0x7eac5332(%rip)        # 0x7eac534f
>   1a:	7e 00 00
>   1d:	e8 05 67 45 00       	call   0x456727
>   22:	fb                   	sti
>   23:	49 c7 c6 c0 a0 60 8e 	mov    $0xffffffff8e60a0c0,%r14
> * 2a:	b8 ff ff ff ff       	mov    $0xffffffff,%eax <-- trapping instruction
>   2f:	41 0f bc c4          	bsf    %r12d,%eax
>   33:	41 89 c7             	mov    %eax,%r15d
>   36:	41 ff c7             	inc    %r15d
>   39:	0f 84 eb 03 00 00    	je     0x42a
>   3f:	44                   	rex.R
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup

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