[syzbot] INFO: rcu detected stall in syscall_exit_to_user_mode

[syzbot <syzbot+0e964fad69a9c462bc1e@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d5ae8d7f85b7 Revert "media: dvb header files: move some he..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1138c9ad300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=765eea9a273a8879
dashboard link: https://syzkaller.appspot.com/bug?extid=0e964fad69a9c462bc1e
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e964fad69a9c462bc1e@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=70e/1/0x4000000000000000 softirq=60586/60587 fqs=2492 
	(t=10501 jiffies g=90689 q=3510)
rcu: rcu_preempt kthread starved for 5495 jiffies! g90689 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:28864 pid:   14 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:4681 [inline]
 __schedule+0x93a/0x26f0 kernel/sched/core.c:5938
 schedule+0xd3/0x270 kernel/sched/core.c:6017
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline]
 rcu_gp_kthread+0xd34/0x1980 kernel/rcu/tree.c:2169
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10491 Comm: syz-executor.3 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unwind_next_frame+0x829/0x1ce0 arch/x86/kernel/unwind_orc.c:466
Code: 83 e0 07 40 38 c6 40 0f 9e c7 40 84 f6 0f 95 c0 40 84 c7 0f 85 bc 0f 00 00 49 0f bf 30 48 01 d6 48 89 74 24 60 e9 d8 fd ff ff <48> b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 48 c1 ea 03 80 3c 02
RSP: 0018:ffffc90000007698 EFLAGS: 00000297
RAX: 0000000000000005 RBX: 1ffff92000000edb RCX: ffffffff8e5a56dd
RDX: 0000000000000005 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000002 R08: ffffffff8e5a56d8 R09: ffffffff8e5a56a8
R10: fffff52000000ef9 R11: 0000000000086088 R12: ffffc900000077b8
R13: ffffc900000077a5 R14: ffffc90000007770 R15: ffffffff8e5a56dc
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c01b7ba1b0 CR3: 0000000014fb2000 CR4: 00000000001526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 arch_stack_walk+0x7d/0xe0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:121
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x83/0xb0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:2959 [inline]
 kmem_cache_alloc_node+0x266/0x3e0 mm/slub.c:2995
 __alloc_skb+0x20b/0x340 net/core/skbuff.c:414
 skb_copy+0x137/0x2f0 net/core/skbuff.c:1581
 mac80211_hwsim_tx_frame_no_nl.isra.0+0xb17/0x1330 drivers/net/wireless/mac80211_hwsim.c:1565
 mac80211_hwsim_tx_frame+0x1ee/0x2a0 drivers/net/wireless/mac80211_hwsim.c:1784
 mac80211_hwsim_beacon_tx+0x49b/0x930 drivers/net/wireless/mac80211_hwsim.c:1838
 __iterate_interfaces+0x1e5/0x520 net/mac80211/util.c:793
 ieee80211_iterate_active_interfaces_atomic+0x70/0x180 net/mac80211/util.c:829
 mac80211_hwsim_beacon+0xd5/0x1a0 drivers/net/wireless/mac80211_hwsim.c:1861
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1601
 hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1618
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__page_mapcount+0x2/0x350 mm/util.c:716
Code: 89 e7 e8 31 cf 17 00 e9 10 fe ff ff e8 27 cf 17 00 e9 74 fe ff ff e8 1d cf 17 00 e9 3c fe ff ff 0f 1f 84 00 00 00 00 00 41 56 <41> 55 41 54 55 48 89 fd 4c 8d 65 30 53 e8 ec 94 d1 ff be 04 00 00
RSP: 0018:ffffc900180177a0 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88807d149c40 RSI: ffffffff81aa23f5 RDI: ffffea0001deaa80
RBP: ffffea0001deaa80 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81aa28ae R11: 0000000000000000 R12: ffffea0001deaa88
R13: 0000000000000001 R14: dffffc0000000000 R15: 0000000000aab000
 page_mapcount include/linux/mm.h:875 [inline]
 zap_pte_range mm/memory.c:1363 [inline]
 zap_pmd_range mm/memory.c:1481 [inline]
 zap_pud_range mm/memory.c:1510 [inline]
 zap_p4d_range mm/memory.c:1531 [inline]
 unmap_page_range+0xf1d/0x2a10 mm/memory.c:1552
 unmap_single_vma+0x198/0x300 mm/memory.c:1597
 unmap_vmas+0x16d/0x2f0 mm/memory.c:1629
 exit_mmap+0x1d0/0x620 mm/mmap.c:3201
 __mmput+0x122/0x470 kernel/fork.c:1101
 mmput+0x58/0x60 kernel/fork.c:1122
 exit_mm kernel/exit.c:501 [inline]
 do_exit+0xae2/0x2a60 kernel/exit.c:812
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2808
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: Unable to access opcode bytes at RIP 0x4665bf.
RSP: 002b:00007f1283537218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056bf88 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056bf88
RBP: 000000000056bf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf8c
R13: 0000000000a9fb1f R14: 00007f1283537300 R15: 0000000000022000
NMI backtrace for cpu 1
CPU: 1 PID: 4075 Comm: syz-executor.4 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:342
 print_cpu_stall kernel/rcu/tree_stall.h:625 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:700 [inline]
 rcu_pending kernel/rcu/tree.c:3922 [inline]
 rcu_sched_clock_irq.cold+0x9f/0x747 kernel/rcu/tree.c:2641
 update_process_times+0x16d/0x200 kernel/time/timer.c:1785
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1601
 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x40/0xc0 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191
Code: 74 24 10 e8 9a fa 2d f8 48 89 ef e8 42 70 2e f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 <e8> 03 4e 22 f8 65 8b 05 ec c8 d4 76 85 c0 74 0a 5b 5d c3 e8 e0 aa
RSP: 0018:ffffc90000dc0c08 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000200 RCX: 1ffffffff1fa4e6a
RDX: 0000000000000000 RSI: 0000000000000102 RDI: 0000000000000001
RBP: ffff8880b9d40280 R08: 0000000000000001 R09: ffffffff8fcd59bf
R10: 0000000000000001 R11: 0000000000000000 R12: 000000010000c10b
R13: ffff8880b9d40280 R14: 0000000000000000 R15: 00000000ffffffff
 __mod_timer+0x837/0xe30 kernel/time/timer.c:1065
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:finish_task_switch.isra.0+0x23c/0xa50 kernel/sched/core.c:4555
Code: 8b 3a 4c 89 e7 48 c7 02 00 00 00 00 ff d1 4d 85 ff 75 bf 4c 89 e7 e8 23 3c dd 07 e8 fe e7 2b 00 fb 65 48 8b 1c 25 40 f0 01 00 <48> 8d bb 10 15 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1
RSP: 0018:ffffc90003ae7810 EFLAGS: 00000202
RAX: 00000000000003cd RBX: ffff888030a13880 RCX: 1ffffffff1f9c5a2
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003ae7850 R08: 0000000000000001 R09: ffffffff8fcd5907
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880b9d51b00
R13: ffff88801f1c1c40 R14: 0000000000000000 R15: ffff8880b9d51b18
 context_switch kernel/sched/core.c:4684 [inline]
 __schedule+0x942/0x26f0 kernel/sched/core.c:5938
 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6098
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 put_cpu_partial+0x1a1/0x230 mm/slub.c:2482
 qlink_free mm/kasan/quarantine.c:146 [inline]
 qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
 __kasan_slab_alloc+0x95/0xb0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:2959 [inline]
 slab_alloc mm/slub.c:2967 [inline]
 __kmalloc+0x1f4/0x330 mm/slub.c:4111
 kmalloc include/linux/slab.h:596 [inline]
 tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
 tomoyo_realpath_nofollow+0xc8/0xe0 security/tomoyo/realpath.c:309
 tomoyo_find_next_domain+0x280/0x1f80 security/tomoyo/domain.c:727
 tomoyo_bprm_check_security security/tomoyo/tomoyo.c:101 [inline]
 tomoyo_bprm_check_security+0x121/0x1a0 security/tomoyo/tomoyo.c:91
 security_bprm_check+0x45/0xa0 security/security.c:866
 search_binary_handler fs/exec.c:1709 [inline]
 exec_binprm fs/exec.c:1762 [inline]
 bprm_execve fs/exec.c:1831 [inline]
 bprm_execve+0x732/0x19b0 fs/exec.c:1793
 do_execveat_common+0x5e3/0x780 fs/exec.c:1920
 do_execve fs/exec.c:1988 [inline]
 __do_sys_execve fs/exec.c:2064 [inline]
 __se_sys_execve fs/exec.c:2059 [inline]
 __x64_sys_execve+0x8f/0xc0 fs/exec.c:2059
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc2fc6a3188 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 0000000000a9fb1f R14: 00007fc2fc6a3300 R15: 0000000000022000
----------------
Code disassembly (best guess):
   0:	83 e0 07             	and    $0x7,%eax
   3:	40 38 c6             	cmp    %al,%sil
   6:	40 0f 9e c7          	setle  %dil
   a:	40 84 f6             	test   %sil,%sil
   d:	0f 95 c0             	setne  %al
  10:	40 84 c7             	test   %al,%dil
  13:	0f 85 bc 0f 00 00    	jne    0xfd5
  19:	49 0f bf 30          	movswq (%r8),%rsi
  1d:	48 01 d6             	add    %rdx,%rsi
  20:	48 89 74 24 60       	mov    %rsi,0x60(%rsp)
  25:	e9 d8 fd ff ff       	jmpq   0xfffffe02
* 2a:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax <-- trapping instruction
  31:	fc ff df
  34:	48 8b 54 24 08       	mov    0x8(%rsp),%rdx
  39:	48 c1 ea 03          	shr    $0x3,%rdx
  3d:	80                   	.byte 0x80
  3e:	3c 02                	cmp    $0x2,%al


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