linux-kernel - Re: [syzbot] INFO: rcu detected stall in __hrtimer_run

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Date:   Sun, 31 Jul 2022 00:38:10 -0700
From:   syzbot <syzbot+de9526ade17c659d8336@...kaller.appspotmail.com>
To:     hdanton@...a.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] INFO: rcu detected stall in __hrtimer_run_queues

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in __hrtimer_run_queues

------------[ cut here ]------------
On CPU1 hrtimer mac80211_hwsim_beacon took more than 4 ticks
WARNING: CPU: 1 PID: 6080 at kernel/time/hrtimer.c:1523 __run_hrtimer kernel/time/hrtimer.c:1523 [inline]
WARNING: CPU: 1 PID: 6080 at kernel/time/hrtimer.c:1523 __hrtimer_run_queues+0xe30/0xff0 kernel/time/hrtimer.c:1587
Modules linked in:
CPU: 1 PID: 6080 Comm: syz-executor.3 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:1523 [inline]
RIP: 0010:__hrtimer_run_queues+0xe30/0xff0 kernel/time/hrtimer.c:1587
Code: fa 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e b7 01 00 00 41 8b 77 40 48 c7 c7 c0 97 4d 89 48 8b 54 24 08 e8 ca d0 56 07 <0f> 0b e9 6e f4 ff ff e8 d4 c1 52 00 e9 68 f6 ff ff 48 8b 7c 24 18
RSP: 0018:ffffc90000db0e50 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88801dcb0000 RSI: ffffffff815b73e5 RDI: fffff520001b61bc
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff815b05be R11: 0000000000000000 R12: ffff8880263bd878
R13: 0000000000000004 R14: ffff8880b9f26c80 R15: ffff8880b9f26a00
FS:  00007f0886014700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000056c000 CR3: 0000000023e2c000 CR4: 0000000000350ee0
Call Trace:
 <IRQ>
 hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1604
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu kernel/softirq.c:420 [inline]
 irq_exit_rcu+0x134/0x200 kernel/softirq.c:432
 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629
RIP: 0010:lock_acquire+0x1d2/0x720 kernel/locking/lockdep.c:5410
Code: 48 c7 c7 a0 a9 4b 89 48 83 c4 20 e8 88 b9 a1 07 b8 ff ff ff ff 65 0f c1 05 ab 2a a9 7e 83 f8 01 0f 85 da 03 00 00 ff 34 24 9d <48> b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00 00 00 00 48 c7
RSP: 0018:ffffc900020ffd28 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 1ffff9200041ffa7 RCX: 0000000000000001
RDX: 1ffff11003b96130 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8ee6683f
R10: fffffbfff1dccd07 R11: 0000000000000001 R12: 0000000000000000
R13: ffff8880185411c8 R14: 0000000000000000 R15: 0000000000000000
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:354 [inline]
 setfl fs/fcntl.c:79 [inline]
 do_fcntl+0x696/0x1070 fs/fcntl.c:347
 __do_sys_fcntl fs/fcntl.c:463 [inline]
 __se_sys_fcntl fs/fcntl.c:448 [inline]
 __x64_sys_fcntl+0x165/0x1e0 fs/fcntl.c:448
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x465d99
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:00007f0886014188 EFLAGS: 00000246 ORIG_RAX: 0000000000000048
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465d99
RDX: 0000000000042000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 00000000004bcf27 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffefcbe216f R14: 00007f0886014300 R15: 0000000000022000
----------------
Code disassembly (best guess):
   0:	48 c7 c7 a0 a9 4b 89 	mov    $0xffffffff894ba9a0,%rdi
   7:	48 83 c4 20          	add    $0x20,%rsp
   b:	e8 88 b9 a1 07       	callq  0x7a1b998
  10:	b8 ff ff ff ff       	mov    $0xffffffff,%eax
  15:	65 0f c1 05 ab 2a a9 	xadd   %eax,%gs:0x7ea92aab(%rip)        # 0x7ea92ac8
  1c:	7e
  1d:	83 f8 01             	cmp    $0x1,%eax
  20:	0f 85 da 03 00 00    	jne    0x400
  26:	ff 34 24             	pushq  (%rsp)
  29:	9d                   	popfq
* 2a:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax <-- trapping instruction
  31:	fc ff df
  34:	48 01 c3             	add    %rax,%rbx
  37:	48 c7 03 00 00 00 00 	movq   $0x0,(%rbx)
  3e:	48                   	rex.W
  3f:	c7                   	.byte 0xc7


Tested on:

commit:         f40ddce8 Linux 5.11
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1791dcfe080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3565439810a4d2e5
dashboard link: https://syzkaller.appspot.com/bug?extid=de9526ade17c659d8336
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=157e1b36080000