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From: Z qiang <qiang.zhang1211@gmail.com>
Date: Tue, 16 Apr 2024 16:10:17 +0800
Message-ID: <CALm+0cWx1kYtftE4nj7Jjgx2_bmNmSrBAgd36ksSvxJtNVhxHg@mail.gmail.com>
Subject: Re: [syzbot] [kernel?] WARNING: suspicious RCU usage in __do_softirq
To: syzbot <syzbot+dce04ed6d1438ad69656@syzkaller.appspotmail.com>, 
	"Paul E. McKenney" <paulmck@kernel.org>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, 
	syzkaller-bugs@googlegroups.com, tglx@linutronix.de
Content-Type: text/plain; charset="UTF-8"

Cc: Paul
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    c0b832517f62 Add linux-next specific files for 20240402
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=15f64776180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=afcaf46d374cec8c
> dashboard link: https://syzkaller.appspot.com/bug?extid=dce04ed6d1438ad69656
> 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=10f00471180000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/0d36ec76edc7/disk-c0b83251.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6f9bb4e37dd0/vmlinux-c0b83251.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2349287b14b7/bzImage-c0b83251.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+dce04ed6d1438ad69656@syzkaller.appspotmail.com
>
> =============================
> WARNING: suspicious RCU usage
> 6.9.0-rc2-next-20240402-syzkaller #0 Not tainted
> -----------------------------
> kernel/rcu/tree.c:276 Illegal rcu_softirq_qs() in RCU read-side critical section!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by ksoftirqd/0/16:
>  #0: ffffffff8e334d20 (rcu_read_lock_sched){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
>  #0: ffffffff8e334d20 (rcu_read_lock_sched){....}-{1:2}, at: rcu_read_lock_sched include/linux/rcupdate.h:933 [inline]
>  #0: ffffffff8e334d20 (rcu_read_lock_sched){....}-{1:2}, at: pfn_valid include/linux/mmzone.h:2019 [inline]
>  #0: ffffffff8e334d20 (rcu_read_lock_sched){....}-{1:2}, at: __virt_addr_valid+0x183/0x520 arch/x86/mm/physaddr.c:65
>
> stack backtrace:
> CPU: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
>  <IRQ>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  lockdep_rcu_suspicious+0x221/0x340 kernel/locking/lockdep.c:6712
>  rcu_softirq_qs+0xd9/0x370 kernel/rcu/tree.c:273
>  __do_softirq+0x5fd/0x980 kernel/softirq.c:568
>  invoke_softirq kernel/softirq.c:428 [inline]
>  __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
>  irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
>  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
>  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
>  </IRQ>
>  <TASK>
>  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
> RIP: 0010:debug_lockdep_rcu_enabled+0xd/0x40 kernel/rcu/update.c:320
> Code: f5 90 0f 0b 90 90 90 eb c6 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 31 c0 83 3d c7 0f 28 04 00 <74> 1e 83 3d 26 42 28 04 00 74 15 65 48 8b 0c 25 c0 d3 03 00 31 c0
> RSP: 0018:ffffc90000157a50 EFLAGS: 00000202
> RAX: 0000000000000000 RBX: 00000000000000a0 RCX: 0000000000000001
> RDX: dffffc0000000000 RSI: ffffffff8bcae740 RDI: ffffffff8c1f7ec0
> RBP: dffffc0000000000 R08: ffffffff92f3a527 R09: 1ffffffff25e74a4
> R10: dffffc0000000000 R11: fffffbfff25e74a5 R12: 0000000029373578
> R13: 1ffff9200002af64 R14: ffffffff814220f3 R15: ffff88813fff90a0
>  rcu_read_lock_sched include/linux/rcupdate.h:934 [inline]
>  pfn_valid include/linux/mmzone.h:2019 [inline]
>  __virt_addr_valid+0x1a9/0x520 arch/x86/mm/physaddr.c:65
>  kasan_addr_to_slab+0xd/0x80 mm/kasan/common.c:37
>  __kasan_record_aux_stack+0x11/0xc0 mm/kasan/generic.c:526


This should be caused by the following commit:
d818cc76e2b4 ("kasan: Record work creation stack trace with interrupts enabled")

Is it possible to make the rcu_softirq_qs() run only in ksoftirqd task?

Thanks
Zqiang

>  __call_rcu_common kernel/rcu/tree.c:3096 [inline]
>  call_rcu+0x167/0xa70 kernel/rcu/tree.c:3200
>  context_switch kernel/sched/core.c:5412 [inline]
>  __schedule+0x17f0/0x4a50 kernel/sched/core.c:6746
>  __schedule_loop kernel/sched/core.c:6823 [inline]
>  schedule+0x14b/0x320 kernel/sched/core.c:6838
>  smpboot_thread_fn+0x61e/0xa30 kernel/smpboot.c:160
>  kthread+0x2f0/0x390 kernel/kthread.c:388
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
>  </TASK>
> ----------------
> Code disassembly (best guess):
>    0:   f5                      cmc
>    1:   90                      nop
>    2:   0f 0b                   ud2
>    4:   90                      nop
>    5:   90                      nop
>    6:   90                      nop
>    7:   eb c6                   jmp    0xffffffcf
>    9:   0f 1f 40 00             nopl   0x0(%rax)
>    d:   90                      nop
>    e:   90                      nop
>    f:   90                      nop
>   10:   90                      nop
>   11:   90                      nop
>   12:   90                      nop
>   13:   90                      nop
>   14:   90                      nop
>   15:   90                      nop
>   16:   90                      nop
>   17:   90                      nop
>   18:   90                      nop
>   19:   90                      nop
>   1a:   90                      nop
>   1b:   90                      nop
>   1c:   90                      nop
>   1d:   f3 0f 1e fa             endbr64
>   21:   31 c0                   xor    %eax,%eax
>   23:   83 3d c7 0f 28 04 00    cmpl   $0x0,0x4280fc7(%rip)        # 0x4280ff1
> * 2a:   74 1e                   je     0x4a <-- trapping instruction
>   2c:   83 3d 26 42 28 04 00    cmpl   $0x0,0x4284226(%rip)        # 0x4284259
>   33:   74 15                   je     0x4a
>   35:   65 48 8b 0c 25 c0 d3    mov    %gs:0x3d3c0,%rcx
>   3c:   03 00
>   3e:   31 c0                   xor    %eax,%eax
>
>
> ---
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>
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