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Date: Tue, 02 Apr 2024 11:05:31 -0700
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Subject: [syzbot] [kernel?] WARNING: suspicious RCU usage in __do_softirq
From: syzbot <syzbot+dce04ed6d1438ad69656@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, peterz@infradead.org, 
	syzkaller-bugs@googlegroups.com, tglx@linutronix.de
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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
 __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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