[v5.15] INFO: rcu detected stall in rt_sigreturn

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aff03380bda4 Linux 5.15.131
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1074aac7a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=6587a45fd4ed4bea
dashboard link: https://syzkaller.appspot.com/bug?extid=0ca35102d68b60f5d4a0
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=10756180680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16505ac7a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/27b8e091695d/disk-aff03380.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/966318f77343/vmlinux-aff03380.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5eb45b408cbc/bzImage-aff03380.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ca351...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 0, t=10502 jiffies, g=3593, q=9)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294973738-4294963236), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g3593 f0x2 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:25888 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5026 [inline]
__schedule+0x12c4/0x4590 kernel/sched/core.c:6372
schedule+0x11b/0x1f0 kernel/sched/core.c:6455
schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1884
rcu_gp_fqs_loop+0x2af/0xf70 kernel/rcu/tree.c:1959
rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2132
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 3558 Comm: syz-executor296 Not tainted 5.15.131-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:481
print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:586
check_cpu_stall kernel/rcu/tree_stall.h:729 [inline]
rcu_pending kernel/rcu/tree.c:3911 [inline]
rcu_sched_clock_irq+0x94f/0x1770 kernel/rcu/tree.c:2606
update_process_times+0x196/0x200 kernel/time/timer.c:1788
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
__sysvec_apic_timer_interrupt+0x139/0x470 arch/x86/kernel/apic/apic.c:1102
sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1096
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:217 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x4/0x80 kernel/kcov.c:284
Code: 89 f8 89 f6 48 c7 44 0a 08 03 00 00 00 48 89 44 0a 10 48 89 74 0a 18 4c 89 44 0a 20 49 ff c1 4c 89 09 c3 0f 1f 00 4c 8b 04 24 <65> 48 8b 15 f4 4e 82 7e 65 8b 05 f5 4e 82 7e a9 00 01 ff 00 74 10
RSP: 0018:ffffc90002e1fd28 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000080000000 RCX: ffff88807a489dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e1fe50 R08: ffffffff8406d0f4 R09: fffffbfff1bc8146
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000018
R13: dffffc0000000000 R14: ffffc90002e1fdc0 R15: 00007ffe46de3790
_copy_from_user+0x54/0x170 lib/usercopy.c:15
copy_from_user include/linux/uaccess.h:192 [inline]
restore_altstack+0x9a/0x400 kernel/signal.c:4241
__do_sys_rt_sigreturn+0x19d/0x250 arch/x86/kernel/signal.c:677
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f6ea8fd3e79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe46de3d28 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f6ea8fd3e79
RDX: 000000002006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000555557210370
R13: 0000000000000005 R14: 00007ffe46de3da0 R15: 00007ffe46de3d90
</TASK>


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