syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=8893, q=74 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294956386-4294945885), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g8893 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27656 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5783 Comm: syz-executor373 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:127 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:178 [inline]
RIP: 0010:kasan_check_range+0x89/0x290 mm/kasan/generic.c:187
Code: 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 3d 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb 41 80 3b 00 <0f> 85 8d 01 00 00 49 ff c3 48 ff c3 75 ee e9 1d 01 00 00 44 89 dd
RSP: 0018:ffffc900047af4c8 EFLAGS: 00000046
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: ffffffff816842a7
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff911c4530
RBP: ffffc900047af748 R08: ffffffff911c4537 R09: 1ffffffff22388a6
R10: dffffc0000000000 R11: fffffbfff22388a6 R12: 0000000000000001
R13: ffff888028310000 R14: fffffbfff22388a7 R15: 1ffffffff22388a6
FS:  00007f366f0fb6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 0000000075036000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 lookup_chain_cache_add kernel/locking/lockdep.c:3781 [inline]
 validate_chain kernel/locking/lockdep.c:3837 [inline]
 __lock_acquire+0x1347/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __might_fault+0xc6/0x120 mm/memory.c:5968
 __copy_to_user include/linux/uaccess.h:133 [inline]
 save_xstate_epilog arch/x86/kernel/fpu/signal.c:127 [inline]
 copy_fpstate_to_sigframe+0xa00/0xc60 arch/x86/kernel/fpu/signal.c:245
 get_sigframe+0x5e2/0x7d0 arch/x86/kernel/signal.c:142
 x64_setup_rt_frame+0x15e/0xc40 arch/x86/kernel/signal_64.c:175
 setup_rt_frame arch/x86/kernel/signal.c:223 [inline]
 handle_signal arch/x86/kernel/signal.c:267 [inline]
 arch_do_signal_or_restart+0x42c/0x800 arch/x86/kernel/signal.c:312
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f366f123b97
Code: 00 85 c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 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 d0 ff ff ff f7 d8 64 89
RSP: 002b:00007f366f0fb178 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f366f1cdb48 RCX: 00007f366f123b99
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f366f1cdb48
RBP: 00007f366f1cdb40 R08: 00007f366f0fbcdc R09: 00007f366f0fbcdc
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f366f1cdb4c
R13: 0000000000000000 R14: 00007ffff8f1cba0 R15: 00007ffff8f1cc88
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.289 msecs