syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=10502 jiffies, g=9229, q=73 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294955551-4294945049), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g9229 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:
CPU: 1 PID: 5806 Comm: syz-executor323 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:lock_release+0x594/0x8c0 kernel/locking/lockdep.c:5778
Code: 00 00 00 f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 2f 04 f8 75 70 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 43 c7 44 2f 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900048b7a00 EFLAGS: 00000206
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: 704414460e9ce500
RDX: 0000000000000000 RSI: ffffffff8acadb60 RDI: ffffffff8b1c8fa0
RBP: ffffc900048b7b10 R08: ffffffff8e8b19af R09: 1ffffffff1d16335
R10: dffffc0000000000 R11: fffffbfff1d16336 R12: ffff888078b864e0
R13: dffffc0000000000 R14: ffff888078b864d0 R15: 1ffff92000916f4c
FS:  0000555564cd93c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 00000000310c0000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 __copy_from_user include/linux/uaccess.h:97 [inline]
 check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
 __fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
 fpu__restore_sig+0x20b/0x11c0 arch/x86/kernel/fpu/signal.c:493
 restore_sigcontext arch/x86/kernel/signal_64.c:95 [inline]
 __ia32_sys_rt_sigreturn+0x6e2/0x860 arch/x86/kernel/signal_64.c:266
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f01bb8886c9
Code: 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 01 48
RSP: 002b:00007ffc29eb5af8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f01bb8886c9
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007f01bb860990 R09: 00007f01bb860990
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f01bb8ff075
R13: 00007f01bb8fd1bd R14: 00007ffc29eb5b30 R15: 0000000000000000
 </TASK>