syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P21178/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=148109, q=162 ncpus=2)
task:syz.0.2954      state:R  running task     stack:25640 pid:21178 ppid:12507  flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__kasan_check_read+0x4/0x20 mm/kasan/shadow.c:31
Code: 41 5e 41 5f 5d c3 48 c7 c7 7e 1c 79 8c 4c 89 e6 eb 0a 48 c7 c7 3b 76 61 8c 48 89 de e8 35 27 85 08 31 ed eb d4 cc f3 0f 1e fa <89> f6 48 8b 0c 24 31 d2 e9 df ea ff ff 66 2e 0f 1f 84 00 00 00 00
RSP: 0018:ffffc900046af778 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e4a8828
RBP: ffffc900046af898 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc900046afa4c R11: fffff520008d5f52 R12: 1ffff920008d5efc
R13: ffffffff8cd2fbe0 R14: 0000000000000001 R15: dffffc0000000000
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:504 [inline]
 cpu_online include/linux/cpumask.h:1082 [inline]
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0xbc/0x410 kernel/locking/lockdep.c:5725
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 __pte_offset_map+0x48/0x2c0 mm/pgtable-generic.c:287
 pte_offset_map_nolock+0x44/0x130 mm/pgtable-generic.c:314
 handle_pte_fault mm/memory.c:5011 [inline]
 __handle_mm_fault mm/memory.c:5166 [inline]
 handle_mm_fault+0xe1b/0x4920 mm/memory.c:5331
 faultin_page mm/gup.c:868 [inline]
 __get_user_pages+0x5ea/0x1470 mm/gup.c:1167
 populate_vma_page_range+0x2b6/0x370 mm/gup.c:1593
 __mm_populate+0x24c/0x380 mm/gup.c:1696
 mm_populate include/linux/mm.h:3317 [inline]
 vm_mmap_pgoff+0x2e7/0x400 mm/util.c:561
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe74bf8ebe9
RSP: 002b:00007fe74ce83038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fe74c1b5fa0 RCX: 00007fe74bf8ebe9
RDX: b635773f06ebbeef RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fe74c011e19 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe74c1b6038 R14: 00007fe74c1b5fa0 R15: 00007fffe4b0a548
 </TASK>
rcu: rcu_preempt kthread starved for 10408 jiffies! g148109 f0x0 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:27080 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 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: 0 Comm: swapper/1 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 e6 3a 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6
RAX: fc7f862d8c648300 RBX: ffffffff8161914b RCX: fc7f862d8c648300
RDX: 0000000000000001 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0
RBP: ffffc90000187f20 R08: ffff8880b8f36d4b R09: 1ffff110171e6da9
R10: dffffc0000000000 R11: ffffed10171e6daa R12: ffffffff8e4a8828
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110037cb780
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3478b4ff98 CR3: 000000002d69d000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>