syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=8b74/1/0x4000000000000000 softirq=63761/63762 fqs=21
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6929/1:b..l
rcu: 	(detected by 0, t=10506 jiffies, g=61193, q=285 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 14270 Comm: syz.1.2227 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_preemption_disabled+0x2/0xe0 lib/smp_processor_id.c:13
Code: 0f 65 8b 05 9c 75 3a 08 85 c0 74 04 90 0f 0b 90 e9 53 fc ff ff 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 54 <55> 53 48 83 ec 08 65 8b 1d d5 31 3a 08 65 8b 05 ca 31 3a 08 a9 ff
RSP: 0018:ffffc90000a08e18 EFLAGS: 00000086
RAX: 0000000080010002 RBX: ffff8880b8528540 RCX: ffffffff81aadd8f
RDX: ffff88802f0b24c0 RSI: ffffffff8bf2b500 RDI: ffffffff8bf2b540
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88802f0b2ff0 R12: ffff8880b8528440
R13: 0000000000000001 R14: ffff888059cb7300 R15: ffffffff898111e0
FS:  00007f4de6a0b6c0(0000) GS:ffff8881249f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 0000000049fa0000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
 rcu_is_watching+0x12/0xc0 kernel/rcu/tree.c:751
 trace_hrtimer_expire_entry include/trace/events/timer.h:259 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1774 [inline]
 __hrtimer_run_queues+0x9f4/0xc40 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:kasan_check_range+0x10/0x1b0 mm/kasan/generic.c:199
Code: 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 85 f6 0f 84 64 01 00 00 48 89 f8 <41> 54 44 0f b6 c2 48 01 f0 55 53 0f 82 d7 00 00 00 eb 0f cc cc cc
RSP: 0018:ffffc9000d2ff550 EFLAGS: 00000202
RAX: ffffea0000cee970 RBX: 0000000000000005 RCX: ffffffff821a93cb
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffea0000cee970
RBP: ffffea0000cee940 R08: 0000000000000000 R09: fffff9400019dd26
R10: ffffea0000cee937 R11: 0000000000000003 R12: ffffea0000cee940
R13: ffffea0000cee934 R14: dffffc0000000000 R15: ffffea0000cee970
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
 page_expected_state mm/page_alloc.c:1075 [inline]
 check_new_page mm/page_alloc.c:1784 [inline]
 check_new_pages mm/page_alloc.c:1798 [inline]
 __rmqueue_pcplist+0x31b/0x15f0 mm/page_alloc.c:3344
 rmqueue_pcplist mm/page_alloc.c:3371 [inline]
 rmqueue mm/page_alloc.c:3401 [inline]
 get_page_from_freelist+0x15d3/0x31a0 mm/page_alloc.c:3942
 __alloc_frozen_pages_noprof+0x25f/0x2430 mm/page_alloc.c:5240
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x2c3/0x430 mm/slub.c:3302
 ___slab_alloc+0xe18/0x1c90 mm/slub.c:4656
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __kmalloc_cache_noprof+0x485/0x800 mm/slub.c:5771
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 alloc_super+0x52/0xd00 fs/super.c:319
 sget_fc+0x116/0xc20 fs/super.c:761
 vfs_get_super fs/super.c:1319 [inline]
 get_tree_nodev+0x28/0x190 fs/super.c:1343
 vfs_get_tree+0x8e/0x330 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount fs/namespace.c:3712 [inline]
 path_mount+0x7bf/0x23a0 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount fs/namespace.c:4201 [inline]
 __x64_sys_mount+0x293/0x310 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4de5b8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4de6a0b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4de5de5fa0 RCX: 00007f4de5b8f749
RDX: 0000200000000080 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007f4de5c13f91 R08: 0000200000000400 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4de5de6038 R14: 00007f4de5de5fa0 R15: 00007ffc0b680218
 </TASK>
task:syz-executor    state:R  running task     stack:23336 pid:6929  tgid:6929  ppid:6926   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:422 [inline]
RIP: 0010:unwind_next_frame+0x15f2/0x20b0 arch/x86/kernel/unwind_orc.c:668
Code: bf 69 02 ba 08 00 00 00 4c 89 ef 4d 8d 7d 34 4c 01 f5 48 89 ee e8 0e e8 ff ff 84 c0 0f 84 98 ed ff ff 48 89 ef e8 ee df ff ff <4c> 89 e2 48 89 c5 48 c1 ea 03 48 b8 00 00 00 00 00 fc ff df 80 3c
RSP: 0018:ffffc9001be178e8 EFLAGS: 00000202
RAX: 0000000000000002 RBX: 0000000000000001 RCX: ffffc9001be18000
RDX: ffffc9001be17d01 RSI: ffffc9001be17d40 RDI: ffffc9001be17d40
RBP: ffffc9001be17d40 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000002 R11: 0000000000011d3b R12: ffffc9001be17998
R13: ffffc9001be17958 R14: ffffc9001be17d40 R15: ffffc9001be1798c
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x25e/0x770 mm/slub.c:5270
 alloc_empty_file+0x55/0x1e0 fs/file_table.c:237
 alloc_file fs/file_table.c:354 [inline]
 alloc_file_pseudo+0x13a/0x230 fs/file_table.c:383
 sock_alloc_file+0x50/0x210 net/socket.c:483
 sock_map_fd net/socket.c:513 [inline]
 __sys_socket+0x1c0/0x260 net/socket.c:1756
 __do_sys_socket net/socket.c:1761 [inline]
 __se_sys_socket net/socket.c:1759 [inline]
 __x64_sys_socket+0x72/0xb0 net/socket.c:1759
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3f12b91667
RSP: 002b:00007fff3a90f8d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f3f12b91667
RDX: 0000000000000006 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 00007fff3a90ffcc R08: 00007fff3a90f8cc R09: 00007fff3a90fcd7
R10: 00007fff3a90f950 R11: 0000000000000202 R12: 000000000000018b
R13: 00000000000927c0 R14: 00000000000ba76f R15: 00007fff3a910020
 </TASK>
rcu: rcu_preempt kthread starved for 10400 jiffies! g61193 f0x0 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:28120 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 46 5f 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 13 b9 11 00 fb f4 <e9> cc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 000002c6
RAX: 0000000002e895ed RBX: 0000000000000000 RCX: ffffffff8b78a6d9
RDX: 0000000000000000 RSI: ffffffff8dacf6aa RDI: ffffffff8bf2b580
RBP: fffffbfff1c12f68 R08: 0000000000000001 R09: ffffed101708673d
R10: ffff8880b84339eb R11: ffffffff8e098670 R12: 0000000000000000
R13: ffffffff8e097b40 R14: ffffffff9088cdd0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881248f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff738193838 CR3: 00000000752e6000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000001800
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x38d/0x510 kernel/sched/idle.c:332
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:430
 rest_init+0x16b/0x2b0 init/main.c:757
 start_kernel+0x3ef/0x4d0 init/main.c:1206
 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x148
 </TASK>