syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P14271/1:b..l P14263/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=72065, q=339 ncpus=2)
task:syz.5.1931      state:R  running task     stack:25336 pid:14263 tgid:14262 ppid:13838  task_flags:0x400040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7190
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:memset+0xf/0x20 arch/x86/lib/memset_64.S:38
Code: 44 88 1f e9 2e 8b b6 f5 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 e9 02 8b b6 f5 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900035770d0 EFLAGS: 00000202
RAX: ffffc90003577e00 RBX: ffffc900035771e0 RCX: 000000000000000a
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc900035771fe
RBP: dffffc0000000000 R08: ffffc90003577207 R09: ffffc900035771f8
R10: dffffc0000000000 R11: fffff520006aee41 R12: ffffc900035771f8
R13: 1ffff920006aee37 R14: ffffc900035771a8 R15: ffffc900035771f0
 unwind_next_frame+0xeae/0x23d0 arch/x86/kernel/unwind_orc.c:607
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2505
 shmem_alloc_folio mm/shmem.c:1890 [inline]
 shmem_alloc_and_add_folio+0x423/0xf40 mm/shmem.c:1932
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2556
 shmem_get_folio mm/shmem.c:2662 [inline]
 shmem_write_begin+0x16c/0x330 mm/shmem.c:3315
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3490
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5a8b78e1ff
RSP: 002b:00007f5a899f5df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f5a8b78e1ff
RDX: 0000000001000000 RSI: 00007f5a81400000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000097a0
R10: 0000200000012f42 R11: 0000000000000293 R12: 0000000000000003
R13: 00007f5a899f5ef0 R14: 00007f5a899f5eb0 R15: 00007f5a81400000
 </TASK>
task:syz.2.1935      state:R  running task     stack:25592 pid:14271 tgid:14270 ppid:5828   task_flags:0x400140 flags:0x00080004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7190
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:unwind_next_frame+0x18e3/0x23d0 arch/x86/kernel/unwind_orc.c:679
Code: 49 0f bf 04 24 48 01 c6 4c 89 f7 48 89 da e8 84 0d 00 00 84 c0 0f 84 47 01 00 00 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 20 <0f> b6 04 28 84 c0 0f 85 17 08 00 00 b3 01 8b 84 24 8c 00 00 00 41
RSP: 0018:ffffc9000c0e6fb8 EFLAGS: 00000202
RAX: 1ffff9200181ce11 RBX: ffffffff909b62cc RCX: 0000000000000001
RDX: ffffc9000c0e70c8 RSI: dffffc0000000000 RDI: ffffc9000c0e7510
RBP: dffffc0000000000 R08: ffffc9000c0e7510 R09: ffffc9000c0e70d8
R10: dffffc0000000000 R11: fffff5200181ce1d R12: ffffc9000c0e70d8
R13: 1ffff9200181ce13 R14: ffffc9000c0e7088 R15: 1ffffffff2136c59
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6670 [inline]
 kfree+0x1c0/0x660 mm/slub.c:6878
 skb_release_data+0x62d/0x7c0 net/core/skbuff.c:1107
 skb_release_all net/core/skbuff.c:1182 [inline]
 __kfree_skb net/core/skbuff.c:1196 [inline]
 consume_skb+0x9e/0xf0 net/core/skbuff.c:1428
 unix_dgram_sendmsg+0x570/0x1840 net/unix/af_unix.c:2298
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 sock_write_iter+0x279/0x360 net/socket.c:1195
 io_write+0xb33/0x16d0 io_uring/rw.c:1166
 __io_issue_sqe+0x181/0x4b0 io_uring/io_uring.c:1792
 io_issue_sqe+0x165/0x1060 io_uring/io_uring.c:1815
 io_queue_sqe io_uring/io_uring.c:2042 [inline]
 io_submit_sqe io_uring/io_uring.c:2320 [inline]
 io_submit_sqes+0xbf4/0x2140 io_uring/io_uring.c:2434
 __do_sys_io_uring_enter io_uring/io_uring.c:3280 [inline]
 __se_sys_io_uring_enter+0x2e0/0x2b60 io_uring/io_uring.c:3219
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f44ef78f749
RSP: 002b:00007f44f06eb038 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 00007f44ef9e5fa0 RCX: 00007f44ef78f749
RDX: 0000000000003e82 RSI: 00000000000047ba RDI: 0000000000000006
RBP: 00007f44ef813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000060 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f44ef9e6038 R14: 00007f44ef9e5fa0 R15: 00007ffc27c40c68
 </TASK>
rcu: rcu_preempt kthread starved for 10267 jiffies! g72065 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:27648 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6960
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
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+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 3e b4 b6 f5 cc cc cc 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 73 c1 0e 00 f3 0f 1e fa fb f4 <e9> 13 b4 b6 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8dc07dc0 EFLAGS: 000002c2
RAX: 0000000000a14415 RBX: ffffffff819713be RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8d792008 RDI: ffffffff8bc083e0
RBP: ffffffff8dc07eb0 R08: ffff8880b86336db R09: 1ffff110170c66db
R10: dffffc0000000000 R11: ffffed10170c66dc R12: ffffffff8f822170
R13: 1ffffffff1b92a68 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f391acd29ba CR3: 0000000027c04000 CR4: 0000000000350ef0
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+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1be/0x4d0 kernel/sched/idle.c:332
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430
 rest_init+0x2de/0x300 init/main.c:757
 start_kernel+0x381/0x3d0 init/main.c:1206
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x147
 </TASK>