syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6571/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=13093, q=196 ncpus=2)
task:syz.1.156       state:R  running task     stack:24712 pid:6571  ppid:5780   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010
 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:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc9000ff4edc0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: e76d7a9f4a897f00
RDX: 0000000000000000 RSI: ffffffff8aaacbc0 RDI: ffffffff8afc6780
RBP: ffffc9000ff4eec8 R08: dffffc0000000000 R09: 1ffffffff21b46a4
R10: dffffc0000000000 R11: fffffbfff21b46a5 R12: 1ffff92001fe9dc4
R13: ffffffff8cd2fba0 R14: 0000000000000246 R15: dffffc0000000000
 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_lock+0x47/0x1e0 mm/pgtable-generic.c:371
 pte_offset_map_lock include/linux/mm.h:2950 [inline]
 do_anonymous_page mm/memory.c:4169 [inline]
 do_pte_missing mm/memory.c:3686 [inline]
 handle_pte_fault mm/memory.c:5025 [inline]
 __handle_mm_fault mm/memory.c:5166 [inline]
 handle_mm_fault+0x328c/0x4920 mm/memory.c:5331
 do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373
 handle_page_fault arch/x86/mm/fault.c:1465 [inline]
 exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:71
Code: 75 f1 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 <f3> a4 c3 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01
RSP: 0018:ffffc9000ff4f310 EFLAGS: 00050206
RAX: ffffffff841bff01 RBX: 0000000000001000 RCX: 0000000000000b80
RDX: 0000000000000000 RSI: ffff88800fc71480 RDI: 00002000001a0000
RBP: ffffc9000ff4f488 R08: ffff88800fc71fff R09: 1ffff11001f8e3ff
R10: dffffc0000000000 R11: ffffed1001f8e400 R12: 00002000001a0b80
R13: ffffc9000ff4fd40 R14: 000020000019fb80 R15: ffff88800fc71000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
 copyout+0x70/0x90 lib/iov_iter.c:168
 _copy_to_iter+0x432/0x10d0 lib/iov_iter.c:316
 __skb_datagram_iter+0x2ff/0x780 net/core/datagram.c:449
 skb_copy_datagram_iter+0xb1/0x200 net/core/datagram.c:535
 skb_copy_datagram_msg include/linux/skbuff.h:3991 [inline]
 unix_stream_read_actor+0x6c/0xa0 net/unix/af_unix.c:2931
 unix_stream_read_generic+0xd4b/0x2020 net/unix/af_unix.c:2850
 unix_stream_recvmsg+0x158/0x1b0 net/unix/af_unix.c:2968
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg net/socket.c:1068 [inline]
 ____sys_recvmsg+0x29e/0x5b0 net/socket.c:2814
 ___sys_recvmsg+0x1b6/0x510 net/socket.c:2856
 do_recvmmsg+0x360/0x7d0 net/socket.c:2950
 __sys_recvmmsg net/socket.c:3029 [inline]
 __do_sys_recvmmsg net/socket.c:3052 [inline]
 __se_sys_recvmmsg net/socket.c:3045 [inline]
 __x64_sys_recvmmsg+0x191/0x240 net/socket.c:3045
 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: 0033:0x7f4a3858ebe9
RSP: 002b:00007f4a39449038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f4a387b6090 RCX: 00007f4a3858ebe9
RDX: 040000000000013c RSI: 00002000000034c0 RDI: 0000000000000006
RBP: 00007f4a38611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000700 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4a387b6128 R14: 00007f4a387b6090 R15: 00007ffd0f95ac98
 </TASK>
rcu: rcu_preempt kthread starved for 9932 jiffies! g13093 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:27464 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.6.101-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:unwind_next_frame+0xde/0x2970 arch/x86/kernel/unwind_orc.c:482
Code: bf 01 00 00 00 e8 e2 ce 20 00 49 8d 6c 24 50 48 89 e8 48 c1 e8 03 48 89 44 24 50 42 80 3c 28 00 74 08 48 89 ef e8 f2 37 a2 00 <4c> 8b 75 00 4d 85 f6 74 44 49 81 c6 88 00 00 00 4c 89 f0 48 c1 e8
RSP: 0018:ffffc90000007598 EFLAGS: 00000246
RAX: 1ffff92000000ed7 RBX: 1ffff92000000ecd RCX: ffffffff96eaa403
RDX: ffffffff8ca93380 RSI: 0000000000000002 RDI: 0000000000000001
RBP: ffffc900000076b8 R08: ffffc90000007730 R09: 0000000000000001
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000007668
R13: dffffc0000000000 R14: ffffc900000076a0 R15: ffffffff81dcd50e
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000001a0000 CR3: 000000002e5e5000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1806 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
 slab_free mm/slub.c:3816 [inline]
 kmem_cache_free+0xf8/0x280 mm/slub.c:3838
 skb_kfree_head net/core/skbuff.c:943 [inline]
 skb_free_head net/core/skbuff.c:957 [inline]
 skb_release_data+0x60a/0x800 net/core/skbuff.c:987
 skb_release_all net/core/skbuff.c:1053 [inline]
 __kfree_skb net/core/skbuff.c:1067 [inline]
 consume_skb+0xb2/0x110 net/core/skbuff.c:1283
 mac80211_hwsim_beacon_tx+0x3e9/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
 __run_hrtimer kernel/time/hrtimer.c:1755 [inline]
 __hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1819
 hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1836
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
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 83 16 3b 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:ffffffff8ca07d80 EFLAGS: 000002c2
RAX: f7735e5571c1f000 RBX: ffffffff81619a6b RCX: f7735e5571c1f000
RDX: 0000000000000001 RSI: ffffffff8aaaba40 RDI: ffffffff8afc6780
RBP: ffffffff8ca07eb8 R08: ffff8880b8e36d4b R09: 1ffff110171c6da9
R10: dffffc0000000000 R11: ffffed10171c6daa R12: ffffffff8e4a84e8
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670
 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
 rest_init+0x2e2/0x300 init/main.c:732
 arch_call_rest_init+0xe/0x10 init/main.c:829
 start_kernel+0x459/0x4e0 init/main.c:1074
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>