syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=d71c/1/0x4000000000000000 softirq=38852/38865 fqs=1
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5811/1:b..l
rcu: 	(detected by 0, t=10505 jiffies, g=24893, q=531 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 10045 Comm: syz.3.911 Not tainted 6.15.0-rc6-syzkaller-00025-g627277ba7c23 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:411
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 e9 ab c6 bb f5 cc
RSP: 0018:ffffc90000a08db0 EFLAGS: 00000082
RAX: 0000000000000001 RBX: ffff8880b8527858 RCX: ffffffff93aad680
RDX: 0000000000000000 RSI: ffffffff8dbbd22b RDI: ffffffff8bf48920
RBP: 0000000000000000 R08: bc101d9a73125dae R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f76fbaae6c0(0000) GS:ffff888124adf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000097030 CR3: 00000000335f5000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lockdep_recursion_finish kernel/locking/lockdep.c:472 [inline]
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x189/0x350 kernel/locking/lockdep.c:5823
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:170
 __run_hrtimer kernel/time/hrtimer.c:1765 [inline]
 __hrtimer_run_queues+0x2bc/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__schedule+0x1177/0x5de0 kernel/sched/core.c:6773
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 17 49 00 00 49 89 5f 10 48 8b bd 10 ff ff ff 48 89 de e8 51 d7 bd f5 48 89 c7 e8 19 b8 1b f6 <48> 8b 75 08 8b bd 08 ff ff ff e8 ca 2b 1b f6 48 8b b5 88 fe ff ff
RSP: 0018:ffffc9000577f5d8 EFLAGS: 00000202
RAX: 00000000000076e5 RBX: ffff888059192440 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8dbe2848 RDI: ffffffff8bf48920
RBP: ffffc9000577f788 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff9084ff17 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888059192440 R15: ffff8880b8539dc0
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6947
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:194
 __unix_dgram_recvmsg+0x326/0xee0 net/unix/af_unix.c:2447
 unix_dgram_recvmsg+0xd0/0x110 net/unix/af_unix.c:2522
 sock_recvmsg_nosec net/socket.c:1017 [inline]
 ____sys_recvmsg+0x5f9/0x6b0 net/socket.c:2784
 ___sys_recvmsg+0x114/0x1a0 net/socket.c:2828
 do_recvmmsg+0x2fe/0x740 net/socket.c:2923
 __sys_recvmmsg net/socket.c:2997 [inline]
 __do_sys_recvmmsg net/socket.c:3020 [inline]
 __se_sys_recvmmsg net/socket.c:3013 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3013
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f76fab8e969
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:00007f76fbaae038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f76fadb6080 RCX: 00007f76fab8e969
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f76fac10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f76fadb6080 R15: 00007ffc0d07d198
 </TASK>
task:syz-executor    state:R  running task     stack:22640 pid:5811  tgid:5811  ppid:5802   task_flags:0x400140 flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6947
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 copy_pte_range mm/memory.c:1194 [inline]
 copy_pmd_range mm/memory.c:1255 [inline]
 copy_pud_range mm/memory.c:1292 [inline]
 copy_p4d_range mm/memory.c:1316 [inline]
 copy_page_range+0x1948/0x5f80 mm/memory.c:1410
 dup_mmap kernel/fork.c:726 [inline]
 dup_mm kernel/fork.c:1734 [inline]
 copy_mm kernel/fork.c:1786 [inline]
 copy_process+0x862b/0x91a0 kernel/fork.c:2429
 kernel_clone+0xfc/0x960 kernel/fork.c:2844
 __do_sys_clone+0xce/0x120 kernel/fork.c:2987
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb269851d3
RSP: 002b:00007ffeffd21208 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007feb269851d3
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 000055558ccd77d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 000000000007da63 R15: 00007ffeffd213a0
 </TASK>
rcu: rcu_preempt kthread starved for 10325 jiffies! g24893 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:27704 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5817 Comm: syz-executor Not tainted 6.15.0-rc6-syzkaller-00025-g627277ba7c23 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x17/0x70 kernel/kcov.c:217
Code: 03 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 34 24 65 48 8b 15 e8 c9 e8 11 65 8b 05 f9 c9 e8 11 <a9> 00 01 ff 00 74 1d f6 c4 01 74 43 a9 00 00 0f 00 75 3c a9 00 00
RSP: 0000:ffffc90005207960 EFLAGS: 00000202
RAX: 0000000000000003 RBX: ffff8880b853f740 RCX: ffffffff81af2ee9
RDX: ffff888031260000 RSI: ffffffff81af2ec3 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffed10170a7ee9
R13: 0000000000000001 R14: dffffc0000000000 R15: ffff8880b843b040
FS:  000055558b983500(0000) GS:ffff8881249df000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558b99e5c8 CR3: 0000000064976000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline]
 cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline]
 csd_lock_wait kernel/smp.c:340 [inline]
 smp_call_function_many_cond+0x4a3/0x1290 kernel/smp.c:885
 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1291 [inline]
 flush_tlb_mm_range+0x322/0x1780 arch/x86/mm/tlb.c:1381
 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline]
 ptep_clear_flush+0x136/0x180 mm/pgtable-generic.c:101
 wp_page_copy mm/memory.c:3544 [inline]
 do_wp_page+0x17c6/0x58e0 mm/memory.c:3939
 handle_pte_fault mm/memory.c:6013 [inline]
 __handle_mm_fault+0x1ada/0x2a40 mm/memory.c:6140
 handle_mm_fault+0x3fe/0xad0 mm/memory.c:6309
 do_user_addr_fault+0x60c/0x1370 arch/x86/mm/fault.c:1337
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f76fab4cdbf
Code: 8d 34 19 48 39 d5 48 89 75 60 0f 95 c2 48 29 d8 48 83 c1 10 0f b6 d2 48 83 c8 01 48 c1 e2 02 48 09 da 48 83 ca 01 48 89 51 f8 <48> 89 46 08 eb 80 48 8d 0d 01 d1 0e 00 48 8d 15 05 e3 0e 00 bf 01
RSP: 002b:00007ffc0d07d3c0 EFLAGS: 00010206
RAX: 0000000000018a41 RBX: 0000000000008040 RCX: 000055558b996590
RDX: 0000000000008041 RSI: 000055558b99e5c0 RDI: 0000000000000004
RBP: 00007f76fad83ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000802 R12: 0000000000008030
R13: 0000000000000076 R14: 00007f76fad83d00 R15: 0000000000000000
 </TASK>