syzbot

GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=105085, q=97 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295039088-4295028586), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g105085 f0x2 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:27848 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 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: 18282 Comm: syz.3.3716 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:hrtimer_get_softexpires_tv64 include/linux/hrtimer.h:295 [inline]
RIP: 0010:__hrtimer_run_queues+0x23e/0xc10 kernel/time/hrtimer.c:1815
Code: 89 44 24 40 48 89 4c 24 18 48 c1 e9 03 48 89 4c 24 28 48 8b 9c 24 e0 00 00 00 4d 8d 75 20 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 88 7c 68 00 4d 8b 36 48 89 df 4c 89 f6 e8 1a 0a
RSP: 0018:ffffc900001f0d60 EFLAGS: 00000046
RAX: 1ffff1100fb89e6c RBX: 1bc16d683d33b595 RCX: ffff8880488e9e00
RDX: 0000000000010000 RSI: 1ffff110171e572a RDI: ffff88807dc4f340
RBP: ffffc900001f0eb8 R08: ffff88807dc4f357 R09: 0000000000000000
R10: ffff88807dc4f340 R11: ffffed100fb89e6b R12: ffff8880b8f2b940
R13: ffff88807dc4f340 R14: ffff88807dc4f360 R15: dffffc0000000000
FS:  00007f938b6ce6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000062000 CR3: 0000000052bb8000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 hrtimer_interrupt+0x39d/0x980 kernel/time/hrtimer.c:1880
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/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:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 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 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000d12f3a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f994177cd0a89700
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1c7be0
RBP: ffffc9000d12f4a8 R08: dffffc0000000000 R09: 1ffffffff22378a0
R10: dffffc0000000000 R11: fffffbfff22378a1 R12: 1ffff92001a25e80
R13: ffffffff8d131e60 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock_sched include/linux/rcupdate.h:878 [inline]
 pfn_valid+0xe9/0x420 include/linux/mmzone.h:2011
 page_table_check_set+0x25/0x6e0 mm/page_table_check.c:110
 page_table_check_ptes_set include/linux/page_table_check.h:74 [inline]
 set_ptes include/linux/pgtable.h:238 [inline]
 copy_present_pte mm/memory.c:979 [inline]
 copy_pte_range mm/memory.c:1083 [inline]
 copy_pmd_range mm/memory.c:1168 [inline]
 copy_pud_range mm/memory.c:1205 [inline]
 copy_p4d_range mm/memory.c:1229 [inline]
 copy_page_range+0x24fc/0x3700 mm/memory.c:1323
 dup_mmap kernel/fork.c:769 [inline]
 dup_mm kernel/fork.c:1694 [inline]
 copy_mm+0x1751/0x1e30 kernel/fork.c:1743
 copy_process+0x171d/0x3df0 kernel/fork.c:2508
 kernel_clone+0x24b/0x8a0 kernel/fork.c:2917
 __do_sys_clone kernel/fork.c:3060 [inline]
 __se_sys_clone kernel/fork.c:3044 [inline]
 __x64_sys_clone+0x1b7/0x230 kernel/fork.c:3044
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f938a79ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f938b6cdfd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f938aa15fa0 RCX: 00007f938a79ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000011
RBP: 00007f938a832e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f938aa16038 R14: 00007f938aa15fa0 R15: 00007ffc987430a8
 </TASK>