syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7942/1:b..l
	(detected by 1, t=10502 jiffies, g=32113, q=178 ncpus=2)
task:syz.6.1012      state:R  running task     stack:25232 pid:7942  ppid:6004   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5666
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 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 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc9000db2f360 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 7d8af622a546ef00
RDX: 0000000000000000 RSI: ffffffff8a8c23a0 RDI: ffffffff8adf0de0
RBP: ffffc9000db2f480 R08: dffffc0000000000 R09: 1ffffffff215ea48
R10: dffffc0000000000 R11: fffffbfff215ea49 R12: 0000000000000000
R13: 1ffff92001b65e78 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 percpu_ref_get_many+0x35/0x140 include/linux/percpu-refcount.h:202
 percpu_ref_get include/linux/percpu-refcount.h:222 [inline]
 css_get include/linux/cgroup.h:327 [inline]
 charge_memcg+0x159/0x3a0 mm/memcontrol.c:6927
 __mem_cgroup_charge+0x21/0x80 mm/memcontrol.c:6944
 mem_cgroup_charge include/linux/memcontrol.h:672 [inline]
 shmem_add_to_page_cache+0x90d/0x1c50 mm/shmem.c:708
 shmem_get_folio_gfp+0x158e/0x3400 mm/shmem.c:1971
 shmem_fault+0x1b6/0x780 mm/shmem.c:2156
 __do_fault+0x13b/0x4e0 mm/memory.c:4278
 do_read_fault mm/memory.c:4629 [inline]
 do_fault mm/memory.c:4758 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x2407/0x3ee0 mm/memory.c:5292
 faultin_page mm/gup.c:1026 [inline]
 __get_user_pages+0x40d/0xec0 mm/gup.c:1250
 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607
 __mm_populate+0x25c/0x380 mm/gup.c:1721
 mm_populate include/linux/mm.h:2891 [inline]
 vm_mmap_pgoff+0x212/0x2d0 mm/util.c:525
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f53fc79c629
RSP: 002b:00007f53fa9d5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f53fca16090 RCX: 00007f53fc79c629
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f53fc832b39 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f53fca16128 R14: 00007f53fca16090 R15: 00007fff6aaf93e8
 </TASK>
rcu: rcu_preempt kthread starved for 9113 jiffies! g32113 f0x0 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:26864 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:742
Code: 48 89 df e8 27 c3 9c f7 e9 44 ff ff ff e8 3d 07 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 77 0c 50 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffc90000177de8 EFLAGS: 000002c6
RAX: 2470cf7b350d2f00 RBX: ffffffff8a36a2b7 RCX: 2470cf7b350d2f00
RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0de0
RBP: ffffc90000177f20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 1ffff9200002efc8
R13: dffffc0000000000 R14: ffff888017739dc0 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe98f2ebfe8 CR3: 000000001e78b000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x20d/0x5a0 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 start_secondary+0xe4/0xf0 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>