syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P13135/1:b..l
	(detected by 0, t=10503 jiffies, g=66397, q=178 ncpus=2)
task:syz.6.2277      state:R  running task     stack:25248 pid:13135 ppid:6816   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 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:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_acquire+0x15e/0x490 kernel/locking/lockdep.c:5658
Code: 89 f0 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 19 02 00 00 41 83 3e 00 0f 85 02 01 00 00 48 c7 84 24 a0 00 00 00 00 00 00 00 9c <8f> 84 24 a0 00 00 00 4c 8b b4 24 a0 00 00 00 fa 48 c7 c7 40 11 8c
RSP: 0018:ffffc9000385f3f8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: d7b8308c6322f900
RDX: 0000000000000000 RSI: ffffffff8adef240 RDI: ffffffff8adef200
RBP: ffffc9000385f510 R08: dffffc0000000000 R09: fffffbfff1c3e91e
R10: fffffbfff1c3e91e R11: 1ffffffff1c3e91d R12: 0000000000000001
R13: 1ffff9200070be8c R14: ffff88802d9f8adc R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 get_mem_cgroup_from_mm+0x50/0x290 mm/memcontrol.c:1036
 __mem_cgroup_charge+0x11/0x80 mm/memcontrol.c:6943
 mem_cgroup_charge include/linux/memcontrol.h:672 [inline]
 shmem_add_to_page_cache+0x8fc/0x1c00 mm/shmem.c:708
 shmem_get_folio_gfp+0x158b/0x3400 mm/shmem.c:1971
 shmem_fault+0x1be/0x7b0 mm/shmem.c:2156
 __do_fault+0x13b/0x4e0 mm/memory.c:4280
 do_read_fault mm/memory.c:4631 [inline]
 do_fault mm/memory.c:4760 [inline]
 handle_pte_fault mm/memory.c:5031 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x28ca/0x3e70 mm/memory.c:5294
 faultin_page mm/gup.c:1026 [inline]
 __get_user_pages+0x3ff/0xeb0 mm/gup.c:1250
 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607
 __mm_populate+0x248/0x370 mm/gup.c:1721
 mm_populate include/linux/mm.h:2826 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fefb238e9a9
RSP: 002b:00007fefb3182038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fefb25b5fa0 RCX: 00007fefb238e9a9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007fefb2410d69 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fefb25b5fa0 R15: 00007fffd2e71018
 </TASK>
rcu: rcu_preempt kthread starved for 10534 jiffies! g66397 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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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: 0 PID: 13154 Comm: syz.1.2279 Not tainted 6.1.146-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: f5 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ce 41 43 f7 48 89 df e8 26 07 44 f7 e8 41 f9 66 f7 fb bf 01 00 00 00 <e8> 36 84 37 f7 65 8b 05 07 45 e2 75 85 c0 74 02 5b c3 e8 54 56 e0
RSP: 0018:ffffc90003327bb8 EFLAGS: 00000286
RAX: 1f0dfc676383f800 RBX: ffff888055ec1280 RCX: 1f0dfc676383f800
RDX: dffffc0000000000 RSI: ffffffff8a8c0460 RDI: 0000000000000001
RBP: 1ffff11005c29885 R08: dffffc0000000000 R09: ffffed100abd8251
R10: ffffed100abd8251 R11: 1ffff1100abd8250 R12: ffff8880463d26e0
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8880463d26f8
FS:  00007fcbfe2a96c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcbfe2a8e80 CR3: 0000000075b83000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x1163/0x1350 kernel/signal.c:2874
 arch_do_signal_or_restart+0xb0/0x1230 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcbfd38e9a9
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:00007fcbfe2a90e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fcbfd5b6088 RCX: 00007fcbfd38e9a9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fcbfd5b6088
RBP: 00007fcbfd5b6080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcbfd5b608c
R13: 0000000000000000 R14: 00007ffc2f016c30 R15: 00007ffc2f016d18
 </TASK>