syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7833/1:b..l
	(detected by 1, t=10503 jiffies, g=34849, q=70 ncpus=2)
task:syz.2.735       state:R  running task     stack:26480 pid:7833  ppid:4268   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:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:215
Code: 00 00 00 00 00 90 53 48 89 fb e8 17 00 00 00 48 8b 3d 40 5a 9d 0c 48 89 de 5b e9 47 22 50 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d 14 fa 7f 7e 65 8b 15 15 fa 7f 7e 81 e2 00 01 ff 00 74
RSP: 0000:ffffc9000458f718 EFLAGS: 00000282
RAX: ffffffff8a19fcb8 RBX: 0000000000000000 RCX: 0000000000000007
RDX: ffffffff8a19fca3 RSI: ffffffff8e08ab70 RDI: ffff888079d7221c
RBP: ffffc9000458f830 R08: ffff88802c22d940 R09: 0000000000000002
R10: 0000000000000009 R11: 0000000000000002 R12: dffffc0000000000
R13: ffff888079d7221c R14: ffffffffffffff00 R15: 0000000000000002
 mas_state_walk lib/maple_tree.c:3903 [inline]
 mt_find+0x238/0x830 lib/maple_tree.c:6539
 find_vma+0x12c/0x1b0 mm/mmap.c:1898
 lock_mm_and_find_vma+0x71/0x2f0 mm/memory.c:5385
 do_user_addr_fault+0x2db/0xb10 arch/x86/mm/fault.c:1310
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:fault_in_readable+0x13e/0x1f0 mm/gup.c:1915
Code: d8 60 c4 ff 4d 89 f4 49 81 cc ff 0f 00 00 4d 89 f7 49 01 dc 49 81 e4 00 f0 ff ff 4d 39 e6 77 44 e8 b7 60 c4 ff 4d 39 e7 74 47 <41> 8a 07 88 44 24 07 49 81 c7 00 10 00 00 4d 39 e7 74 07 e8 9a 60
RSP: 0000:ffffc9000458fab0 EFLAGS: 00050287
RAX: ffffffff81be1469 RBX: 0000000000001000 RCX: 0000000000080000
RDX: ffffc9000c761000 RSI: 000000000007358e RDI: 000000000007358f
RBP: 0000000000000000 R08: ffff88802c22d940 R09: 0000000000000002
R10: 0000000000000006 R11: 0000000000000002 R12: 0000200000260000
R13: 0000000000000000 R14: 000020000025eff7 R15: 000020000025f000
 fault_in_iov_iter_readable+0xbb/0x2e0 lib/iov_iter.c:356
 generic_perform_write+0x1f1/0x5c0 mm/filemap.c:3852
 __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4b1/0xa30 fs/read_write.c:584
 ksys_write+0x14c/0x250 fs/read_write.c:637
 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: 0033:0x7f1af3d9c629
RSP: 002b:00007f1af1ff6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1af4015fa0 RCX: 00007f1af3d9c629
RDX: 000000000208e24b RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f1af3e32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1af4016038 R14: 00007f1af4015fa0 R15: 00007ffe0998d758
 </TASK>
rcu: rcu_preempt kthread starved for 10528 jiffies! g34849 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:27760 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: f16f251417294600 RBX: ffffffff8a36a2b7 RCX: f16f251417294600
RDX: 0000000000000001 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0de0
RBP: ffffc90000177f20 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 1ffff9200002efc8
R13: dffffc0000000000 R14: ffff88813fef9dc0 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005581e8e21a38 CR3: 000000000c88e000 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>