syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11557/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=35841, q=278 ncpus=2)
task:syz.1.1515      state:R  running task     stack:25544 pid:11557 tgid:11556 ppid:5808   task_flags:0x20400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7256
 irqentry_exit+0x36/0x90 kernel/entry/common.c:211
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pmd_none arch/x86/include/asm/pgtable.h:1018 [inline]
RIP: 0010:___pte_offset_map+0xaa/0x4f0 mm/pgtable-generic.c:293
Code: 00 4d 85 e4 74 24 e8 75 71 ac ff 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 0e 04 00 00 49 89 1c 24 <e8> 51 71 ac ff 49 89 dc 31 ff 49 83 e4 9f 4c 89 e6 e8 b0 6c ac ff
RSP: 0018:ffffc9000fd2ef28 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000057c56067 RCX: ffffc9000c739000
RDX: 1ffff92001fa5df2 RSI: ffffffff8210765b RDI: 0000000000000001
RBP: 0000200000869000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffffc9000fd2ef90
R13: ffff88807bb65020 R14: ffffc9000fd2f058 R15: 1ffff92001fa5e07
 __pte_offset_map include/linux/mm.h:3125 [inline]
 __pte_offset_map_lock+0x8d/0x310 mm/pgtable-generic.c:397
 pte_offset_map_lock include/linux/mm.h:3140 [inline]
 follow_page_pte+0xab/0x1390 mm/gup.c:812
 follow_pmd_mask mm/gup.c:928 [inline]
 follow_pud_mask mm/gup.c:967 [inline]
 follow_p4d_mask mm/gup.c:984 [inline]
 follow_page_mask mm/gup.c:1023 [inline]
 __get_user_pages+0x918/0x3530 mm/gup.c:1426
 __get_user_pages_locked mm/gup.c:1692 [inline]
 __gup_longterm_locked+0xa92/0x17e0 mm/gup.c:2476
 gup_fast_fallback+0xee2/0x22a0 mm/gup.c:3220
 pin_user_pages_fast+0xa7/0xf0 mm/gup.c:3326
 iov_iter_extract_user_pages lib/iov_iter.c:1751 [inline]
 iov_iter_extract_pages+0x3a2/0x1ed0 lib/iov_iter.c:1814
 __bio_iov_iter_get_pages block/bio.c:1234 [inline]
 bio_iov_iter_get_pages+0x395/0x1300 block/bio.c:1356
 blkdev_iov_iter_get_pages block/fops.c:49 [inline]
 __blkdev_direct_IO block/fops.c:222 [inline]
 blkdev_direct_IO+0x128f/0x2100 block/fops.c:441
 blkdev_direct_write block/fops.c:726 [inline]
 blkdev_write_iter+0x703/0xe00 block/fops.c:794
 aio_write+0x3b9/0x910 fs/aio.c:1634
 __io_submit_one fs/aio.c:2006 [inline]
 io_submit_one+0x1243/0x1df0 fs/aio.c:2053
 __do_sys_io_submit fs/aio.c:2112 [inline]
 __se_sys_io_submit fs/aio.c:2082 [inline]
 __x64_sys_io_submit+0x1a9/0x350 fs/aio.c:2082
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcfb198f749
RSP: 002b:00007fcfb282c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007fcfb1be5fa0 RCX: 00007fcfb198f749
RDX: 00002000000000c0 RSI: 00000000000000f3 RDI: 00007fcfb280b000
RBP: 00007fcfb1a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcfb1be6038 R14: 00007fcfb1be5fa0 R15: 00007ffe1c7f59a8
 </TASK>
rcu: rcu_preempt kthread starved for 9557 jiffies! g35841 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:28552 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: a7 6c 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 83 55 29 00 fb f4 <e9> 3c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197de8 EFLAGS: 000002c6
RAX: 0000000002b264ab RBX: 0000000000000001 RCX: ffffffff8b60d2a9
RDX: 0000000000000000 RSI: ffffffff8da2c59c RDI: ffffffff8bf073c0
RBP: ffffed1003ad6490 R08: 0000000000000001 R09: ffffed10170a6655
R10: ffff8880b85332ab R11: 0000000000000001 R12: 0000000000000001
R13: ffff88801d6b2480 R14: ffffffff908216d0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124b05000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9da4593d58 CR3: 00000000742de000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:190 [inline]
 do_idle+0x38d/0x500 kernel/sched/idle.c:330
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x148
 </TASK>