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SubjectINFO: rcu detected stall in new_sync_read

syzbot found the following crash on:

HEAD commit: bed72351 Merge tag 'kbuild-fixes-v5.5-2' of git://git.kern..
git tree: upstream
console output:
kernel config:
dashboard link:
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:
C reproducer:

IMPORTANT: if you fix the bug, please add the following tag to the commit:

hrtimer: interrupt took 31901 ns
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 1, t=10502 jiffies, g=10557, q=3)
rcu: All QSes seen, last rcu_preempt kthread activity 10502
(4295016188-4295005686), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor724 R running task 23704 10332 10322 0x80004000
Call Trace:
sched_show_task kernel/sched/core.c:5954 [inline]
sched_show_task.cold+0x2ee/0x35d kernel/sched/core.c:5929
print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:538 [inline]
rcu_pending kernel/rcu/tree.c:2827 [inline]
rcu_sched_clock_irq.cold+0xaf4/0xc02 kernel/rcu/tree.c:2271
update_process_times+0x2d/0x70 kernel/time/timer.c:1726
tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310
__run_hrtimer kernel/time/hrtimer.c:1517 [inline]
__hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752
RIP: 0010:rmqueue_pcplist mm/page_alloc.c:3257 [inline]
RIP: 0010:rmqueue mm/page_alloc.c:3274 [inline]
RIP: 0010:get_page_from_freelist+0x1a6c/0x4290 mm/page_alloc.c:3692
Code: c0 d8 34 93 89 48 c1 e8 03 80 3c 18 00 0f 85 ae 25 00 00 48 83 3d 6b
43 e9 07 00 0f 84 82 09 00 00 48 8b bd 68 fe ff ff 57 9d <0f> 1f 44 00 00
e9 44 fc ff ff 48 8b 85 40 ff ff ff 48 8d 78 18 48
RSP: 0018:ffffc90001f1e9e8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff132669b RBX: dffffc0000000000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000282
RBP: ffffc90001f1eb98 R08: 1ffffffff1659dbc R09: fffffbfff1659dbd
R10: fffffbfff1659dbc R11: ffffffff8b2cede7 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000000 R15: ffffea0000ce29c8
__alloc_pages_nodemask+0x2d0/0x910 mm/page_alloc.c:4756
alloc_pages_current+0x107/0x210 mm/mempolicy.c:2207
alloc_pages include/linux/gfp.h:532 [inline]
__page_cache_alloc+0x29d/0x490 mm/filemap.c:981
__do_page_cache_readahead+0x1c9/0x5d0 mm/readahead.c:196
ra_submit mm/internal.h:62 [inline]
ondemand_readahead+0x55c/0xd30 mm/readahead.c:492
page_cache_async_readahead mm/readahead.c:574 [inline]
page_cache_async_readahead+0x437/0x7c0 mm/readahead.c:547
generic_file_buffered_read mm/filemap.c:2059 [inline]
generic_file_read_iter+0x13c0/0x2cf0 mm/filemap.c:2324
ext4_file_read_iter fs/ext4/file.c:130 [inline]
ext4_file_read_iter+0x1db/0x640 fs/ext4/file.c:113
call_read_iter include/linux/fs.h:1896 [inline]
new_sync_read+0x4d7/0x800 fs/read_write.c:414
__vfs_read+0xe1/0x110 fs/read_write.c:427
integrity_kernel_read+0x157/0x210 security/integrity/iint.c:200
ima_calc_file_hash_tfm+0x2e3/0x3e0 security/integrity/ima/ima_crypto.c:360
ima_calc_file_shash security/integrity/ima/ima_crypto.c:389 [inline]
ima_calc_file_hash+0x1aa/0x570 security/integrity/ima/ima_crypto.c:454
ima_collect_measurement+0x534/0x5f0 security/integrity/ima/ima_api.c:247
process_measurement+0xd45/0x1850 security/integrity/ima/ima_main.c:326
ima_file_check+0xc5/0x110 security/integrity/ima/ima_main.c:442
do_last fs/namei.c:3424 [inline]
path_openat+0x1138/0x4500 fs/namei.c:3537
do_filp_open+0x1a1/0x280 fs/namei.c:3567
do_sys_open+0x3fe/0x5d0 fs/open.c:1097
__do_sys_open fs/open.c:1115 [inline]
__se_sys_open fs/open.c:1110 [inline]
__x64_sys_open+0x7e/0xc0 fs/open.c:1110
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
RIP: 0033:0x4476f9
Code: e8 3c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 ab 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe778c7edb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00000000006ddc28 RCX: 00000000004476f9
RDX: 0000000000000000 RSI: 0000000000141042 RDI: 0000000020000100
RBP: 00000000006ddc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc2c
R13: 00007ffd2d04e6ff R14: 00007fe778c7f9c0 R15: 0000000000000000
rcu: rcu_preempt kthread starved for 10502 jiffies! g10557 f0x2
RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt R running task 29264 10 2 0x80004000
Call Trace:
context_switch kernel/sched/core.c:3385 [inline]
__schedule+0x934/0x1f90 kernel/sched/core.c:4081
schedule+0xdc/0x2b0 kernel/sched/core.c:4155
schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895
rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
rcu_gp_kthread+0x9b2/0x18d0 kernel/rcu/tree.c:1821
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

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