INFO: rcu detected stall in kmem_cache_free

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 1c046f37 Linux 4.14.115
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1671d9c0a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=453b2eab9a394b3e
dashboard link: https://syzkaller.appspot.com/bug?extid=bc35f60414d5069e5c46
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bc35f6...@syzkaller.appspotmail.com

INFO: rcu_sched self-detected stall on CPU
1-...: (10500 ticks this GP) idle=a6a/140000000000001/0
softirq=159464/159465 fqs=0
(t=10501 jiffies g=24025 c=24024 q=135)
rcu_sched kthread starved for 10501 jiffies! g24025 c24024 f0x0
RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1
rcu_sched R running task 29776 9 2 0x80000000
Call Trace:
context_switch kernel/sched/core.c:2807 [inline]
__schedule+0x7be/0x1cf0 kernel/sched/core.c:3383
schedule+0x92/0x1c0 kernel/sched/core.c:3427
schedule_timeout+0x43e/0xe10 kernel/time/timer.c:1744
rcu_gp_kthread+0xbf4/0x1ec0 kernel/rcu/tree.c:2255
kthread+0x31c/0x430 kernel/kthread.c:232
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9790 Comm: syz-executor.5 Not tainted 4.14.115 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff888095c884c0 task.stack: ffff88807c5f0000
RIP: 0010:__read_once_size include/linux/compiler.h:186 [inline]
RIP: 0010:raw_read_seqcount_latch include/linux/seqlock.h:281 [inline]
RIP: 0010:latch_tree_find include/linux/rbtree_latch.h:206 [inline]
RIP: 0010:bpf_prog_kallsyms_find kernel/bpf/core.c:418 [inline]
RIP: 0010:bpf_prog_kallsyms_find+0x70/0x280 kernel/bpf/core.c:411
RSP: 0018:ffff88807c5f7a28 EFLAGS: 00000297
RAX: ffff888095c884c0 RBX: 0000000000000000 RCX: 1ffffffff0e9c1a4
RDX: 0000000000000000 RSI: ffffffff869bee00 RDI: 0000000000000000
RBP: ffff88807c5f7a68 R08: 0000000000000000 R09: ffff888095c88d60
R10: ffff888095c88d40 R11: ffff888095c884c0 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888095c884c0 R15: 0000000000000000
FS: 00007fe171bf8700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000073a20000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
is_bpf_text_address+0x61/0x120 kernel/bpf/core.c:453
kernel_text_address+0x73/0xf0 kernel/extable.c:150
__kernel_text_address+0xd/0x40 kernel/extable.c:105
unwind_get_return_address arch/x86/kernel/unwind_frame.c:18 [inline]
unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:13
__save_stack_trace+0x7b/0xd0 arch/x86/kernel/stacktrace.c:45
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x45/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc mm/kasan/kasan.c:551 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
slab_post_alloc_hook mm/slab.h:442 [inline]
slab_alloc mm/slab.c:3390 [inline]
kmem_cache_alloc+0x11b/0x780 mm/slab.c:3550
prepare_creds+0x3e/0x340 kernel/cred.c:252
SYSC_setregid kernel/sys.c:355 [inline]
SyS_setregid+0xd3/0x5c0 kernel/sys.c:339
do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x2000040f
RSP: 002b:00007fe171bf7bd8 EFLAGS: 00000207 ORIG_RAX: 0000000000000072
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 000000002000040f
RDX: 3deb3210b8c987ca RSI: 0000000000000000 RDI: 0000000000000000
RBP: 000000000000005a R08: 0000000000000005 R09: 0000000000000006
R10: 0000000000000007 R11: 0000000000000207 R12: 000000000000000b
R13: 000000000000000c R14: 000000000000000d R15: 00000000ffffffff
Code: 41 5e 41 5f 5d c3 49 bd 00 00 00 00 00 fc ff df eb 14 e8 a4 1f f7 ff
8b 45 cc 3b 05 4b f2 fa 05 0f 84 53 01 00 00 e8 90 1f f7 ff <8b> 05 3a f2
fa 05 89 c3 89 45 cc 83 e3 01 4c 8d 63 05 4a 8d 3c
NMI backtrace for cpu 1
CPU: 1 PID: 17 Comm: ksoftirqd/1 Not tainted 4.14.115 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x19c lib/dump_stack.c:53
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_single_cpu_backtrace include/linux/nmi.h:158 [inline]
rcu_dump_cpu_stacks+0x186/0x1d2 kernel/rcu/tree.c:1396
print_cpu_stall kernel/rcu/tree.c:1542 [inline]
check_cpu_stall kernel/rcu/tree.c:1610 [inline]
__rcu_pending kernel/rcu/tree.c:3390 [inline]
rcu_pending kernel/rcu/tree.c:3452 [inline]
rcu_check_callbacks.cold+0x43d/0xd0a kernel/rcu/tree.c:2792
update_process_times+0x31/0x70 kernel/time/timer.c:1588
tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:161
tick_sched_timer+0x43/0x130 kernel/time/tick-sched.c:1219
__run_hrtimer kernel/time/hrtimer.c:1220 [inline]
__hrtimer_run_queues+0x273/0xbd0 kernel/time/hrtimer.c:1284
hrtimer_interrupt+0x1d8/0x5d0 kernel/time/hrtimer.c:1318
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
smp_apic_timer_interrupt+0x12c/0x600 arch/x86/kernel/apic/apic.c:1062
apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:787
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:778
[inline]
RIP: 0010:kmem_cache_free+0xb0/0x2b0 mm/slab.c:3759
RSP: 0018:ffff8880a9d67c60 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000007 RBX: ffff88821616e700 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8880a9d5cd00 RDI: 0000000000000282
RBP: ffff8880a9d67c80 R08: 00000000927d8e98 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88821f830640
R13: 0000000000000282 R14: ffffffff813eca76 R15: dffffc0000000000
put_cred_rcu+0x236/0x300 kernel/cred.c:126
__rcu_reclaim kernel/rcu/rcu.h:195 [inline]
rcu_do_batch kernel/rcu/tree.c:2699 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
rcu_process_callbacks+0x7c0/0x12c0 kernel/rcu/tree.c:2946
__do_softirq+0x24e/0x9ae kernel/softirq.c:288
run_ksoftirqd kernel/softirq.c:670 [inline]
run_ksoftirqd+0x8c/0x1b0 kernel/softirq.c:662
smpboot_thread_fn+0x5fd/0x970 kernel/smpboot.c:164
kthread+0x31c/0x430 kernel/kthread.c:232
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.