[syzbot] INFO: rcu detected stall in sys_recvmmsg

From: syzbot
Date: Tue Sep 21 2021 - 20:16:53 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 1f77990c4b79 Add linux-next specific files for 20210920
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1383891d300000
kernel config: https://syzkaller.appspot.com/x/.config?x=ab1346371f2e6884
dashboard link: https://syzkaller.appspot.com/bug?extid=3360da629681aa0d22fe
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1625f1ab300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17eb1b3b300000

The issue was bisected to:

commit 020250f31c4c75ac7687a673e29c00786582a5f4
Author: Dmitry Kadashev <dkadashev@xxxxxxxxx>
Date: Thu Jul 8 06:34:43 2021 +0000

namei: make do_linkat() take struct filename

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15f5ef77300000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17f5ef77300000
console output: https://syzkaller.appspot.com/x/log.txt?x=13f5ef77300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3360da629681aa0d22fe@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 020250f31c4c ("namei: make do_linkat() take struct filename")

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (10499 ticks this GP) idle=0af/1/0x4000000000000000 softirq=10678/10678 fqs=1
(t=10500 jiffies g=13089 q=109)
rcu: rcu_preempt kthread starved for 10497 jiffies! g13089 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:28696 pid: 14 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:4955 [inline]
__schedule+0x940/0x26f0 kernel/sched/core.c:6236
schedule+0xd3/0x270 kernel/sched/core.c:6315
schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1955
rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2128
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8510 Comm: syz-executor827 Not tainted 5.15.0-rc2-next-20210920-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0xc8/0x180 mm/kasan/generic.c:189
Code: 38 00 74 ed 48 8d 50 08 eb 09 48 83 c0 01 48 39 d0 74 7a 80 38 00 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 <48> 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00
RSP: 0018:ffffc9000cd676c8 EFLAGS: 00000283
RAX: ffffed100e9a110e RBX: ffffed100e9a110f RCX: ffffffff88ea062a
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff888074d08870
RBP: ffffed100e9a110e R08: 0000000000000001 R09: ffff888074d08877
R10: ffffed100e9a110e R11: 0000000000000000 R12: ffff888074d08000
R13: ffff888074d08000 R14: ffff888074d08088 R15: ffff888074d08000
FS: 0000555556d8e300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000180 CR3: 0000000068909000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
test_and_clear_bit include/asm-generic/bitops/instrumented-atomic.h:83 [inline]
mptcp_release_cb+0x14a/0x210 net/mptcp/protocol.c:3016
release_sock+0xb4/0x1b0 net/core/sock.c:3204
mptcp_wait_data net/mptcp/protocol.c:1770 [inline]
mptcp_recvmsg+0xfd1/0x27b0 net/mptcp/protocol.c:2080
inet6_recvmsg+0x11b/0x5e0 net/ipv6/af_inet6.c:659
sock_recvmsg_nosec net/socket.c:944 [inline]
____sys_recvmsg+0x527/0x600 net/socket.c:2626
___sys_recvmsg+0x127/0x200 net/socket.c:2670
do_recvmmsg+0x24d/0x6d0 net/socket.c:2764
__sys_recvmmsg net/socket.c:2843 [inline]
__do_sys_recvmmsg net/socket.c:2866 [inline]
__se_sys_recvmmsg net/socket.c:2859 [inline]
__x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2859
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fc200d2dc39
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc5758e5a8 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc200d2dc39
RDX: 0000000000000002 RSI: 00000000200017c0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000f0b5ff
R10: 0000000000000100 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffc5758e5d0 R14: 00007ffc5758e5c0 R15: 0000000000000003
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.444 msecs
NMI backtrace for cpu 0
CPU: 0 PID: 8509 Comm: syz-executor827 Not tainted 5.15.0-rc2-next-20210920-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343
print_cpu_stall kernel/rcu/tree_stall.h:627 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:711 [inline]
rcu_pending kernel/rcu/tree.c:3878 [inline]
rcu_sched_clock_irq.cold+0x9d/0x746 kernel/rcu/tree.c:2597
update_process_times+0x16d/0x200 kernel/time/timer.c:1785
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
__sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103
sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097
</IRQ>
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:lock_release+0x3f1/0x720 kernel/locking/lockdep.c:5633
Code: 7e 83 f8 01 0f 85 8d 01 00 00 9c 58 f6 c4 02 0f 85 78 01 00 00 48 f7 04 24 00 02 00 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c5 48 c7 45 00 00 00 00 00 c7 45 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc9000cde7660 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 70dbee1ebc366ab9 RCX: ffffc9000cde76b0
RDX: 1ffff11003a0bc2b RSI: 0000000000000201 RDI: 0000000000000000
RBP: 1ffff920019bcece R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000443 R12: 0000000000000001
R13: 0000000000000002 R14: ffff88801d05e160 R15: ffff88801d05d700
__raw_spin_unlock_bh include/linux/spinlock_api_smp.h:174 [inline]
_raw_spin_unlock_bh+0x12/0x30 kernel/locking/spinlock.c:210
spin_unlock_bh include/linux/spinlock.h:413 [inline]
unlock_sock_fast include/net/sock.h:1644 [inline]
unlock_sock_fast include/net/sock.h:1636 [inline]
mptcp_subflow_cleanup_rbuf net/mptcp/protocol.c:468 [inline]
mptcp_cleanup_rbuf net/mptcp/protocol.c:499 [inline]
mptcp_recvmsg+0xb8b/0x27b0 net/mptcp/protocol.c:2027
inet6_recvmsg+0x11b/0x5e0 net/ipv6/af_inet6.c:659
sock_recvmsg_nosec net/socket.c:944 [inline]
____sys_recvmsg+0x527/0x600 net/socket.c:2626
___sys_recvmsg+0x127/0x200 net/socket.c:2670
do_recvmmsg+0x24d/0x6d0 net/socket.c:2764
__sys_recvmmsg net/socket.c:2843 [inline]
__do_sys_recvmmsg net/socket.c:2866 [inline]
__se_sys_recvmmsg net/socket.c:2859 [inline]
__x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2859
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fc200d2dc39
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc5758e5a8 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc200d2dc39
RDX: 0000000000000002 RSI: 00000000200017c0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000f0b5ff
R10: 0000000000000100 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffc5758e5d0 R14: 00007ffc5758e5c0 R15: 0000000000000003
----------------
Code disassembly (best guess):
0: 38 00 cmp %al,(%rax)
2: 74 ed je 0xfffffff1
4: 48 8d 50 08 lea 0x8(%rax),%rdx
8: eb 09 jmp 0x13
a: 48 83 c0 01 add $0x1,%rax
e: 48 39 d0 cmp %rdx,%rax
11: 74 7a je 0x8d
13: 80 38 00 cmpb $0x0,(%rax)
16: 74 f2 je 0xa
18: 48 89 c2 mov %rax,%rdx
1b: b8 01 00 00 00 mov $0x1,%eax
20: 48 85 d2 test %rdx,%rdx
23: 75 56 jne 0x7b
25: 5b pop %rbx
26: 5d pop %rbp
27: 41 5c pop %r12
29: c3 retq
* 2a: 48 85 d2 test %rdx,%rdx <-- trapping instruction
2d: 74 5e je 0x8d
2f: 48 01 ea add %rbp,%rdx
32: eb 09 jmp 0x3d
34: 48 83 c0 01 add $0x1,%rax
38: 48 39 d0 cmp %rdx,%rax
3b: 74 50 je 0x8d
3d: 80 38 00 cmpb $0x0,(%rax)

---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

Next message: Josh Poimboeuf: "Re: CONFIG_ORC_UNWINDER=y breaks get_wchan()?"
Previous message: Sean Christopherson: "[PATCH v3 16/16] perf: Drop guest callback (un)register stubs"
Next in thread: Paolo Abeni: "Re: [syzbot] INFO: rcu detected stall in sys_recvmmsg"
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