WARNING in free_kthread_struct

[syzbot]

Hello,

syzkaller hit the following crash on
0f611fb6dcc0d6d91b4e1fec911321f434a3b858
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


WARNING: CPU: 0 PID: 4918 at kernel/kthread.c:87
free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4918 Comm: modprobe Not tainted 4.14.0-rc5-mm1+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:52
panic+0x1e4/0x41c kernel/panic.c:183
__warn+0x1c4/0x1e0 kernel/panic.c:546
report_bug+0x211/0x2d0 lib/bug.c:183
fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177
do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
do_trap+0x260/0x390 arch/x86/kernel/traps.c:260
do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
RSP: 0000:ffff8801db207768 EFLAGS: 00010206
RAX: ffff8801c431e680 RBX: ffff8801c548f400 RCX: ffffffff8148d7e2
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8801c548f4b8
RBP: ffff8801db207770 R08: 0000000000000001 R09: 1ffff1003b640edc
R10: ffff8801db2076a8 R11: 0000000000000004 R12: 1ffff1003b640ef0
R13: 1ffff1003b640ef4 R14: 0000000000000000 R15: ffff8801db2077e0
free_task+0x134/0x1a0 kernel/fork.c:390
__put_task_struct+0x229/0x3b0 kernel/fork.c:668
put_task_struct include/linux/sched/task.h:95 [inline]
delayed_put_task_struct+0xca/0x3d0 kernel/exit.c:180
__rcu_reclaim kernel/rcu/rcu.h:172 [inline]
rcu_do_batch kernel/rcu/tree.c:2676 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2897 [inline]
rcu_process_callbacks+0xd74/0x17d0 kernel/rcu/tree.c:2914
__do_softirq+0x2d7/0xb85 kernel/softirq.c:284
invoke_softirq kernel/softirq.c:364 [inline]
irq_exit+0x1cc/0x200 kernel/softirq.c:405
exiting_irq arch/x86/include/asm/apic.h:540 [inline]
smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052
apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:770
</IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:276 [inline]
RIP: 0010:compound_head include/linux/page-flags.h:146 [inline]
RIP: 0010:PageSwapBacked include/linux/page-flags.h:287 [inline]
RIP: 0010:mm_counter_file include/linux/mm.h:1522 [inline]
RIP: 0010:alloc_set_pte+0x71a/0x1880 mm/memory.c:3420
RSP: 0000:ffff8801c402f3e0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: ffff8801c402fb80 RCX: ffffffff81987189
RDX: 1ffff10038805e98 RSI: ffffea00076cb000 RDI: ffffea00076cb020
RBP: ffff8801c402f528 R08: 0000000000000001 R09: 1ffff10038805e0a
R10: ffff8801c402ef88 R11: 0000000000000003 R12: 1ffff10038805e84
R13: 1ffff10038805e98 R14: 0000000000000025 R15: ffffea00076cafe0
filemap_map_pages+0x1080/0x15d0 mm/filemap.c:2680
do_fault_around mm/memory.c:3567 [inline]
do_read_fault mm/memory.c:3601 [inline]
do_fault mm/memory.c:3706 [inline]
handle_pte_fault mm/memory.c:3936 [inline]
__handle_mm_fault+0x1f57/0x39c0 mm/memory.c:4060
handle_mm_fault+0x334/0x8d0 mm/memory.c:4097
__do_page_fault+0x5bd/0xd60 arch/x86/mm/fault.c:1438
do_page_fault+0xee/0x720 arch/x86/mm/fault.c:1514
page_fault+0x22/0x30 arch/x86/entry/entry_64.S:1066
RIP: 0033:0x7fe25f595390
RSP: 002b:00007ffeb59a5f08 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 00007ffeb59a72a8 RCX: 0000563871b59660
RDX: 00005638719547f0 RSI: 00007ffeb59a72a8 RDI: 0000000000000004
RBP: 00007ffeb59a72a8 R08: 00007ffeb59a5f7c R09: 0000000000000000
R10: 0000000000000000 R11: 00007fe25f595390 R12: 0000000000000004
R13: 0000563871954608 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Dmitry Vyukov]

On Tue, Nov 7, 2017 at 3:46 PM, syzbot
<bot+28a52b4b1430f7b2e8...@syzkaller.appspotmail.com>
wrote:

> Hello,
>
> syzkaller hit the following crash on
> 0f611fb6dcc0d6d91b4e1fec911321f434a3b858
> git://git.cmpxchg.org/linux-mmots.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers

This also happens on linux-next (e.g. on current HEAD
8b82a8a7ab53ee1a065ac69c835737a701f46b2e), but not on Linus tree.

Seems to be added by :

commit 05e3db95ebfc5c06a29a1d8c7a3e02f46f3a25a7
Author: Shaohua Li
Date: Thu Sep 14 14:02:04 2017 -0700
kthread: add a mechanism to store cgroup info

This severe hurts our testing, so far this crashed 133565 VMs.

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[Dmitry Vyukov]

Shaohua, please also follow this part:

\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

>> syzbot will keep track of this bug report.
>> Once a fix for this bug is committed, please reply to this email with:
>> #syz fix: exact-commit-title

This will greatly help to keep the whole process running and report
new bugs in future.

[Shaohua Li]

#syz fix: kthread: zero the kthread data structure

On 11/7/17, 6:55 AM, "Dmitry Vyukov" <dvy...@google.com> wrote:

On Tue, Nov 7, 2017 at 3:46 PM, syzbot
<bot+28a52b4b1430f7b2e8...@syzkaller.appspotmail.com>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> 0f611fb6dcc0d6d91b4e1fec911321f434a3b858
> git://git.cmpxchg.org/linux-mmots.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached

> syzkaller reproducer is attached. See https://urldefense.proofpoint.com/v2/url?u=https-3A__goo.gl_kgGztJ&d=DwIBaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=X13hAPkxmvBro1Ug8vcKHw&m=3z4_7peJuZLFfHagtSepRLz4PQM_pEXtHICbOkP4bBE&s=fQ3u9vQs9RX68GQ7tAtXyvYv9vJPPYPzaLPnlJQIzDA&e=

> See https://urldefense.proofpoint.com/v2/url?u=https-3A__goo.gl_tpsmEJ&d=DwIBaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=X13hAPkxmvBro1Ug8vcKHw&m=3z4_7peJuZLFfHagtSepRLz4PQM_pEXtHICbOkP4bBE&s=2EMzXVvFa3ly0nOmqGUIOPVqBS9WAqnJLEqJ1UQj0b4&e= for details.

> Direct all questions to syzk...@googlegroups.com.
> Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>
>
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
> Note: if the crash happens again, it will cause creation of a new bug
> report.
> Note: all commands must start from beginning of the line.
>
> --
> You received this message because you are subscribed to the Google Groups
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> To unsubscribe from this group and stop receiving emails from it, send an
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> To view this discussion on the web visit

> https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_msgid_syzkaller-2Dbugs_001a113ffe5a30836e055d65a1c5-2540google.com&d=DwIBaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=X13hAPkxmvBro1Ug8vcKHw&m=3z4_7peJuZLFfHagtSepRLz4PQM_pEXtHICbOkP4bBE&s=oq9MUe-iid1Snq-leL7l8BfP5YgVeR32bAlN_jMSpOQ&e=.
> For more options, visit https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwIBaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=X13hAPkxmvBro1Ug8vcKHw&m=3z4_7peJuZLFfHagtSepRLz4PQM_pEXtHICbOkP4bBE&s=2s0HG5KdaTES2MJrXV2FjjCjbY2sqwtwqTa_FhJSnWM&e=.