Re: INFO: task hung in request_key_tag
syzbot has found a reproducer for the following crash on:
HEAD commit:aab20039 Add linux-next specific files for 20200701
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14000a5b10
kernel config: https://syzkaller.appspot.com/x/.config?x=739f6fbf326049f4
dashboard link: https://syzkaller.appspot.com/bug?extid=46c77dc7e98c732de754
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=127e085b10
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=107ffaa710
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+46c77dc7e98c732de...@syzkaller.appspotmail.com
INFO: task syz-executor067:6800 blocked for more than 143 seconds.
Not tainted 5.8.0-rc3-next-20200701-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor067 D27632 6800 6794 0x4000
Call Trace:
context_switch kernel/sched/core.c:3445 [inline]
__schedule+0x8b4/0x1e80 kernel/sched/core.c:4169
schedule+0xd0/0x2a0 kernel/sched/core.c:4244
bit_wait+0x12/0xa0 kernel/sched/wait_bit.c:199
__wait_on_bit+0x60/0x190 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0xd5/0x110 kernel/sched/wait_bit.c:64
wait_on_bit include/linux/wait_bit.h:76 [inline]
wait_for_key_construction+0x10b/0x140 security/keys/request_key.c:664
request_key_tag+0x7a/0xb0 security/keys/request_key.c:705
dns_query+0x257/0x6c3 net/dns_resolver/dns_query.c:128
ceph_dns_resolve_name net/ceph/messenger.c:1887 [inline]
ceph_parse_server_name net/ceph/messenger.c:1922 [inline]
ceph_parse_ips+0x77f/0x8c0 net/ceph/messenger.c:1949
ceph_parse_mon_ips+0x59/0xc0 net/ceph/ceph_common.c:411
ceph_parse_source fs/ceph/super.c:271 [inline]
ceph_parse_mount_param+0x1239/0x17e0 fs/ceph/super.c:322
vfs_parse_fs_param fs/fs_context.c:117 [inline]
vfs_parse_fs_param+0x203/0x550 fs/fs_context.c:98
vfs_parse_fs_string+0xe6/0x150 fs/fs_context.c:161
do_new_mount fs/namespace.c:2905 [inline]
do_mount+0x1222/0x1df0 fs/namespace.c:3237
__do_sys_mount fs/namespace.c:3447 [inline]
__se_sys_mount fs/namespace.c:3424 [inline]
__x64_sys_mount+0x18f/0x230 fs/namespace.c:3424
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4401b9
Code: Bad RIP value.
RSP: 002b:7fff4cd307c8 EFLAGS: 0246 ORIG_RAX: 00a5
RAX: ffda RBX: 0030656c69662f2e RCX: 004401b9
RDX: 2040 RSI: 2080 RDI: 22c0
RBP: 006ca018 R08: R09:
R10: R11: 0246 R12: 00401a40
R13: 00401ad0 R14: R15:
Showing all locks held in the system:
1 lock held by khungtaskd/1146:
#0: 89bc3000 (rcu_read_lock){}-{1:2}, at:
debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
1 lock held by in:imklog/6692:
#0: 88809a086af0 (>f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100
fs/file.c:928
=
NMI backtrace for cpu 0
CPU: 0 PID: 1146 Comm: khungtaskd Not tainted 5.8.0-rc3-next-20200701-syzkaller
#0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
watchdog+0xd89/0xf30 kernel/hung_task.c:339
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3852 Comm: systemd-journal Not tainted
5.8.0-rc3-next-20200701-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
01/01/2011
RIP: 0010:pmd_none arch/x86/include/asm/pgtable.h:825 [inline]
RIP: 0010:pmd_none_or_trans_huge_or_clear_bad include/linux/pgtable.h:1198
[inline]
RIP: 0010:pmd_trans_unstable include/linux/pgtable.h:1223 [inline]
RIP: 0010:pmd_devmap_trans_unstable mm/memory.c:3496 [inline]
RIP: 0010:pmd_devmap_trans_unstable mm/memory.c:3494 [inline]
RIP: 0010:handle_pte_fault mm/memory.c:4198 [inline]
RIP: 0010:__handle_mm_fault mm/memory.c:4360 [inline]
RIP: 0010:handle_mm_fault+0x1da0/0x43f0 mm/memory.c:4397
Code: ff e9 9d f3 ff ff e8 0f 93 cf ff 48 89 ea 48 b8 00 00 00 00 00 fc ff df
48 c1 ea 03 80 3c 02 00 0f 85 b9 20 00 00 4c 8b 65 00 <4c> 89 e3 31 ff 48 83 e3
9f 48 89 de e8 7f 8f cf ff 48 85 db 0f 84
RSP: :c900015d7d70 EFLAGS: 0246
RAX: dc00 RBX: RCX: 81a44fec
RDX: 111012ad8f4a RSI: 81a45861 RDI: 0007
RBP: 8880956c7a50 R08: R09:
Re: INFO: task hung in request_key_tag
On 2020/07/01 21:20, Luis Chamberlain wrote:
> On Wed, Jul 01, 2020 at 07:04:15PM +0900, Tetsuo Handa wrote:
>> I suspect commit 9e9b47d6bbe9df65 ("umh: fix processed error when
>> UMH_WAIT_PROC is used").
>> Maybe the change in kernel/umh.c and/or security/keys/request_key.c made by
>> that commit is
>> affecting call_usermodehelper_keys() == 0 case when complete_request_key()
>> is called.
>
> That patch has been dropped for now due to another reported issue
> bisected to it and even though we have not root caused that issue [0].
>
> It would be good to have a reproducer for this reported issue as well,
Reproducer is not available yet.
But at least this patch is changing the behavior of
call_usermodehelper_keys() == 0 && (test_bit(KEY_FLAG_USER_CONSTRUCT,
>flags) || key_validate(key) < 0)
case from key_negate_and_link() to key_revoke() in complete_request_key().
Since test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, >flags) might be called
from
key_reject_and_link() from key_negate_and_link(), this change might be the
cause of
this hung task report.
Re: INFO: task hung in request_key_tag
On Wed, Jul 01, 2020 at 07:04:15PM +0900, Tetsuo Handa wrote:
> I suspect commit 9e9b47d6bbe9df65 ("umh: fix processed error when
> UMH_WAIT_PROC is used").
> Maybe the change in kernel/umh.c and/or security/keys/request_key.c made by
> that commit is
> affecting call_usermodehelper_keys() == 0 case when complete_request_key() is
> called.
That patch has been dropped for now due to another reported issue
bisected to it and even though we have not root caused that issue [0].
It would be good to have a reproducer for this reported issue as well,
but I should also point out a regression which Naresh reported is fixed
recently by a posted patch [1] by Herbert Xu. It would be good if you
can test with that patch posted by Herbert.
[0] https://lkml.kernel.org/r/20200623141157.5409-1-borntrae...@de.ibm.com
[1] https://lkml.kernel.org/r/20200626062948.ga25...@gondor.apana.org.au
Luis
>
> On 2020/07/01 16:53, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:c28e58ee Add linux-next specific files for 20200629
> > git tree: linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17925a9d10
> > kernel config: https://syzkaller.appspot.com/x/.config?x=dcd26bbca17dd1db
> > dashboard link: https://syzkaller.appspot.com/bug?extid=46c77dc7e98c732de754
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> >
> > 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+46c77dc7e98c732de...@syzkaller.appspotmail.com
Re: INFO: task hung in request_key_tag
I suspect commit 9e9b47d6bbe9df65 ("umh: fix processed error when UMH_WAIT_PROC
is used").
Maybe the change in kernel/umh.c and/or security/keys/request_key.c made by
that commit is
affecting call_usermodehelper_keys() == 0 case when complete_request_key() is
called.
On 2020/07/01 16:53, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:c28e58ee Add linux-next specific files for 20200629
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17925a9d10
> kernel config: https://syzkaller.appspot.com/x/.config?x=dcd26bbca17dd1db
> dashboard link: https://syzkaller.appspot.com/bug?extid=46c77dc7e98c732de754
> compiler: gcc (GCC) 10.1.0-syz 20200507
>
> 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+46c77dc7e98c732de...@syzkaller.appspotmail.com
