WARN in do_rt_tgsigqueueinfo()

WARN in do_rt_tgsigqueueinfo()

[Peter Zijlstra]

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Hi Thomas, Oleg,


trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap

[watchdog] kernel became tainted! (512/0) Last seed was 4072360471

[15908.562512] ------------[ cut here ]------------
[15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
[15908.577715] Modules linked in:
[15908.580857] CPU: 22 PID: 3312 Comm: trinity-c198 Not tainted 3.15.0-rc5-01700-g505011124ad0-dirty #1070
[15908.590412] Hardware name: Supermicro X8DTN/X8DTN, BIOS 4.6.3 01/08/2010
[15908.597228]  0000000000000009 ffff880428715e40 ffffffff81682052 0000000000000000
[15908.604834]  ffff880428715e78 ffffffff8109808c 0000000000000001 000000000000ffff
[15908.612402]  00000000efdcefbf 00000000efdcefbf 0000000000000129 ffff880428715e88
[15908.619941] Call Trace:
[15908.622423]  [<ffffffff81682052>] dump_stack+0x4e/0x7a
[15908.627600]  [<ffffffff8109808c>] warn_slowpath_common+0x8c/0xc0
[15908.633658]  [<ffffffff810980da>] warn_slowpath_null+0x1a/0x20
[15908.639535]  [<ffffffff810a9914>] do_rt_tgsigqueueinfo+0xb4/0xc0
[15908.645591]  [<ffffffff810a99f1>] SYSC_rt_tgsigqueueinfo+0x61/0x80
[15908.651851]  [<ffffffff810abb2e>] SyS_rt_tgsigqueueinfo+0xe/0x10
[15908.657946]  [<ffffffff8168a842>] system_call_fastpath+0x16/0x1b
[15908.664036] ---[ end trace 02450728e2526283 ]---


This is apparently a very common thing to hit according to google.

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Re: WARN in do_rt_tgsigqueueinfo()

[Mateusz Guzik]

On Thu, May 15, 2014 at 03:38:34PM +0200, Peter Zijlstra wrote:
> Hi Thomas, Oleg,
> 
> 
> trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap
> 
> [watchdog] kernel became tainted! (512/0) Last seed was 4072360471
> 
> [15908.562512] ------------[ cut here ]------------
> [15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
> [15908.577715] Modules linked in:
> [15908.580857] CPU: 22 PID: 3312 Comm: trinity-c198 Not tainted 3.15.0-rc5-01700-g505011124ad0-dirty #1070
> [15908.590412] Hardware name: Supermicro X8DTN/X8DTN, BIOS 4.6.3 01/08/2010
> [15908.597228]  0000000000000009 ffff880428715e40 ffffffff81682052 0000000000000000
> [15908.604834]  ffff880428715e78 ffffffff8109808c 0000000000000001 000000000000ffff
> [15908.612402]  00000000efdcefbf 00000000efdcefbf 0000000000000129 ffff880428715e88
> [15908.619941] Call Trace:
> [15908.622423]  [<ffffffff81682052>] dump_stack+0x4e/0x7a
> [15908.627600]  [<ffffffff8109808c>] warn_slowpath_common+0x8c/0xc0
> [15908.633658]  [<ffffffff810980da>] warn_slowpath_null+0x1a/0x20
> [15908.639535]  [<ffffffff810a9914>] do_rt_tgsigqueueinfo+0xb4/0xc0
> [15908.645591]  [<ffffffff810a99f1>] SYSC_rt_tgsigqueueinfo+0x61/0x80
> [15908.651851]  [<ffffffff810abb2e>] SyS_rt_tgsigqueueinfo+0xe/0x10
> [15908.657946]  [<ffffffff8168a842>] system_call_fastpath+0x16/0x1b
> [15908.664036] ---[ end trace 02450728e2526283 ]---
> 
> 
> This is apparently a very common thing to hit according to google.

Well, it warns about an argument received from userland, so nothing fishy
going on as far as kernel consistency is concerned if that's what you mean.

-- 
Mateusz Guzik

Re: WARN in do_rt_tgsigqueueinfo()

[Peter Zijlstra]

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On Thu, May 15, 2014 at 04:27:24PM +0200, Mateusz Guzik wrote:
> On Thu, May 15, 2014 at 03:38:34PM +0200, Peter Zijlstra wrote:
> > Hi Thomas, Oleg,
> > 
> > 
> > trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap
> > 
> > [watchdog] kernel became tainted! (512/0) Last seed was 4072360471
> > 
> > [15908.562512] ------------[ cut here ]------------
> > [15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
> > [15908.577715] Modules linked in:
> > [15908.580857] CPU: 22 PID: 3312 Comm: trinity-c198 Not tainted 3.15.0-rc5-01700-g505011124ad0-dirty #1070
> > [15908.590412] Hardware name: Supermicro X8DTN/X8DTN, BIOS 4.6.3 01/08/2010
> > [15908.597228]  0000000000000009 ffff880428715e40 ffffffff81682052 0000000000000000
> > [15908.604834]  ffff880428715e78 ffffffff8109808c 0000000000000001 000000000000ffff
> > [15908.612402]  00000000efdcefbf 00000000efdcefbf 0000000000000129 ffff880428715e88
> > [15908.619941] Call Trace:
> > [15908.622423]  [<ffffffff81682052>] dump_stack+0x4e/0x7a
> > [15908.627600]  [<ffffffff8109808c>] warn_slowpath_common+0x8c/0xc0
> > [15908.633658]  [<ffffffff810980da>] warn_slowpath_null+0x1a/0x20
> > [15908.639535]  [<ffffffff810a9914>] do_rt_tgsigqueueinfo+0xb4/0xc0
> > [15908.645591]  [<ffffffff810a99f1>] SYSC_rt_tgsigqueueinfo+0x61/0x80
> > [15908.651851]  [<ffffffff810abb2e>] SyS_rt_tgsigqueueinfo+0xe/0x10
> > [15908.657946]  [<ffffffff8168a842>] system_call_fastpath+0x16/0x1b
> > [15908.664036] ---[ end trace 02450728e2526283 ]---
> > 
> > 
> > This is apparently a very common thing to hit according to google.
> 
> Well, it warns about an argument received from userland, so nothing fishy
> going on as far as kernel consistency is concerned if that's what you mean.

I hadn't looked that far.. I just manged to hit it two times in a row
while waiting for my bug to trigger.

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Re: WARN in do_rt_tgsigqueueinfo()

[Dave Jones]

On Thu, May 15, 2014 at 05:04:12PM +0200, Peter Zijlstra wrote:

 > > > trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap
 > > > 
 > > > [watchdog] kernel became tainted! (512/0) Last seed was 4072360471
 > > > 
 > > > [15908.562512] ------------[ cut here ]------------
 > > > [15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
 > > > 
 > > > This is apparently a very common thing to hit according to google.
 > > 
 > > Well, it warns about an argument received from userland, so nothing fishy
 > > going on as far as kernel consistency is concerned if that's what you mean.
 > 
 > I hadn't looked that far.. I just manged to hit it two times in a row
 > while waiting for my bug to trigger.

There's a ton of 'noise' like this that fuzzing turns up.
I've been collecting some of the stuff to shut it up..

http://codemonkey.org.uk/junk/silence-fuzz-testing-noise.patch
http://codemonkey.org.uk/junk/silence-noisy-deprecated-warnings-while-fuzzing.patch

I'm of the opinion that a user-triggerable WARN is a bug, but aparently
not everyone else feels that way.

	Dave

Re: WARN in do_rt_tgsigqueueinfo()

[Peter Zijlstra]

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On Thu, May 15, 2014 at 11:54:15AM -0400, Dave Jones wrote:
> There's a ton of 'noise' like this that fuzzing turns up.
> I've been collecting some of the stuff to shut it up..
> 
> http://codemonkey.org.uk/junk/silence-fuzz-testing-noise.patch
> http://codemonkey.org.uk/junk/silence-noisy-deprecated-warnings-while-fuzzing.patch
> 
> I'm of the opinion that a user-triggerable WARN is a bug, but aparently
> not everyone else feels that way.

Awesome, thanks!

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Re: WARN in do_rt_tgsigqueueinfo()

[Mateusz Guzik]

On Thu, May 15, 2014 at 11:54:15AM -0400, Dave Jones wrote:
> On Thu, May 15, 2014 at 05:04:12PM +0200, Peter Zijlstra wrote:
> 
>  > > > trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap
>  > > > 
>  > > > [watchdog] kernel became tainted! (512/0) Last seed was 4072360471
>  > > > 
>  > > > [15908.562512] ------------[ cut here ]------------
>  > > > [15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
>  > > > 
>  > > > This is apparently a very common thing to hit according to google.
>  > > 
>  > > Well, it warns about an argument received from userland, so nothing fishy
>  > > going on as far as kernel consistency is concerned if that's what you mean.
>  > 
>  > I hadn't looked that far.. I just manged to hit it two times in a row
>  > while waiting for my bug to trigger.
> 
> There's a ton of 'noise' like this that fuzzing turns up.
> I've been collecting some of the stuff to shut it up..
> 
> http://codemonkey.org.uk/junk/silence-fuzz-testing-noise.patch
> http://codemonkey.org.uk/junk/silence-noisy-deprecated-warnings-while-fuzzing.patch
> 
> I'm of the opinion that a user-triggerable WARN is a bug, but aparently
> not everyone else feels that way.
> 

imho warning sysadmins about userspace using deprecated stuff is fine as
long as users are not able to spam the console with it.

Warning reported here just looks scary and provides no information for
sysadmins so I guess it hould be changed.

I see no value in removing this stuff. If it shows up in production you
most likely want to know. Filtering this out during fuzzing should be an
issue.

my $0,03
-- 
Mateusz Guzik

Re: WARN in do_rt_tgsigqueueinfo()

[Thomas Gleixner]

On Thu, 15 May 2014, Dave Jones wrote:

> On Thu, May 15, 2014 at 05:04:12PM +0200, Peter Zijlstra wrote:
> 
>  > > > trinity$ MALLOC_CHECK_=0 ./trinity -xinit_module -xreboot -xshutdown -xunshare -xnfsservctl -xclock_nanosleep -xuselib -xumount -xmount -m --quiet -C 400 -l off -xmremap
>  > > > 
>  > > > [watchdog] kernel became tainted! (512/0) Last seed was 4072360471
>  > > > 
>  > > > [15908.562512] ------------[ cut here ]------------
>  > > > [15908.567245] WARNING: CPU: 22 PID: 3312 at /usr/src/linux-2.6/kernel/signal.c:3060 do_rt_tgsigqueueinfo+0xb4/0xc0()
>  > > > 
>  > > > This is apparently a very common thing to hit according to google.
>  > > 
>  > > Well, it warns about an argument received from userland, so nothing fishy
>  > > going on as far as kernel consistency is concerned if that's what you mean.
>  > 
>  > I hadn't looked that far.. I just manged to hit it two times in a row
>  > while waiting for my bug to trigger.
> 
> There's a ton of 'noise' like this that fuzzing turns up.
> I've been collecting some of the stuff to shut it up..
> 
> http://codemonkey.org.uk/junk/silence-fuzz-testing-noise.patch
> http://codemonkey.org.uk/junk/silence-noisy-deprecated-warnings-while-fuzzing.patch
> 
> I'm of the opinion that a user-triggerable WARN is a bug, but aparently
> not everyone else feels that way.

I agree. It returns -EPERM which is the right answer

Thanks,

	tglx

Re: WARN in do_rt_tgsigqueueinfo()

[Oleg Nesterov]

On 05/15, Mateusz Guzik wrote:
>
> On Thu, May 15, 2014 at 11:54:15AM -0400, Dave Jones wrote:
> >
> > I'm of the opinion that a user-triggerable WARN is a bug, but aparently
> > not everyone else feels that way.

I didn't really like this WARN_ONCE() when I looked at the patch which
added it, but I didn't try to argue.

> imho warning sysadmins about userspace using deprecated stuff is fine as
> long as users are not able to spam the console with it.

Agreed,

> Warning reported here just looks scary and provides no information for
> sysadmins so I guess it hould be changed.

Again, agreed.

So imo we should either remove it, ot turn it into

	pr_warn_once("something meaningful");

Oleg.