Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-20 Thread Johnny Hughes
On 09/20/2017 03:10 AM, Pasi Kärkkäinen wrote:
> On Tue, Sep 05, 2017 at 10:49:13AM -0700, Nathan March wrote:
 I have no issues rolling this patch in , while we wait on upstream, if
 it makes our tree more stable.

>>>
>>> I think we should do that.. What do others think?
>>>
>>
>> I've had the patch deployed to a group of 32 hosts (with hundreds of vms)
>> for about 10 days now and no sign of any issues.
>>
>> So I support it =)
>>
> 
> Thanks Nathan.
> 
> Johnny: Can you please add the patch to next Linux 4.9 kernel build? 
> 
> 
> Thanks,
> 
> -- Pasi
> 
>> Cheers,
>> Nathan
> 
> 

It has already been built into the latest test kernel .. 4.9.48-29.el7




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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-20 Thread Pasi Kärkkäinen
On Tue, Sep 05, 2017 at 10:49:13AM -0700, Nathan March wrote:
> > > I have no issues rolling this patch in , while we wait on upstream, if
> > > it makes our tree more stable.
> > >
> > 
> > I think we should do that.. What do others think?
> > 
> 
> I've had the patch deployed to a group of 32 hosts (with hundreds of vms)
> for about 10 days now and no sign of any issues.
> 
> So I support it =)
> 

Thanks Nathan.

Johnny: Can you please add the patch to next Linux 4.9 kernel build? 


Thanks,

-- Pasi

> Cheers,
> Nathan

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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-05 Thread Nathan March
> > I have no issues rolling this patch in , while we wait on upstream, if
> > it makes our tree more stable.
> >
> 
> I think we should do that.. What do others think?
> 

I've had the patch deployed to a group of 32 hosts (with hundreds of vms)
for about 10 days now and no sign of any issues.

So I support it =)

Cheers,
Nathan

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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-03 Thread Pasi Kärkkäinen
On Sat, Sep 02, 2017 at 08:12:53AM -0500, Johnny Hughes wrote:
> On 08/30/2017 03:10 PM, Pasi Kärkkäinen wrote:
> > Hello everyone,
> > 
> > Recently Nathan March reported on centos-virt list he's getting frequent 
> > Linux kernel crashes with Linux 4.9 LTS kernel because of the missing patch 
> > "tty: Fix ldisc crash on reopened tty".
> > 
> > The patch was already merged upstream here:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71472fa9c52b1da27663c275d416d8654b905f05
> > 
> > but then reverted here:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=896d81fefe5d1919537db2c2150ab6384e4a6610
> > 
> > Nathan confirmed if he applies the patch from 
> > 71472fa9c52b1da27663c275d416d8654b905f05 to his Linux 4.9 LTS kernel the 
> > bug/problem goes away, so the patch (or similar fix) is still needed, at 
> > least for 4.9 LTS kernel.
> > 
> > 
> > Mikulas reported he's able to trigger the same crash on Linux 4.10:
> > https://www.spinics.net/lists/kernel/msg2440637.html
> > https://lists.gt.net/linux/kernel/2664604?search_string=ldisc%20reopened;#2664604
> > 
> > Michael Neuling reported he's able to trigger the bug on PowerPC:
> > https://lkml.org/lkml/2017/3/10/1582
> > 
> > 
> > So now the question is.. is anyone currently working on getting this patch 
> > fixed and applied upstream? I think one of the problems earlier was being 
> > able to reliable reproduce the crash.. Nathan says he's able to reproduce 
> > it many times per week on his environment on x86_64.
> > 
> 
> I have no issues rolling this patch in , while we wait on upstream, if
> it makes our tree more stable.
> 

I think we should do that.. What do others think?


Thanks,

-- Pasi

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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-02 Thread Johnny Hughes
On 08/30/2017 03:10 PM, Pasi Kärkkäinen wrote:
> Hello everyone,
> 
> Recently Nathan March reported on centos-virt list he's getting frequent 
> Linux kernel crashes with Linux 4.9 LTS kernel because of the missing patch 
> "tty: Fix ldisc crash on reopened tty".
> 
> The patch was already merged upstream here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71472fa9c52b1da27663c275d416d8654b905f05
> 
> but then reverted here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=896d81fefe5d1919537db2c2150ab6384e4a6610
> 
> Nathan confirmed if he applies the patch from 
> 71472fa9c52b1da27663c275d416d8654b905f05 to his Linux 4.9 LTS kernel the 
> bug/problem goes away, so the patch (or similar fix) is still needed, at 
> least for 4.9 LTS kernel.
> 
> 
> Mikulas reported he's able to trigger the same crash on Linux 4.10:
> https://www.spinics.net/lists/kernel/msg2440637.html
> https://lists.gt.net/linux/kernel/2664604?search_string=ldisc%20reopened;#2664604
> 
> Michael Neuling reported he's able to trigger the bug on PowerPC:
> https://lkml.org/lkml/2017/3/10/1582
> 
> 
> So now the question is.. is anyone currently working on getting this patch 
> fixed and applied upstream? I think one of the problems earlier was being 
> able to reliable reproduce the crash.. Nathan says he's able to reproduce it 
> many times per week on his environment on x86_64.
> 

I have no issues rolling this patch in , while we wait on upstream, if
it makes our tree more stable.




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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-09-01 Thread Pasi Kärkkäinen
On Thu, Aug 31, 2017 at 03:22:05PM +1000, Michael Neuling wrote:
> On Thu, 2017-08-31 at 06:36 +0200, Greg Kroah-Hartman wrote:
> > On Wed, Aug 30, 2017 at 11:10:14PM +0300, Pasi Kärkkäinen wrote:
> > > Hello everyone,
> > > 
> > > Recently Nathan March reported on centos-virt list he's getting frequent
> > > Linux kernel crashes with Linux 4.9 LTS kernel because of the missing 
> > > patch
> > > "tty: Fix ldisc crash on reopened tty".
> > 
> > Crashes with "normal" operation, or crashes when running a fuzzer or
> > other type of program?
> 
> For me it crashed on boot.
>

Nathan said he's getting the crashes at runtime, randomly, but often.

 
> > 
> > > The patch was already merged upstream here:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i
> > > d=71472fa9c52b1da27663c275d416d8654b905f05
> > > 
> > > but then reverted here:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i
> > > d=896d81fefe5d1919537db2c2150ab6384e4a6610
> > > 
> > > Nathan confirmed if he applies the patch from
> > > 71472fa9c52b1da27663c275d416d8654b905f05 to his Linux 4.9 LTS kernel the
> > > bug/problem goes away, so the patch (or similar fix) is still needed, at
> > > least for 4.9 LTS kernel.
> > > 
> > > 
> > > Mikulas reported he's able to trigger the same crash on Linux 4.10:
> > > https://www.spinics.net/lists/kernel/msg2440637.html
> > > https://lists.gt.net/linux/kernel/2664604?search_string=ldisc%20reopened;#26
> > > 64604
> > > 
> > > Michael Neuling reported he's able to trigger the bug on PowerPC:
> > > https://lkml.org/lkml/2017/3/10/1582
> > > 
> > > 
> > > So now the question is.. is anyone currently working on getting this patch
> > > fixed and applied upstream? I think one of the problems earlier was being
> > > able to reliable reproduce the crash.. Nathan says he's able to reproduce 
> > > it
> > > many times per week on his environment on x86_64.
> > 
> > I don't know of anyone working on it, want to do it yourself?
> 
> I'm not anymore. We found it was only triggered on a bogus CONFIG option
> combination.  Once we removed that, it no longer happened.
> 
> The underlying bug was still there though.
> 


Yep.. and the bug seems to trigger at runtime.



> Mikey


-- Pasi

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Re: [CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-08-30 Thread Kevin Stange
On 08/30/2017 03:10 PM, Pasi Kärkkäinen wrote:
> Hello everyone,
> 
> Recently Nathan March reported on centos-virt list he's getting frequent 
> Linux kernel crashes with Linux 4.9 LTS kernel because of the missing patch 
> "tty: Fix ldisc crash on reopened tty".
> 
> The patch was already merged upstream here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71472fa9c52b1da27663c275d416d8654b905f05
> 
> but then reverted here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=896d81fefe5d1919537db2c2150ab6384e4a6610
> 
> Nathan confirmed if he applies the patch from 
> 71472fa9c52b1da27663c275d416d8654b905f05 to his Linux 4.9 LTS kernel the 
> bug/problem goes away, so the patch (or similar fix) is still needed, at 
> least for 4.9 LTS kernel.
> 
> 
> Mikulas reported he's able to trigger the same crash on Linux 4.10:
> https://www.spinics.net/lists/kernel/msg2440637.html
> https://lists.gt.net/linux/kernel/2664604?search_string=ldisc%20reopened;#2664604
> 
> Michael Neuling reported he's able to trigger the bug on PowerPC:
> https://lkml.org/lkml/2017/3/10/1582
> 
> 
> So now the question is.. is anyone currently working on getting this patch 
> fixed and applied upstream? I think one of the problems earlier was being 
> able to reliable reproduce the crash.. Nathan says he's able to reproduce it 
> many times per week on his environment on x86_64.

I looked briefly at the patch and related discussion on the kernel
mailing lists and it seemed to be reverted not due to any problems it
caused with kernel behavior but rather due to concerns about
insufficient review before it was committed and possible merge conflicts.

The issue is the problem doesn't appear to have been discussed any
further on the kernel mailing lists since April, and I'm not sure why.
My inclination would be to start back up discussion upstream and try to
get clarification as to why the patch has remained reverted and there's
been no effort to bring it back into the kernel, rather than assume the
patch is safe to use.  I doubt anyone else but people experiencing the
issue have it up on their radar.

The 4.9 virt kernel does have some patches currently that haven't (yet)
been accepted upstream, so it's definitely an option to do that here.
As far as I know, nothing really gets pushed back upstream.  Most often
the patches are just plucked from upstream mailing lists before they get
merged into an official upstream release.

-- 
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Chief Technology Officer
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800 S Wells, Suite 190 | Chicago, IL 60607
312.602.2689 X203 | Fax: 312.602.2688
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[CentOS-virt] Status of reverted Linux patch "tty: Fix ldisc crash on reopened tty", Linux 4.9 kernel frequent crashes

2017-08-30 Thread Pasi Kärkkäinen
Hello everyone,

Recently Nathan March reported on centos-virt list he's getting frequent Linux 
kernel crashes with Linux 4.9 LTS kernel because of the missing patch "tty: Fix 
ldisc crash on reopened tty".

The patch was already merged upstream here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71472fa9c52b1da27663c275d416d8654b905f05

but then reverted here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=896d81fefe5d1919537db2c2150ab6384e4a6610

Nathan confirmed if he applies the patch from 
71472fa9c52b1da27663c275d416d8654b905f05 to his Linux 4.9 LTS kernel the 
bug/problem goes away, so the patch (or similar fix) is still needed, at least 
for 4.9 LTS kernel.


Mikulas reported he's able to trigger the same crash on Linux 4.10:
https://www.spinics.net/lists/kernel/msg2440637.html
https://lists.gt.net/linux/kernel/2664604?search_string=ldisc%20reopened;#2664604

Michael Neuling reported he's able to trigger the bug on PowerPC:
https://lkml.org/lkml/2017/3/10/1582


So now the question is.. is anyone currently working on getting this patch 
fixed and applied upstream? I think one of the problems earlier was being able 
to reliable reproduce the crash.. Nathan says he's able to reproduce it many 
times per week on his environment on x86_64.


Thanks a lot,

-- Pasi

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