* Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree
[not found] ` <20190604145216.GJ4669@dhcp22.suse.cz>
@ 2019-06-04 15:07 ` Greg KH
2019-06-04 15:51 ` Ben Hutchings
0 siblings, 1 reply; 5+ messages in thread
From: Greg KH @ 2019-06-04 15:07 UTC (permalink / raw)
To: Michal Hocko
Cc: stable, aarcange, akpm, ben.hutchings, jannh, jgg, oleg, peterx,
rppt, torvalds, stable-commits
On Tue, Jun 04, 2019 at 04:52:31PM +0200, Michal Hocko wrote:
> Please note that I have posted my backport today
> http://lkml.kernel.org/r/20190604094953.26688-1-mhocko@kernel.org and it
> differs from this one. Please have a look!
Ah, good point, I just noticed that. Ben, any thoughts as to the
difference?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree
2019-06-04 15:07 ` Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree Greg KH
@ 2019-06-04 15:51 ` Ben Hutchings
2019-06-05 6:50 ` Michal Hocko
0 siblings, 1 reply; 5+ messages in thread
From: Ben Hutchings @ 2019-06-04 15:51 UTC (permalink / raw)
To: Greg KH, Michal Hocko
Cc: stable, aarcange, akpm, jannh, jgg, oleg, peterx, rppt, torvalds,
stable-commits
On Tue, 2019-06-04 at 17:07 +0200, Greg KH wrote:
> On Tue, Jun 04, 2019 at 04:52:31PM +0200, Michal Hocko wrote:
> > Please note that I have posted my backport today
> > http://lkml.kernel.org/r/20190604094953.26688-1-mhocko@kernel.org and it
> > differs from this one. Please have a look!
>
> Ah, good point, I just noticed that. Ben, any thoughts as to the
> difference?
- The additional fix in binder makes sense to me, and is also needed in
4.9. I'm not sure why I missed it.
- I don't understand why collapse_huge_range() needs to be fixed, but
then I really don't understand the khugepaged code at all! So I would
trust Michal on this.
- The userfaultfd fixes look different because I picked "userfaultfd:
don't pin the user memory in userfaultfd_file_create()" first and
Michal did not. I don't think it makes sense to be calling
mmget_still_valid() in these functions if they don't use
mmget_not_zero() or similar. But again, Michal is the expert here.
Ben.
--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree
2019-06-04 15:51 ` Ben Hutchings
@ 2019-06-05 6:50 ` Michal Hocko
2019-06-05 12:08 ` Ben Hutchings
0 siblings, 1 reply; 5+ messages in thread
From: Michal Hocko @ 2019-06-05 6:50 UTC (permalink / raw)
To: Ben Hutchings
Cc: Greg KH, stable, aarcange, akpm, jannh, jgg, oleg, peterx, rppt,
torvalds, stable-commits
On Tue 04-06-19 16:51:38, Ben Hutchings wrote:
[...]
> - I don't understand why collapse_huge_range() needs to be fixed, but
> then I really don't understand the khugepaged code at all! So I would
> trust Michal on this.
To be honest, I am not really sure myself here. But we are using a
remote mm there and I do not see anything that would prevent from racing
with exit/coredump. Maybe I am wrong. Let's wait for Andrea for his
review feedback. This patch is quite tricky for the stable backport.
Thanks!
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree
2019-06-05 6:50 ` Michal Hocko
@ 2019-06-05 12:08 ` Ben Hutchings
2019-06-06 15:34 ` Greg KH
0 siblings, 1 reply; 5+ messages in thread
From: Ben Hutchings @ 2019-06-05 12:08 UTC (permalink / raw)
To: Michal Hocko, Greg KH
Cc: stable, aarcange, akpm, jannh, jgg, oleg, peterx, rppt, torvalds,
stable-commits
On Wed, 2019-06-05 at 08:50 +0200, Michal Hocko wrote:
> On Tue 04-06-19 16:51:38, Ben Hutchings wrote:
> [...]
> > - I don't understand why collapse_huge_range() needs to be fixed, but
> > then I really don't understand the khugepaged code at all! So I would
> > trust Michal on this.
>
> To be honest, I am not really sure myself here. But we are using a
> remote mm there and I do not see anything that would prevent from racing
> with exit/coredump. Maybe I am wrong. Let's wait for Andrea for his
> review feedback. This patch is quite tricky for the stable backport.
So, Greg, it seems like you should drop this from the current stable
round.
Ben.
--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree
2019-06-05 12:08 ` Ben Hutchings
@ 2019-06-06 15:34 ` Greg KH
0 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2019-06-06 15:34 UTC (permalink / raw)
To: Ben Hutchings
Cc: Michal Hocko, stable, aarcange, akpm, jannh, jgg, oleg, peterx,
rppt, torvalds, stable-commits
On Wed, Jun 05, 2019 at 01:08:48PM +0100, Ben Hutchings wrote:
> On Wed, 2019-06-05 at 08:50 +0200, Michal Hocko wrote:
> > On Tue 04-06-19 16:51:38, Ben Hutchings wrote:
> > [...]
> > > - I don't understand why collapse_huge_range() needs to be fixed, but
> > > then I really don't understand the khugepaged code at all! So I would
> > > trust Michal on this.
> >
> > To be honest, I am not really sure myself here. But we are using a
> > remote mm there and I do not see anything that would prevent from racing
> > with exit/coredump. Maybe I am wrong. Let's wait for Andrea for his
> > review feedback. This patch is quite tricky for the stable backport.
>
> So, Greg, it seems like you should drop this from the current stable
> round.
Ok, will do, thanks.
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-06-06 15:34 UTC | newest]
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[not found] ` <20190604145216.GJ4669@dhcp22.suse.cz>
2019-06-04 15:07 ` Patch "coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping" has been added to the 4.4-stable tree Greg KH
2019-06-04 15:51 ` Ben Hutchings
2019-06-05 6:50 ` Michal Hocko
2019-06-05 12:08 ` Ben Hutchings
2019-06-06 15:34 ` Greg KH
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