Re: mmstress[1309]: segfault at 7f3d71a36ee8 ip 00007f3d77132bdf sp 00007f3d71a36ee8 error 4 in libc-2.27.so[7f3d77058000+1aa000]

[Naresh Kamboju]

On Wed, 21 Oct 2020 at 22:52, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
>
> On Wed, 21 Oct 2020 at 22:35, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Wed, Oct 21, 2020 at 9:58 AM Naresh Kamboju
> > <naresh.kamboju@xxxxxxxxxx> wrote:
> > >
> > > LTP mm mtest05 (mmstress), mtest06_3 and mallocstress01 (mallocstress) tested on
> > > x86 KASAN enabled build. But tests are getting PASS on Non KASAN builds.
> > > This regression started happening from next-20201015 nowards
> >
> > Is it repeatable enough to be bisectable?
>
> Yes. This is easily reproducible.
> I will bisect and report here.

The bad commit points to,

commit d55564cfc222326e944893eff0c4118353e349ec
x86: Make __put_user() generate an out-of-line call

I have reverted this single patch and confirmed the reported
problem is not seen anymore.

- Naresh