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

From: Linus Torvalds
Date: Fri Oct 23 2020 - 13:51:18 EST


On Fri, Oct 23, 2020 at 10:00 AM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
>
> [Old patch from yesterday]
>
> After applying your patch on top on linux next tag 20201015
> there are two observations,
> 1) i386 build failed. please find build error build

Yes, this was expected. That patch explicitly only works on x86-64,
because 32-bit needs the double register handling for 64-bit values
(mainly loff_t).

> 2) x86_64 kasan test PASS and the reported error not found.

Ok, good. That confirms that the problem you reported is indeed the
register allocation.

The patch I sent an hour ago (the one based on Rasmus' one from
yesterday) should fix things too, and - unlike yesterday's - work on
32-bit.

But I'll wait for confirmation (and hopefully a sign-off from Rasmus
so that I can give him authorship) before actually committing it.

Linus