[PATCH v2] arm64/sve: Lower the maximum allocation for the SVE ptrace regset

[Doug Anderson]

Hi,

On Thu, Feb 15, 2024 at 4:44 AM Will Deacon <will at kernel.org> wrote:
>
> On Tue, 13 Feb 2024 18:24:38 +0000, Mark Brown wrote:
> > Doug Anderson observed that ChromeOS crashes are being reported which
> > include failing allocations of order 7 during core dumps due to ptrace
> > allocating storage for regsets:
> >
> >   chrome: page allocation failure: order:7,
> >           mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO),
> >           nodemask=(null),cpuset=urgent,mems_allowed=0
> >    ...
> >   regset_get_alloc+0x1c/0x28
> >   elf_core_dump+0x3d8/0xd8c
> >   do_coredump+0xeb8/0x1378
> >
> > [...]
>
> Applied to arm64 (for-next/fixes), thanks!
>
> [1/1] arm64/sve: Lower the maximum allocation for the SVE ptrace regset
>       https://git.kernel.org/arm64/c/2813926261e4

Thanks!

A side note to anyone trying to backport this is that there's a hidden
dependency of commit f171f9e4097d ("arm64/fp: Make SVE and SME length
register definition match architecture"). Without that dependency then
backporting ${SUBJECT} patch is just a no-op. ...backporting the
hidden dependency ends up giving merge conflicts, so for the purposes
of picking this to our 5.15 or earlier branches I went back to just
making the #define be 16 again like it was in v1.

-Doug