Re: [PATCH] selftests/mm: fix size truncation in pagemap_ioctl test

[Zenghui Yu <zenghui.yu@linux.dev>]

On 9/7/26 11:22 PM, David Hildenbrand (Arm) wrote:
> On 9/7/26 15:56, Zenghui Yu wrote:
> > From: "Zenghui Yu (Huawei)" <zenghui.yu@linux.dev>
> >
> > On arm64 with 64K base pages, the huge page size is 512 MiB, and
> > hpage_unit_tests() builds a 5 GiB range (10 * 512 MiB) for its tests.  This
> > exceeds the range of the int size parameters of gethugepage(),
> > wp_addr_range() and pagemap_ioctl().  The implicit truncation to 1 GiB
> > makes gethugepage() allocate a too small buffer, while the callers keep
> > operating on the original 5 GiB range, resulting in spurious failures or
> > SIGSEGV.
> >
> > Change those size parameters to size_t.
> >
> > Fixes: 46fd75d4a3c9 ("selftests: mm: add pagemap ioctl tests")
> > Assisted-by: GLM-5.3 OpenCode
> > Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
> > ---
> 
> Looking at pagemap_ioctl.c ... I think most functions should actually be "static".

Yup.

> Using size_t is ok. But then we should also change "unsigned long long mem_size"
> to size_t, no?
> 
> Also, in wp_free() we are suddenly using "long size". In pagemap_ioc() we're
> also still using "int len".
> 
> Can we consistently use one type please?

Yes we can.  This patch adopts a minimal fix for this specific issue.  I'll
unify all size-related parameters and variables to size_t in v2.

Thanks,
Zenghui