Re: [PATCH] mm/debug_vm_pgtable: clear page table entries at destroy_args()

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 14 Aug 2025 16:16:03 +0530 Anshuman Khandual <anshuman.khandual@arm.com> wrote:

> On 01/08/25 3:10 AM, Herton R. Krzesinski wrote:
> > The mm/debug_vm_pagetable test allocates manually page table entries for the
> > tests it runs, using also its manually allocated mm_struct. That in itself is
> > ok, but when it exits, at destroy_args() it fails to clear those entries with
> > the *_clear functions.
> > 
> > The problem is that leaves stale entries. If another process allocates
> > an mm_struct with a pgd at the same address, it may end up running into
> > the stale entry. This is happening in practice on a debug kernel with
> > CONFIG_DEBUG_VM_PGTABLE=y, for example this is the output with some
> > extra debugging I added (it prints a warning trace if pgtables_bytes goes
> > negative, in addition to the warning at check_mm() function):
>
> This has been on linux-next for almost last two weeks now and
> no problem has been reported. So I guess it's all good.
> 

[top-posting repaired]

Thanks, I'll move this into the next batch for sending into mainline.