Re: [PATCH v5 2/2] mm/memory-failure: teach kill_accessing_process to accept hugetlb tail page pfn

[jane . chu]

On 1/14/2026 11:36 PM, Miaohe Lin wrote:
> On 2026/1/15 5:37, Jane Chu wrote:
> > When a hugetlb folio is being poisoned again, try_memory_failure_hugetlb()
> > passed head pfn to kill_accessing_process(), that is not right.
> > The precise pfn of the poisoned page should be used in order to
> > determine the precise vaddr as the SIGBUS payload.
> >
> > This issue has already been taken care of in the normal path, that is,
> > hwpoison_user_mappings(), see [1][2].  Further more, for [3] to work
> > correctly in the hugetlb repoisoning case, it's essential to inform
> > VM the precise poisoned page, not the head page.
> >
> > [1] https://lkml.kernel.org/r/20231218135837.3310403-1-willy@xxxxxxxxxxxxx
> > [2] https://lkml.kernel.org/r/20250224211445.2663312-1-jane.chu@xxxxxxxxxx
> > [3] https://lore.kernel.org/lkml/20251116013223.1557158-1-jiaqiyan@xxxxxxxxxx/
> >
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
> > Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > ---
> > v5, v4: No change.
> > v2 -> v3:
> >    incorporated suggestions from Miaohe and Matthew.
> > v1 -> v2:
> >    pickup R-B, add stable to cc list.
> > ---
> >   mm/memory-failure.c | 14 ++++++++------
> >   1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index 2563718c34c6..f6b806499caa 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -692,6 +692,8 @@ static int check_hwpoisoned_entry(pte_t pte, unsigned long addr, short shift,
> >   				unsigned long poisoned_pfn, struct to_kill *tk)
> >   {
> >   	unsigned long pfn = 0;
> > +	unsigned long hwpoison_vaddr;
> > +	unsigned long mask;
> >   
> >   	if (pte_present(pte)) {
> >   		pfn = pte_pfn(pte);
> > @@ -702,10 +704,12 @@ static int check_hwpoisoned_entry(pte_t pte, unsigned long addr, short shift,
> >   			pfn = softleaf_to_pfn(entry);
> >   	}
> >   
> > -	if (!pfn || pfn != poisoned_pfn)
> > +	mask = ~((1UL << (shift - PAGE_SHIFT)) - 1);
> > +	if (!pfn || ((pfn & mask) != (poisoned_pfn & mask)))
> >   		return 0;
>
> Nit: Maybe "(!pfn || pfn != (poisoned_pfn & mask))" is enough?

That's nicer.

> Acked-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>

Thanks!
-jane

> Thanks.
> .