Re: [PATCH v5 1/4] mm/page_alloc: only free healthy pages in high-order has_hwpoisoned folio

[Jiaqi Yan]

On Mon, Jun 22, 2026 at 8:32 AM Zi Yan <ziy@xxxxxxxxxx> wrote:
>
> On Mon Jun 22, 2026 at 11:20 AM EDT, Zi Yan wrote:
> > On Mon Jun 22, 2026 at 4:35 AM EDT, Vlastimil Babka (SUSE) wrote:
> >> On 6/22/26 03:13, Jiaqi Yan wrote:
> >>> On Thu, Jun 18, 2026 at 9:04 AM Zi Yan <ziy@xxxxxxxxxx> wrote:
> >>>> >> when copy fails with EHWPOISON), the next list_add() is going to cause
> >>>> >
> >>>> > I think we should fix compaction_free() (as a separate patch preceding this
> >>>> > one) to not proceed if prepare returns false. It could in theory already
> >>>> > happen before this patch due to a random memory corruption of struct page
> >>>> > causing some of the existing checks to fail.
> >>>>
> >>>> Something like below should do the job, plus
> >>>> Fixes: 733aea0b3a7bb ("mm/compaction: add support for >0 order folio memory compaction.")
> >>>>
> >>>> diff --git a/mm/compaction.c b/mm/compaction.c
> >>>> index b776f35ad0200..b2104cbe63477 100644
> >>>> --- a/mm/compaction.c
> >>>> +++ b/mm/compaction.c
> >>>> @@ -1876,10 +1876,12 @@ static void compaction_free(struct folio *dst, unsigned long data)
> >>>>         struct page *page = &dst->page;
> >>>>
> >>>>         if (folio_put_testzero(dst)) {
> >>>> -               free_pages_prepare(page, order);
> >>>> +               if (!free_pages_prepare(page, order))
> >>>
> >>> ... for other cases that free_pages_prepare() fails, this is
> >>> absolutely necessary for correctness. Do you mind sending it out for
> >>> formal review (I will be happy to help review).
> >>
> >> I think it would be faster if you just added it to your series with a
> >> Suggested-by: or something? Unless Zi objects. The change is straightforward.
> >
> > Let me send it as a hotfix separately, since Andrew prefers to have a
> > standalone hotfix to avoid splitting a series.
> >
> >>
> >> I'd perhaps do just a
> >>
> >> if (folio_put_testzero(dst) && free_pages_prepare(page, order))
> >>
> >> to avoid the goto?
> >
> > Will do.
> >>
> >>>> +                       goto skip;
> >>>>                 list_add(&dst->lru, &cc->freepages[order]);
> >>>>                 cc->nr_freepages += 1 << order;
> >>>>         }
> >>>> +skip:
> >>>>         cc->nr_migratepages += 1 << order;
> >>>>         /*
> >>>>          * someone else has referenced the page, we cannot take it back to our
> >>
> >> Maybe in the comment here add also the possibility that _prepare failed().
> >
> > Sure.
>
> Done.
>
> Link: https://lore.kernel.org/linux-mm/20260622-handle_free_pages_prepare_in_compaction_free-v1-1-fcf3b14abcf7@xxxxxxxxxx/

Thank you, Zi!

>
>
>
> --
> Best Regards,
> Yan, Zi
>