From: Alistair Popple <alistair@popple.id.au>
To: Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Andrew Morton" <akpm@linux-foundation.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Ralph Campbell" <rcampbell@nvidia.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 2/2] mm/rmap: Fixup copying of soft dirty and uffd ptes
Date: Tue, 25 Aug 2020 15:19:50 +1000 [thread overview]
Message-ID: <1650521.I2r5EI4MMx@cleo> (raw)
In-Reply-To: <20200824154359.GA8605@xz-x1>
On Tuesday, 25 August 2020 1:43:59 AM AEST Peter Xu wrote:
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -2427,9 +2427,11 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> >
> > entry = make_migration_entry(page, mpfn &
> >
> > MIGRATE_PFN_WRITE);
> >
> > swp_pte = swp_entry_to_pte(entry);
> >
> > - if (pte_soft_dirty(pte))
> > + if ((is_swap_pte(pte) && pte_swp_soft_dirty(pte))
> > + || (!is_swap_pte(pte) && pte_soft_dirty(pte)))
> >
> > swp_pte = pte_swp_mksoft_dirty(swp_pte);
> >
> > - if (pte_uffd_wp(pte))
> > + if ((is_swap_pte(pte) && pte_swp_uffd_wp(pte))
> > + || (!is_swap_pte(pte) && pte_uffd_wp(pte)))
> >
> > swp_pte = pte_swp_mkuffd_wp(swp_pte);
> >
> > set_pte_at(mm, addr, ptep, swp_pte);
>
> The worst case is we'll call is_swap_pte() four times for each entry. Also
> considering we know it's not a pte_none() when reach here, how about:
>
> if (pte_present(pte)) {
> // pte handling of both soft dirty and uffd-wp
> } else {
> // swap handling of both soft dirty and uffd-wp
> }
>
> ?
Works for me, I'd missed we knew it was not a pte_none() so will respin.
Thanks!
- Alistair
> Thanks,
next prev parent reply other threads:[~2020-08-25 5:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 8:31 [PATCH 1/2] mm/migrate: Fixup setting UFFD_WP flag Alistair Popple
2020-08-24 8:31 ` [PATCH 2/2] mm/rmap: Fixup copying of soft dirty and uffd ptes Alistair Popple
2020-08-24 15:43 ` Peter Xu
2020-08-25 5:19 ` Alistair Popple [this message]
2020-08-24 15:44 ` [PATCH 1/2] mm/migrate: Fixup setting UFFD_WP flag Peter Xu
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