From: Vlastimil Babka <vbabka@suse.cz>
To: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org
Subject: Re: [PATCH 3/12] mm: page migration fix PageMlocked on migrated pages
Date: Thu, 5 Nov 2015 19:18:46 +0100 [thread overview]
Message-ID: <563B9D86.30608@suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.1510182150590.2481@eggly.anvils>
On 10/19/2015 06:52 AM, Hugh Dickins wrote:
> Commit e6c509f85455 ("mm: use clear_page_mlock() in page_remove_rmap()")
> in v3.7 inadvertently made mlock_migrate_page() impotent: page migration
> unmaps the page from userspace before migrating, and that commit clears
> PageMlocked on the final unmap, leaving mlock_migrate_page() with nothing
> to do. Not a serious bug, the next attempt at reclaiming the page would
> fix it up; but a betrayal of page migration's intent - the new page ought
> to emerge as PageMlocked.
>
> I don't see how to fix it for mlock_migrate_page() itself; but easily
> fixed in remove_migration_pte(), by calling mlock_vma_page() when the
> vma is VM_LOCKED - under pte lock as in try_to_unmap_one().
>
> Delete mlock_migrate_page()? Not quite, it does still serve a purpose
> for migrate_misplaced_transhuge_page(): where we could replace it by a
> test, clear_page_mlock(), mlock_vma_page() sequence; but would that be
> an improvement? mlock_migrate_page() is fairly lean, and let's make
> it leaner by skipping the irq save/restore now clearly not needed.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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next prev parent reply other threads:[~2015-11-05 18:18 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-19 4:44 [PATCH 0/12] mm: page migration cleanups, and a little mlock Hugh Dickins
2015-10-19 4:45 ` [PATCH 1/12] mm Documentation: undoc non-linear vmas Hugh Dickins
2015-10-19 9:16 ` Kirill A. Shutemov
2015-11-05 17:29 ` Vlastimil Babka
2015-10-19 4:50 ` [PATCH 2/12] mm: rmap use pte lock not mmap_sem to set PageMlocked Hugh Dickins
2015-10-19 6:23 ` Vlastimil Babka
2015-10-19 11:20 ` Hugh Dickins
2015-10-19 12:33 ` Vlastimil Babka
2015-10-19 19:17 ` Hugh Dickins
2015-10-19 20:52 ` Vlastimil Babka
2015-10-19 13:13 ` Kirill A. Shutemov
2015-10-19 19:53 ` Hugh Dickins
2015-10-19 20:10 ` Kirill A. Shutemov
2015-10-19 21:25 ` Vlastimil Babka
2015-10-19 21:53 ` Kirill A. Shutemov
2015-10-21 23:26 ` Hugh Dickins
2015-10-29 18:49 ` [PATCH v2 " Hugh Dickins
2015-11-05 17:50 ` Vlastimil Babka
2015-10-19 23:30 ` [PATCH " Davidlohr Bueso
2015-10-19 4:52 ` [PATCH 3/12] mm: page migration fix PageMlocked on migrated pages Hugh Dickins
2015-11-05 18:18 ` Vlastimil Babka [this message]
2015-10-19 4:54 ` [PATCH 4/12] mm: rename mem_cgroup_migrate to mem_cgroup_replace_page Hugh Dickins
2015-10-19 12:35 ` Johannes Weiner
2015-12-02 9:33 ` [PATCH] mm: fix kerneldoc on mem_cgroup_replace_page Hugh Dickins
2015-12-02 10:17 ` Michal Hocko
2015-12-02 16:57 ` Johannes Weiner
2015-10-19 4:55 ` [PATCH 5/12] mm: correct a couple of page migration comments Hugh Dickins
2015-10-21 17:53 ` Rafael Aquini
2015-10-19 4:57 ` [PATCH 6/12] mm: page migration use the put_new_page whenever necessary Hugh Dickins
2015-11-05 18:31 ` Vlastimil Babka
2015-11-08 21:17 ` Hugh Dickins
2015-10-19 4:59 ` [PATCH 7/12] mm: page migration trylock newpage at same level as oldpage Hugh Dickins
2015-10-21 17:54 ` Rafael Aquini
2015-10-19 5:01 ` [PATCH 8/12] mm: page migration remove_migration_ptes at lock+unlock level Hugh Dickins
2015-10-19 5:03 ` [PATCH 9/12] mm: simplify page migration's anon_vma comment and flow Hugh Dickins
2015-10-19 5:05 ` [PATCH 10/12] mm: page migration use migration entry for swapcache too Hugh Dickins
2015-10-22 22:35 ` Cyrill Gorcunov
2015-10-19 5:07 ` [PATCH 11/12] mm: page migration avoid touching newpage until no going back Hugh Dickins
2015-10-19 5:11 ` [PATCH 12/12] mm: migrate dirty page without clear_page_dirty_for_io etc Hugh Dickins
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