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SubjectRe: [PATCH 2/6] mm: differentiate unmap for vmscan from other unmap.
On Sun, Jun 29, 2014 at 08:58:17PM -0700, John Hubbard wrote:
> On Fri, 27 Jun 2014, Jérôme Glisse wrote:
>
> > From: Jérôme Glisse <jglisse@redhat.com>
> >
> > New code will need to be able to differentiate between a regular unmap and
> > an unmap trigger by vmscan in which case we want to be as quick as possible.
> >
> > Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
> > ---
> > include/linux/rmap.h | 15 ++++++++-------
> > mm/memory-failure.c | 2 +-
> > mm/vmscan.c | 4 ++--
> > 3 files changed, 11 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> > index be57450..eddbc07 100644
> > --- a/include/linux/rmap.h
> > +++ b/include/linux/rmap.h
> > @@ -72,13 +72,14 @@ struct anon_vma_chain {
> > };
> >
> > enum ttu_flags {
> > - TTU_UNMAP = 1, /* unmap mode */
> > - TTU_MIGRATION = 2, /* migration mode */
> > - TTU_MUNLOCK = 4, /* munlock mode */
> > -
> > - TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
> > - TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
> > - TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
> > + TTU_VMSCAN = 1, /* unmap for vmscan */
> > + TTU_POISON = 2, /* unmap for poison */
> > + TTU_MIGRATION = 4, /* migration mode */
> > + TTU_MUNLOCK = 8, /* munlock mode */
> > +
> > + TTU_IGNORE_MLOCK = (1 << 9), /* ignore mlock */
> > + TTU_IGNORE_ACCESS = (1 << 10), /* don't age */
> > + TTU_IGNORE_HWPOISON = (1 << 11),/* corrupted page is recoverable */
>
> Unless there is a deeper purpose that I am overlooking, I think it would
> be better to leave the _MLOCK, _ACCESS, and _HWPOISON at their original
> values. I just can't quite see why they would need to start at bit 9
> instead of bit 8...

This code change to have various TTU_* be bitflag instead of value. I am
not sure what was the win in that, would need to dig up that patch that
did that. But in all the case i preserve that change here hence starting
at 9.
>
> > };
> >
> > #ifdef CONFIG_MMU
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index a7a89eb..ba176c4 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -887,7 +887,7 @@ static int page_action(struct page_state *ps, struct page *p,
> > static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
> > int trapno, int flags, struct page **hpagep)
> > {
> > - enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
> > + enum ttu_flags ttu = TTU_POISON | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
> > struct address_space *mapping;
> > LIST_HEAD(tokill);
> > int ret;
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 6d24fd6..5a7d286 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1163,7 +1163,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
> > }
> >
> > ret = shrink_page_list(&clean_pages, zone, &sc,
> > - TTU_UNMAP|TTU_IGNORE_ACCESS,
> > + TTU_VMSCAN|TTU_IGNORE_ACCESS,
> > &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
> > list_splice(&clean_pages, page_list);
> > mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
> > @@ -1518,7 +1518,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
> > if (nr_taken == 0)
> > return 0;
> >
> > - nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
> > + nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_VMSCAN,
> > &nr_dirty, &nr_unqueued_dirty, &nr_congested,
> > &nr_writeback, &nr_immediate,
> > false);
> > --
> > 1.9.0
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@kvack.org. For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> >
>
> Other than that, looks good.
>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
>
> thanks,
> John H.

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