forked from luck/tmp_suning_uos_patched
ksm: enable KSM page migration
Migration of KSM pages is now safe: remove the PageKsm restrictions from mempolicy.c and migrate.c. But keep PageKsm out of __unmap_and_move()'s anon_vma contortions, which are irrelevant to KSM: it looks as if that code was preventing hotremove migration of KSM pages, unless they happened to be in swapcache. There is some question as to whether enforcing a NUMA mempolicy migration ought to migrate KSM pages, mapped into entirely unrelated processes; but moving page_mapcount > 1 is only permitted with MPOL_MF_MOVE_ALL anyway, and it seems reasonable to assume that you wouldn't set MADV_MERGEABLE on any area where this is a worry. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4146d2d673
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@ -496,9 +496,8 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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/*
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* vm_normal_page() filters out zero pages, but there might
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* still be PageReserved pages to skip, perhaps in a VDSO.
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* And we cannot move PageKsm pages sensibly or safely yet.
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*/
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if (PageReserved(page) || PageKsm(page))
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if (PageReserved(page))
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continue;
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nid = page_to_nid(page);
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if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
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21
mm/migrate.c
21
mm/migrate.c
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@ -731,20 +731,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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lock_page(page);
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}
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/*
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* Only memory hotplug's offline_pages() caller has locked out KSM,
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* and can safely migrate a KSM page. The other cases have skipped
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* PageKsm along with PageReserved - but it is only now when we have
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* the page lock that we can be certain it will not go KSM beneath us
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* (KSM will not upgrade a page from PageAnon to PageKsm when it sees
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* its pagecount raised, but only here do we take the page lock which
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* serializes that).
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*/
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if (PageKsm(page) && !offlining) {
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rc = -EBUSY;
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goto unlock;
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}
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/* charge against new page */
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mem_cgroup_prepare_migration(page, newpage, &mem);
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@ -771,7 +757,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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* File Caches may use write_page() or lock_page() in migration, then,
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* just care Anon page here.
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*/
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if (PageAnon(page)) {
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if (PageAnon(page) && !PageKsm(page)) {
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/*
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* Only page_lock_anon_vma_read() understands the subtleties of
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* getting a hold on an anon_vma from outside one of its mms.
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@ -851,7 +837,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
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mem_cgroup_end_migration(mem, page, newpage,
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(rc == MIGRATEPAGE_SUCCESS ||
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rc == MIGRATEPAGE_BALLOON_SUCCESS));
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unlock:
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unlock_page(page);
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out:
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return rc;
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@ -1155,7 +1140,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
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goto set_status;
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/* Use PageReserved to check for zero page */
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if (PageReserved(page) || PageKsm(page))
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if (PageReserved(page))
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goto put_and_set;
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pp->page = page;
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@ -1317,7 +1302,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
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err = -ENOENT;
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/* Use PageReserved to check for zero page */
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if (!page || PageReserved(page) || PageKsm(page))
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if (!page || PageReserved(page))
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goto set_status;
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err = page_to_nid(page);
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