The patch titled Subject: ksm: enable KSM page migration has been added to the -mm tree. Its filename is ksm-enable-ksm-page-migration.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins <hughd@xxxxxxxxxx> Subject: 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@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Petr Holasek <pholasek@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Izik Eidus <izik.eidus@xxxxxxxxxxxxxxxxxx> Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 3 +-- mm/migrate.c | 21 +++------------------ 2 files changed, 4 insertions(+), 20 deletions(-) diff -puN mm/mempolicy.c~ksm-enable-ksm-page-migration mm/mempolicy.c --- a/mm/mempolicy.c~ksm-enable-ksm-page-migration +++ a/mm/mempolicy.c @@ -496,9 +496,8 @@ static int check_pte_range(struct vm_are /* * vm_normal_page() filters out zero pages, but there might * still be PageReserved pages to skip, perhaps in a VDSO. - * And we cannot move PageKsm pages sensibly or safely yet. */ - if (PageReserved(page) || PageKsm(page)) + if (PageReserved(page)) continue; nid = page_to_nid(page); if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT)) diff -puN mm/migrate.c~ksm-enable-ksm-page-migration mm/migrate.c --- a/mm/migrate.c~ksm-enable-ksm-page-migration +++ a/mm/migrate.c @@ -731,20 +731,6 @@ static int __unmap_and_move(struct page lock_page(page); } - /* - * Only memory hotplug's offline_pages() caller has locked out KSM, - * and can safely migrate a KSM page. The other cases have skipped - * PageKsm along with PageReserved - but it is only now when we have - * the page lock that we can be certain it will not go KSM beneath us - * (KSM will not upgrade a page from PageAnon to PageKsm when it sees - * its pagecount raised, but only here do we take the page lock which - * serializes that). - */ - if (PageKsm(page) && !offlining) { - rc = -EBUSY; - goto unlock; - } - /* charge against new page */ mem_cgroup_prepare_migration(page, newpage, &mem); @@ -771,7 +757,7 @@ static int __unmap_and_move(struct page * File Caches may use write_page() or lock_page() in migration, then, * just care Anon page here. */ - if (PageAnon(page)) { + if (PageAnon(page) && !PageKsm(page)) { /* * Only page_lock_anon_vma_read() understands the subtleties of * getting a hold on an anon_vma from outside one of its mms. @@ -851,7 +837,6 @@ uncharge: mem_cgroup_end_migration(mem, page, newpage, (rc == MIGRATEPAGE_SUCCESS || rc == MIGRATEPAGE_BALLOON_SUCCESS)); -unlock: unlock_page(page); out: return rc; @@ -1155,7 +1140,7 @@ static int do_move_page_to_node_array(st goto set_status; /* Use PageReserved to check for zero page */ - if (PageReserved(page) || PageKsm(page)) + if (PageReserved(page)) goto put_and_set; pp->page = page; @@ -1317,7 +1302,7 @@ static void do_pages_stat_array(struct m err = -ENOENT; /* Use PageReserved to check for zero page */ - if (!page || PageReserved(page) || PageKsm(page)) + if (!page || PageReserved(page)) goto set_status; err = page_to_nid(page); _ Patches currently in -mm which might be from hughd@xxxxxxxxxx are linux-next.patch revert-x86-mm-make-spurious_fault-check-explicitly-check-the-present-bit.patch pageattr-prevent-pse-and-gloabl-leftovers-to-confuse-pmd-pte_present-and-pmd_huge.patch mm-memcg-only-evict-file-pages-when-we-have-plenty.patch mm-vmscan-save-work-scanning-almost-empty-lru-lists.patch mm-vmscan-clarify-how-swappiness-highest-priority-memcg-interact.patch mm-vmscan-improve-comment-on-low-page-cache-handling.patch mm-vmscan-clean-up-get_scan_count.patch mm-vmscan-clean-up-get_scan_count-fix.patch mm-vmscan-compaction-works-against-zones-not-lruvecs.patch mm-vmscan-compaction-works-against-zones-not-lruvecs-fix.patch mm-reduce-rmap-overhead-for-ex-ksm-page-copies-created-on-swap-faults.patch mm-page_allocc-__setup_per_zone_wmarks-make-min_pages-unsigned-long.patch mm-vmscanc-__zone_reclaim-replace-max_t-with-max.patch mmksm-use-new-hashtable-implementation.patch mm-make-madvisemadv_willneed-support-swap-file-prefetch.patch mm-make-madvisemadv_willneed-support-swap-file-prefetch-fix.patch mm-make-madvisemadv_willneed-support-swap-file-prefetch-fix-fix.patch mm-avoid-calling-pgdat_balanced-needlessly.patch mm-numa-fix-minor-typo-in-numa_next_scan.patch mm-numa-take-thp-into-account-when-migrating-pages-for-numa-balancing.patch mm-numa-handle-side-effects-in-count_vm_numa_events-for-config_numa_balancing.patch mm-move-page-flags-layout-to-separate-header.patch mm-fold-page-_last_nid-into-page-flags-where-possible.patch mm-numa-cleanup-flow-of-transhuge-page-migration.patch mm-dont-inline-page_mapping.patch swap-make-each-swap-partition-have-one-address_space.patch swap-make-each-swap-partition-have-one-address_space-fix.patch swap-add-per-partition-lock-for-swapfile.patch memcg-reduce-the-size-of-struct-memcg-244-fold.patch memcg-reduce-the-size-of-struct-memcg-244-fold-fix.patch ksm-allow-trees-per-numa-node.patch ksm-add-sysfs-abi-documentation.patch ksm-trivial-tidyups.patch ksm-reorganize-ksm_check_stable_tree.patch ksm-get_ksm_page-locked.patch ksm-remove-old-stable-nodes-more-thoroughly.patch ksm-make-ksm-page-migration-possible.patch ksm-make-merge_across_nodes-migration-safe.patch ksm-enable-ksm-page-migration.patch mm-remove-offlining-arg-to-migrate_pages.patch ksm-stop-hotremove-lockdep-warning.patch mm-prevent-addition-of-pages-to-swap-if-may_writepage-is-unset.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html