+ ksm-mem-cgroup-charge-swapin-copy.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     ksm: mem cgroup charge swapin copy
has been added to the -mm tree.  Its filename is
     ksm-mem-cgroup-charge-swapin-copy.patch

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------------------------------------------------------
Subject: ksm: mem cgroup charge swapin copy
From: Hugh Dickins <hugh.dickins@tiscali.co.uk>

But ksm swapping does require one small change in mem cgroup handling. 
When do_swap_page()'s call to ksm_might_need_to_copy() does indeed
substitute a duplicate page to accommodate a different anon_vma (or a the
!PageSwapCache check in mem_cgroup_try_charge_swapin().

That was returning success without charging, on the assumption that
pte_same() would fail after, which is not the case here.  Originally I
proposed that success, so that an unshrinkable mem cgroup at its limit
would not fail unnecessarily; but that's a minor point, and there are
plenty of other places where we may fail an overallocation which might
later prove unnecessary.  So just go ahead and do what all the other
exceptions do: proceed to charge current mm.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff -puN mm/memcontrol.c~ksm-mem-cgroup-charge-swapin-copy mm/memcontrol.c
--- a/mm/memcontrol.c~ksm-mem-cgroup-charge-swapin-copy
+++ a/mm/memcontrol.c
@@ -1737,11 +1737,12 @@ int mem_cgroup_try_charge_swapin(struct 
 		goto charge_cur_mm;
 	/*
 	 * A racing thread's fault, or swapoff, may have already updated
-	 * the pte, and even removed page from swap cache: return success
-	 * to go on to do_swap_page()'s pte_same() test, which should fail.
+	 * the pte, and even removed page from swap cache: in those cases
+	 * do_swap_page()'s pte_same() test will fail; but there's also a
+	 * KSM case which does need to charge the page.
 	 */
 	if (!PageSwapCache(page))
-		return 0;
+		goto charge_cur_mm;
 	mem = try_get_mem_cgroup_from_swapcache(page);
 	if (!mem)
 		goto charge_cur_mm;
_

Patches currently in -mm which might be from hugh.dickins@tiscali.co.uk are

mmap-dont-return-enomem-when-mapcount-is-temporarily-exceeded-in-munmap.patch
mmap-dont-return-enomem-when-mapcount-is-temporarily-exceeded-in-munmap-checkpatch-fixes.patch
vmalloc-adjust-gfp-mask-passed-on-nested-vmalloc-invocation.patch
swap_info-private-to-swapfilec.patch
swap_info-change-to-array-of-pointers.patch
swap_info-include-first_swap_extent.patch
swap_info-include-first_swap_extent-fix.patch
swap_info-include-first_swap_extent-fix-fix.patch
swap_info-miscellaneous-minor-cleanups.patch
swap_info-swap_has_cache-cleanups.patch
swap_info-swap_map-of-chars-not-shorts.patch
swap_info-swap-count-continuations.patch
swap_info-note-swap_map_shmem.patch
swap_info-reorder-its-fields.patch
rmap-fix-the-comment-for-try_to_unmap_anon.patch
oom_kill-use-rss-value-instead-of-vm-size-for-badness.patch
mm-define-page_mapping_flags.patch
mm-mlocking-in-try_to_unmap_one.patch
mm-mlocking-in-try_to_unmap_one-fix.patch
mm-mlocking-in-try_to_unmap_one-fix-fix.patch
mm-config_mmu-for-pg_mlocked.patch
mm-pass-address-down-to-rmap-ones.patch
mm-stop-ptlock-enlarging-struct-page.patch
mm-sigbus-instead-of-abusing-oom.patch
ksm-three-remove_rmap_item_from_tree-cleanups.patch
ksm-remove-redundancies-when-merging-page.patch
ksm-cleanup-some-function-arguments.patch
ksm-singly-linked-rmap_list.patch
ksm-separate-stable_node.patch
ksm-stable_node-point-to-page-and-back.patch
ksm-fix-mlockfreed-to-munlocked.patch
ksm-let-shared-pages-be-swappable.patch
ksm-hold-anon_vma-in-rmap_item.patch
ksm-take-keyhole-reference-to-page.patch
ksm-share-anon-page-without-allocating.patch
ksm-mem-cgroup-charge-swapin-copy.patch
ksm-rmap_walk-to-remove_migation_ptes.patch
ksm-memory-hotremove-migration-only.patch
ksm-remove-unswappable-max_kernel_pages.patch
hugetlb-prevent-deadlock-in-__unmap_hugepage_range-when-alloc_huge_page-fails-2.patch
mm-simplify-try_to_unmap_one.patch
mm-simplify-try_to_unmap_one-fix.patch
elf-kill-use_elf_core_dump.patch
prio_tree-debugging-patch.patch