The patch titled
Subject: mm: don't call __page_cache_release for hugetlb
has been added to the -mm tree. Its filename is
mm-dont-call-__page_cache_release-for-hugetlb.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dont-call-__page_cache_release-for-hugetlb.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dont-call-__page_cache_release-for-hugetlb.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm: don't call __page_cache_release for hugetlb
__put_compound_page() calls __page_cache_release() to do some freeing
work, but it's obviously for thps, not for hugetlb. We don't care because
PageLRU is always cleared and page->mem_cgroup is always NULL for hugetlb.
But it's not correct and has potential risks, so let's make it
conditional.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swap.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff -puN mm/swap.c~mm-dont-call-__page_cache_release-for-hugetlb mm/swap.c
--- a/mm/swap.c~mm-dont-call-__page_cache_release-for-hugetlb
+++ a/mm/swap.c
@@ -31,6 +31,7 @@
#include <linux/memcontrol.h>
#include <linux/gfp.h>
#include <linux/uio.h>
+#include <linux/hugetlb.h>
#include "internal.h"
@@ -75,7 +76,14 @@ static void __put_compound_page(struct p
{
compound_page_dtor *dtor;
- __page_cache_release(page);
+ /*
+ * __page_cache_release() is supposed to be called for thp, not for
+ * hugetlb. This is because hugetlb page does never have PageLRU set
+ * (it's never listed to any LRU lists) and no memcg routines should
+ * be called for hugetlb (it has a separate hugetlb_cgroup.)
+ */
+ if (!PageHuge(page))
+ __page_cache_release(page);
dtor = get_compound_page_dtor(page);
(*dtor)(page);
}
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
mm-refactor-do_wp_page-extract-the-reuse-case.patch
mm-refactor-do_wp_page-rewrite-the-unlock-flow.patch
mm-refactor-do_wp_page-extract-the-page-copy-flow.patch
mm-refactor-do_wp_page-handling-of-shared-vma-into-a-function.patch
mm-mempolicy-migrate_to_node-should-only-migrate-to-node.patch
mm-hugetlb-abort-__get_user_pages-if-current-has-been-oom-killed.patch
mm-memory-failurec-define-page-types-for-action_result-in-one-place.patch
mm-memory-failurec-define-page-types-for-action_result-in-one-place-v3.patch
mm-consolidate-all-page-flags-helpers-in-linux-page-flagsh.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
mm-dont-call-__page_cache_release-for-hugetlb.patch
mm-hugetlb-introduce-pagehugeactive-flag.patch
mm-hugetlb-introduce-pagehugeactive-flag-fix.patch
mm-hugetlb-cleanup-using-pagehugeactive-flag.patch
mm-hugetlb-cleanup-using-pagehugeactive-flag-fix.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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