The patch titled
Subject: mm, page_alloc: don't duplicate code in free_pcp_prepare
has been added to the -mm tree. Its filename is
mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, page_alloc: don't duplicate code in free_pcp_prepare
The new free_pcp_prepare() function shares a lot of code with
free_pages_prepare(), which makes this a maintenance risk when some future
patch modifies only one of them. We should be able to achieve the same effect
(skipping free_pages_check() from !DEBUG_VM configs) by adding a parameter to
free_pages_prepare() and making it inline, so the checks (and the order != 0
parts) are eliminated from the call from free_pcp_prepare().
!DEBUG_VM: bloat-o-meter reports no difference, as my gcc was already inlining
free_pages_prepare() and the elimination seems to work as expected
DEBUG_VM bloat-o-meter:
add/remove: 0/1 grow/shrink: 2/0 up/down: 1035/-778 (257)
function old new delta
__free_pages_ok 297 1060 +763
free_hot_cold_page 480 752 +272
free_pages_prepare 778 - -778
Here inlining didn't occur before, and added some code, but it's ok for a debug
option.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
1 file changed, 7 insertions(+), 28 deletions(-)
index b823f00c275b..bc4160bfb36b 100644
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 35 +++++++----------------------------
1 file changed, 7 insertions(+), 28 deletions(-)
diff -puN mm/page_alloc.c~mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare
+++ a/mm/page_alloc.c
@@ -996,7 +996,7 @@ static bool free_pages_prepare(struct pa
#ifdef CONFIG_DEBUG_VM
static inline bool free_pcp_prepare(struct page *page)
{
- return free_pages_prepare(page, 0);
+ return free_pages_prepare(page, 0, true);
}
static inline bool bulkfree_pcp_prepare(struct page *page)
@@ -1006,30 +1006,7 @@ static inline bool bulkfree_pcp_prepare(
#else
static bool free_pcp_prepare(struct page *page)
{
- VM_BUG_ON_PAGE(PageTail(page), page);
-
- trace_mm_page_free(page, 0);
- kmemcheck_free_shadow(page, 0);
- kasan_free_pages(page, 0);
-
- if (PageAnonHead(page))
- page->mapping = NULL;
-
- reset_page_owner(page, 0);
-
- if (!PageHighMem(page)) {
- debug_check_no_locks_freed(page_address(page),
- PAGE_SIZE);
- debug_check_no_obj_freed(page_address(page),
- PAGE_SIZE);
- }
- arch_free_page(page, 0);
- kernel_poison_pages(page, 0, 0);
- kernel_map_pages(page, 0, 0);
-
- page_cpupid_reset_last(page);
- page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
- return true;
+ return free_pages_prepare(page, 0, false);
}
static bool bulkfree_pcp_prepare(struct page *page)
@@ -1201,7 +1178,8 @@ void __meminit reserve_bootmem_region(un
}
}
-static bool free_pages_prepare(struct page *page, unsigned int order)
+static __always_inline bool free_pages_prepare(struct page *page, unsigned int order,
+ bool check_free)
{
int bad = 0;
@@ -1233,7 +1211,8 @@ static bool free_pages_prepare(struct pa
}
if (PageAnonHead(page))
page->mapping = NULL;
- bad += free_pages_check(page);
+ if (check_free)
+ bad += free_pages_check(page);
if (bad)
return false;
@@ -1260,7 +1239,7 @@ static void __free_pages_ok(struct page
int migratetype;
unsigned long pfn = page_to_pfn(page);
- if (!free_pages_prepare(page, order))
+ if (!free_pages_prepare(page, order, true))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-page_alloc-only-check-pagecompound-for-high-order-pages.patch
mm-page_alloc-use-new-pageanonhead-helper-in-the-free-page-fast-path.patch
mm-page_alloc-reduce-branches-in-zone_statistics.patch
mm-page_alloc-inline-zone_statistics.patch
mm-page_alloc-inline-the-fast-path-of-the-zonelist-iterator.patch
mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation.patch
mm-page_alloc-avoid-unnecessary-zone-lookups-during-pageblock-operations.patch
mm-page_alloc-convert-alloc_flags-to-unsigned.patch
mm-page_alloc-convert-nr_fair_skipped-to-bool.patch
mm-page_alloc-remove-unnecessary-local-variable-in-get_page_from_freelist.patch
mm-page_alloc-remove-unnecessary-initialisation-in-get_page_from_freelist.patch
mm-page_alloc-remove-unnecessary-initialisation-from-__alloc_pages_nodemask.patch
mm-page_alloc-simplify-last-cpupid-reset.patch
mm-page_alloc-move-__gfp_hardwall-modifications-out-of-the-fastpath.patch
mm-page_alloc-check-once-if-a-zone-has-isolated-pageblocks.patch
mm-page_alloc-check-once-if-a-zone-has-isolated-pageblocks-fix.patch
mm-page_alloc-shorten-the-page-allocator-fast-path.patch
mm-page_alloc-reduce-cost-of-fair-zone-allocation-policy-retry.patch
mm-page_alloc-shortcut-watermark-checks-for-order-0-pages.patch
mm-page_alloc-avoid-looking-up-the-first-zone-in-a-zonelist-twice.patch
mm-page_alloc-remove-field-from-alloc_context.patch
mm-page_alloc-check-multiple-page-fields-with-a-single-branch.patch
mm-page_alloc-un-inline-the-bad-part-of-free_pages_check.patch
mm-page_alloc-pull-out-side-effects-from-free_pages_check.patch
mm-page_alloc-remove-unnecessary-variable-from-free_pcppages_bulk.patch
mm-page_alloc-inline-pageblock-lookup-in-page-free-fast-paths.patch
mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch
mm-page_alloc-defer-debugging-checks-of-pages-allocated-from-the-pcp.patch
mm-page_alloc-dont-duplicate-code-in-free_pcp_prepare.patch
--
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