The patch titled
Subject: mm/debug_pagealloc.c: don't allocate page_ext if we don't use guard page
has been added to the -mm tree. Its filename is
mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page.patch
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From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: mm/debug_pagealloc.c: don't allocate page_ext if we don't use guard page
What debug_pagealloc does is just mapping/unmapping page table.
Basically, it doesn't need additional memory space to memorize something.
But, with guard page feature, it requires additional memory to distinguish
if the page is for guard or not. Guard page is only used when
debug_guardpage_minorder is non-zero so this patch removes additional
memory allocation (page_ext) if debug_guardpage_minorder is zero.
It saves memory if we just use debug_pagealloc and not guard page.
Link: http://lkml.kernel.org/r/1471315879-32294-3-git-send-email-iamjoonsoo.kim@xxxxxxx
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page mm/page_alloc.c
--- a/mm/page_alloc.c~mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page
+++ a/mm/page_alloc.c
@@ -607,6 +607,9 @@ static bool need_debug_guardpage(void)
if (!debug_pagealloc_enabled())
return false;
+ if (!debug_guardpage_minorder())
+ return false;
+
return true;
}
@@ -615,6 +618,9 @@ static void init_debug_guardpage(void)
if (!debug_pagealloc_enabled())
return;
+ if (!debug_guardpage_minorder())
+ return;
+
_debug_guardpage_enabled = true;
}
@@ -635,7 +641,7 @@ static int __init debug_guardpage_minord
pr_info("Setting debug_guardpage_minorder to %lu\n", res);
return 0;
}
-__setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
+early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
static inline bool set_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype)
_
Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are
mm-debug_pagealloc-clean-up-guard-page-handling-code.patch
mm-debug_pagealloc-dont-allocate-page_ext-if-we-dont-use-guard-page.patch
mm-page_owner-move-page_owner-specific-function-to-page_ownerc.patch
mm-page_ext-rename-offset-to-index.patch
mm-page_ext-support-extra-space-allocation-by-page_ext-user.patch
mm-page_owner-dont-define-fields-on-struct-page_ext-by-hard-coding.patch
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