From: Joonsoo Kim Date: Sat, 10 Sep 2016 10:34:07 +0000 (+1000) Subject: mm/debug_pagealloc.c: don't allocate page_ext if we don't use guard page X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=756ed4877c012eddb78cbf113743b45b6bdd42eb;p=deliverable%2Flinux.git 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@lge.com Signed-off-by: Joonsoo Kim Reviewed-by: Sergey Senozhatsky Acked-by: Vlastimil Babka Cc: Minchan Kim Cc: Michal Hocko Signed-off-by: Andrew Morton --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 24856609150f..11aabaa45ba5 100644 --- a/mm/page_alloc.c +++ b/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_minorder_setup(char *buf) 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)