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) _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
