From 9f1eb38e0e1131e75cc4ac684391b25d70282589 Mon Sep 17 00:00:00 2001 From: Oscar Salvador Date: Fri, 28 Dec 2018 00:37:57 -0800 Subject: [PATCH] mm, kmemleak: little optimization while scanning kmemleak_scan() goes through all online nodes and tries to scan all used pages. We can do better and use pfn_to_online_page(), so in case we have CONFIG_MEMORY_HOTPLUG, offlined pages will be skiped automatically. For boxes where CONFIG_MEMORY_HOTPLUG is not present, pfn_to_online_page() will fallback to pfn_valid(). Another little optimization is to check if the page belongs to the node we are currently checking, so in case we have nodes interleaved we will not check the same pfn multiple times. I ran some tests: Add some memory to node1 and node2 making it interleaved: (qemu) object_add memory-backend-ram,id=ram0,size=1G (qemu) device_add pc-dimm,id=dimm0,memdev=ram0,node=1 (qemu) object_add memory-backend-ram,id=ram1,size=1G (qemu) device_add pc-dimm,id=dimm1,memdev=ram1,node=2 (qemu) object_add memory-backend-ram,id=ram2,size=1G (qemu) device_add pc-dimm,id=dimm2,memdev=ram2,node=1 Then, we offline that memory: # for i in {32..39} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;done # for i in {48..55} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;don # for i in {40..47} ; do echo "offline" > /sys/devices/system/node/node2/memory$i/state;done And we run kmemleak_scan: # echo "scan" > /sys/kernel/debug/kmemleak before the patch: kmemleak: time spend: 41596 us after the patch: kmemleak: time spend: 34899 us [akpm@linux-foundation.org: remove stray newline, per Oscar] Link: http://lkml.kernel.org/r/20181206131918.25099-1-osalvador@suse.de Signed-off-by: Oscar Salvador Reviewed-by: Wei Yang Suggested-by: Michal Hocko Acked-by: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kmemleak.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 877de4fa0720..9c3d2dea0861 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1547,11 +1547,14 @@ static void kmemleak_scan(void) unsigned long pfn; for (pfn = start_pfn; pfn < end_pfn; pfn++) { - struct page *page; + struct page *page = pfn_to_online_page(pfn); - if (!pfn_valid(pfn)) + if (!page) + continue; + + /* only scan pages belonging to this node */ + if (page_to_nid(page) != i) continue; - page = pfn_to_page(pfn); /* only scan if page is in use */ if (page_count(page) == 0) continue;