Hi Naoya, On Thu, Aug 22, 2013 at 03:06:05PM -0400, Naoya Horiguchi wrote: >On Thu, Aug 22, 2013 at 05:48:25PM +0800, Wanpeng Li wrote: >> Set pageblock migration type will hold zone->lock which is heavy contended >> in system to avoid race. However, soft offline page will set pageblock >> migration type twice during get page if the page is in used, not hugetlbfs >> page and not on lru list. There is unnecessary to set the pageblock migration >> type and hold heavy contended zone->lock again if the first round get page >> have already set the pageblock to right migration type. > >Can we use get_pageblock_migratetype() outside zone->lock? > I think the trick here is migration type is MIGRATE_ISOLATE. There are two parts can change MIGRATE_ISOLATE except hwpoison. One is memory hoplug, however, we hold lock_memory_hotplug() which avoid race. The second is CMA which umovable page allocation requst can't fallback to. So I think it's safe here. Regards, Wanpeng Li >There are surely some users which call this function outside >zone->lock like free_hot_cold_pages(), __free_pages, etc., >but I think that there's a race window where migratetype is >updated just after get_pageblock_migratetype() check. > >> Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> >> --- >> mm/memory-failure.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index 6bfd51e..3bfb45f 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -1413,7 +1413,8 @@ static int __get_any_page(struct page *p, unsigned long pfn, int flags) >> * was free. This flag should be kept set until the source page >> * is freed and PG_hwpoison on it is set. >> */ >> - set_migratetype_isolate(p, true); >> + if (get_pageblock_migratetype(p) == MIGRATE_ISOLATE) > >You meant '!=', right? > >Thanks, >Naoya Horiguchi > >> + set_migratetype_isolate(p, true); >> /* >> * When the target page is a free hugepage, just remove it >> * from free hugepage list. >> -- >> 1.8.1.2 >> > >-- >To unsubscribe, send a message with 'unsubscribe linux-mm' in >the body to majordomo@xxxxxxxxx. For more info on Linux MM, >see: http://www.linux-mm.org/ . >Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>