From 8ef5849fa8a2c7894885e27ee8c8fe06e21a88fd Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 14 Jan 2016 15:18:45 -0800 Subject: [PATCH] mm/cma: always check which page caused allocation failure Now, we have tracepoint in test_pages_isolated() to notify pfn which cannot be isolated. But, in alloc_contig_range(), some error path doesn't call test_pages_isolated() so it's still hard to know exact pfn that causes allocation failure. This patch change this situation by calling test_pages_isolated() in almost error path. In allocation failure case, some overhead is added by this change, but, allocation failure is really rare event so it would not matter. In fatal signal pending case, we don't call test_pages_isolated() because this failure is intentional one. There was a bogus outer_start problem due to unchecked buddy order and this patch also fix it. Before this patch, it didn't matter, because end result is same thing. But, after this patch, tracepoint will report failed pfn so it should be accurate. Signed-off-by: Joonsoo Kim Acked-by: Vlastimil Babka Acked-by: Michal Nazarewicz Cc: David Rientjes Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ca58bfcdadac..2f6d30db4c94 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6725,8 +6725,12 @@ int alloc_contig_range(unsigned long start, unsigned long end, if (ret) return ret; + /* + * In case of -EBUSY, we'd like to know which page causes problem. + * So, just fall through. We will check it in test_pages_isolated(). + */ ret = __alloc_contig_migrate_range(&cc, start, end); - if (ret) + if (ret && ret != -EBUSY) goto done; /* @@ -6753,12 +6757,25 @@ int alloc_contig_range(unsigned long start, unsigned long end, outer_start = start; while (!PageBuddy(pfn_to_page(outer_start))) { if (++order >= MAX_ORDER) { - ret = -EBUSY; - goto done; + outer_start = start; + break; } outer_start &= ~0UL << order; } + if (outer_start != start) { + order = page_order(pfn_to_page(outer_start)); + + /* + * outer_start page could be small order buddy page and + * it doesn't include start page. Adjust outer_start + * in this case to report failed page properly + * on tracepoint in test_pages_isolated() + */ + if (outer_start + (1UL << order) <= start) + outer_start = start; + } + /* Make sure the range is really isolated. */ if (test_pages_isolated(outer_start, end, false)) { pr_info("%s: [%lx, %lx) PFNs busy\n",