mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE

Most of the VM_BUG_ON assertions are performed on a page.  Usually, when
one of these assertions fails we'll get a BUG_ON with a call stack and
the registers.

I've recently noticed based on the requests to add a small piece of code
that dumps the page to various VM_BUG_ON sites that the page dump is
quite useful to people debugging issues in mm.

This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
VM_BUG_ON() does, also dumps the page before executing the actual
BUG_ON.

[akpm@linux-foundation.org: fix up includes]
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 10 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1939f4446a3..f18f016cca8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -509,12 +509,12 @@ static inline int page_is_buddy(struct page *page, struct page *buddy,
 		return 0;
 
 	if (page_is_guard(buddy) && page_order(buddy) == order) {
-		VM_BUG_ON(page_count(buddy) != 0);
+		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
 		return 1;
 	}
 
 	if (PageBuddy(buddy) && page_order(buddy) == order) {
-		VM_BUG_ON(page_count(buddy) != 0);
+		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
 		return 1;
 	}
 	return 0;
@@ -564,8 +564,8 @@ static inline void __free_one_page(struct page *page,
 
 	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
 
-	VM_BUG_ON(page_idx & ((1 << order) - 1));
-	VM_BUG_ON(bad_range(zone, page));
+	VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
+	VM_BUG_ON_PAGE(bad_range(zone, page), page);
 
 	while (order < MAX_ORDER-1) {
 		buddy_idx = __find_buddy_index(page_idx, order);
@@ -827,7 +827,7 @@ static inline void expand(struct zone *zone, struct page *page,
 		area--;
 		high--;
 		size >>= 1;
-		VM_BUG_ON(bad_range(zone, &page[size]));
+		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 		if (high < debug_guardpage_minorder()) {
@@ -980,7 +980,7 @@ int move_freepages(struct zone *zone,
 
 	for (page = start_page; page <= end_page;) {
 		/* Make sure we are not inadvertently changing nodes */
-		VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));
+		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
 
 		if (!pfn_valid_within(page_to_pfn(page))) {
 			page++;
@@ -1429,8 +1429,8 @@ void split_page(struct page *page, unsigned int order)
 {
 	int i;
 
-	VM_BUG_ON(PageCompound(page));
-	VM_BUG_ON(!page_count(page));
+	VM_BUG_ON_PAGE(PageCompound(page), page);
+	VM_BUG_ON_PAGE(!page_count(page), page);
 
 #ifdef CONFIG_KMEMCHECK
 	/*
@@ -1577,7 +1577,7 @@ again:
 	zone_statistics(preferred_zone, zone, gfp_flags);
 	local_irq_restore(flags);
 
-	VM_BUG_ON(bad_range(zone, page));
+	VM_BUG_ON_PAGE(bad_range(zone, page), page);
 	if (prep_new_page(page, order, gfp_flags))
 		goto again;
 	return page;
@@ -6021,7 +6021,7 @@ void set_pageblock_flags_group(struct page *page, unsigned long flags,
 	pfn = page_to_pfn(page);
 	bitmap = get_pageblock_bitmap(zone, pfn);
 	bitidx = pfn_to_bitidx(zone, pfn);
-	VM_BUG_ON(!zone_spans_pfn(zone, pfn));
+	VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
 
 	for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
 		if (flags & value)
@@ -6539,3 +6539,4 @@ void dump_page(struct page *page, char *reason)
 {
 	dump_page_badflags(page, reason, 0);
 }
+EXPORT_SYMBOL_GPL(dump_page);