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authorDave Hansen <dave@sr71.net>2014-01-23 15:52:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-23 16:36:50 -0800
commitf0b791a34cb3cffd2bbc3ca4365c9b719fa2c9f3 (patch)
treec4aa42cd8ecd15eca056a944788f5457e3a370ef /mm/page_alloc.c
parent12ab028be0008640de712ca890dc1a9ae224934d (diff)
mm: print more details for bad_page()
bad_page() is cool in that it prints out a bunch of data about the page. But, I can never remember which page flags are good and which are bad, or whether ->index or ->mapping is required to be NULL. This patch allows bad/dump_page() callers to specify a string about why they are dumping the page and adds explanation strings to a number of places. It also adds a 'bad_flags' argument to bad_page(), which it then dumps out separately from the flags which are actually set. This way, the messages will show specifically why the page was bad, *specifically* which flags it is complaining about, if it was a page flag combination which was the problem. [akpm@linux-foundation.org: switch to pr_alert] Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c72
1 files changed, 54 insertions, 18 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 533e2147d14f..1939f4446a36 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -295,7 +295,7 @@ static inline int bad_range(struct zone *zone, struct page *page)
}
#endif
-static void bad_page(struct page *page)
+static void bad_page(struct page *page, char *reason, unsigned long bad_flags)
{
static unsigned long resume;
static unsigned long nr_shown;
@@ -329,7 +329,7 @@ static void bad_page(struct page *page)
printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n",
current->comm, page_to_pfn(page));
- dump_page(page);
+ dump_page_badflags(page, reason, bad_flags);
print_modules();
dump_stack();
@@ -383,7 +383,7 @@ static int destroy_compound_page(struct page *page, unsigned long order)
int bad = 0;
if (unlikely(compound_order(page) != order)) {
- bad_page(page);
+ bad_page(page, "wrong compound order", 0);
bad++;
}
@@ -392,8 +392,11 @@ static int destroy_compound_page(struct page *page, unsigned long order)
for (i = 1; i < nr_pages; i++) {
struct page *p = page + i;
- if (unlikely(!PageTail(p) || (p->first_page != page))) {
- bad_page(page);
+ if (unlikely(!PageTail(p))) {
+ bad_page(page, "PageTail not set", 0);
+ bad++;
+ } else if (unlikely(p->first_page != page)) {
+ bad_page(page, "first_page not consistent", 0);
bad++;
}
__ClearPageTail(p);
@@ -618,12 +621,23 @@ out:
static inline int free_pages_check(struct page *page)
{
- if (unlikely(page_mapcount(page) |
- (page->mapping != NULL) |
- (atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
- (mem_cgroup_bad_page_check(page)))) {
- bad_page(page);
+ char *bad_reason = NULL;
+ unsigned long bad_flags = 0;
+
+ if (unlikely(page_mapcount(page)))
+ bad_reason = "nonzero mapcount";
+ if (unlikely(page->mapping != NULL))
+ bad_reason = "non-NULL mapping";
+ if (unlikely(atomic_read(&page->_count) != 0))
+ bad_reason = "nonzero _count";
+ if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
+ bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
+ bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
+ }
+ if (unlikely(mem_cgroup_bad_page_check(page)))
+ bad_reason = "cgroup check failed";
+ if (unlikely(bad_reason)) {
+ bad_page(page, bad_reason, bad_flags);
return 1;
}
page_cpupid_reset_last(page);
@@ -843,12 +857,23 @@ static inline void expand(struct zone *zone, struct page *page,
*/
static inline int check_new_page(struct page *page)
{
- if (unlikely(page_mapcount(page) |
- (page->mapping != NULL) |
- (atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_PREP) |
- (mem_cgroup_bad_page_check(page)))) {
- bad_page(page);
+ char *bad_reason = NULL;
+ unsigned long bad_flags = 0;
+
+ if (unlikely(page_mapcount(page)))
+ bad_reason = "nonzero mapcount";
+ if (unlikely(page->mapping != NULL))
+ bad_reason = "non-NULL mapping";
+ if (unlikely(atomic_read(&page->_count) != 0))
+ bad_reason = "nonzero _count";
+ if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
+ bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
+ bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
+ }
+ if (unlikely(mem_cgroup_bad_page_check(page)))
+ bad_reason = "cgroup check failed";
+ if (unlikely(bad_reason)) {
+ bad_page(page, bad_reason, bad_flags);
return 1;
}
return 0;
@@ -6494,12 +6519,23 @@ static void dump_page_flags(unsigned long flags)
printk(")\n");
}
-void dump_page(struct page *page)
+void dump_page_badflags(struct page *page, char *reason, unsigned long badflags)
{
printk(KERN_ALERT
"page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
page, atomic_read(&page->_count), page_mapcount(page),
page->mapping, page->index);
dump_page_flags(page->flags);
+ if (reason)
+ pr_alert("page dumped because: %s\n", reason);
+ if (page->flags & badflags) {
+ pr_alert("bad because of flags:\n");
+ dump_page_flags(page->flags & badflags);
+ }
mem_cgroup_print_bad_page(page);
}
+
+void dump_page(struct page *page, char *reason)
+{
+ dump_page_badflags(page, reason, 0);
+}