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Commit f0b791a3 authored by Dave Hansen's avatar Dave Hansen Committed by Linus Torvalds
Browse files

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: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 12ab028b

include/linux/mm.h

+3 −1
Original line number Diff line number Diff line
@@ -2029,7 +2029,9 @@ extern void shake_page(struct page *p, int access); 
extern atomic_long_t num_poisoned_pages;

extern int soft_offline_page(struct page *page, int flags);



extern void dump_page(struct page *page);

extern void dump_page(struct page *page, char *reason);

extern void dump_page_badflags(struct page *page, char *reason,

			       unsigned long badflags);



#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)

extern void clear_huge_page(struct page *page,

mm/balloon_compaction.c

+2 −2
Original line number Diff line number Diff line
@@ -267,7 +267,7 @@ void balloon_page_putback(struct page *page) 
		put_page(page);

	} else {

		WARN_ON(1);

		dump_page(page);

		dump_page(page, "not movable balloon page");

	}

	unlock_page(page);

}
@@ -287,7 +287,7 @@ int balloon_page_migrate(struct page *newpage, 
	BUG_ON(!trylock_page(newpage));



	if (WARN_ON(!__is_movable_balloon_page(page))) {

		dump_page(page);

		dump_page(page, "not movable balloon page");

		unlock_page(newpage);

		return rc;

	}

mm/memory.c

+1 −1
Original line number Diff line number Diff line
@@ -671,7 +671,7 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 
		current->comm,

		(long long)pte_val(pte), (long long)pmd_val(*pmd));

	if (page)

		dump_page(page);

		dump_page(page, "bad pte");

	printk(KERN_ALERT

		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",

		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);

mm/memory_hotplug.c

+1 −1
Original line number Diff line number Diff line
@@ -1309,7 +1309,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) 
#ifdef CONFIG_DEBUG_VM

			printk(KERN_ALERT "removing pfn %lx from LRU failed\n",

			       pfn);

			dump_page(page);

			dump_page(page, "failed to remove from LRU");

#endif

			put_page(page);

			/* Because we don't have big zone->lock. we should

mm/page_alloc.c

+54 −18
Original line number Diff line number Diff line
@@ -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 @@ static inline void __free_one_page(struct page *page, 


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);

}