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>
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12ab028be0
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f0b791a34c
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@ -2029,7 +2029,9 @@ extern void shake_page(struct page *p, int access);
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extern atomic_long_t num_poisoned_pages;
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extern int soft_offline_page(struct page *page, int flags);
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extern void dump_page(struct page *page);
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extern void dump_page(struct page *page, char *reason);
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extern void dump_page_badflags(struct page *page, char *reason,
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unsigned long badflags);
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#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
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extern void clear_huge_page(struct page *page,
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@ -267,7 +267,7 @@ void balloon_page_putback(struct page *page)
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put_page(page);
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} else {
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WARN_ON(1);
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dump_page(page);
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dump_page(page, "not movable balloon page");
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}
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unlock_page(page);
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}
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@ -287,7 +287,7 @@ int balloon_page_migrate(struct page *newpage,
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BUG_ON(!trylock_page(newpage));
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if (WARN_ON(!__is_movable_balloon_page(page))) {
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dump_page(page);
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dump_page(page, "not movable balloon page");
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unlock_page(newpage);
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return rc;
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}
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@ -671,7 +671,7 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
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current->comm,
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(long long)pte_val(pte), (long long)pmd_val(*pmd));
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if (page)
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dump_page(page);
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dump_page(page, "bad pte");
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printk(KERN_ALERT
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"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
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(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
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@ -1309,7 +1309,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
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#ifdef CONFIG_DEBUG_VM
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printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
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pfn);
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dump_page(page);
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dump_page(page, "failed to remove from LRU");
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#endif
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put_page(page);
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/* Because we don't have big zone->lock. we should
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@ -295,7 +295,7 @@ static inline int bad_range(struct zone *zone, struct page *page)
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}
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#endif
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static void bad_page(struct page *page)
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static void bad_page(struct page *page, char *reason, unsigned long bad_flags)
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{
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static unsigned long resume;
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static unsigned long nr_shown;
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@ -329,7 +329,7 @@ static void bad_page(struct page *page)
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printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n",
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current->comm, page_to_pfn(page));
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dump_page(page);
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dump_page_badflags(page, reason, bad_flags);
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print_modules();
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dump_stack();
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@ -383,7 +383,7 @@ static int destroy_compound_page(struct page *page, unsigned long order)
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int bad = 0;
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if (unlikely(compound_order(page) != order)) {
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bad_page(page);
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bad_page(page, "wrong compound order", 0);
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bad++;
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}
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@ -392,8 +392,11 @@ static int destroy_compound_page(struct page *page, unsigned long order)
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for (i = 1; i < nr_pages; i++) {
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struct page *p = page + i;
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if (unlikely(!PageTail(p) || (p->first_page != page))) {
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bad_page(page);
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if (unlikely(!PageTail(p))) {
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bad_page(page, "PageTail not set", 0);
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bad++;
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} else if (unlikely(p->first_page != page)) {
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bad_page(page, "first_page not consistent", 0);
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bad++;
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}
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__ClearPageTail(p);
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@ -618,12 +621,23 @@ out:
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static inline int free_pages_check(struct page *page)
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{
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if (unlikely(page_mapcount(page) |
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(page->mapping != NULL) |
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(atomic_read(&page->_count) != 0) |
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(page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
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(mem_cgroup_bad_page_check(page)))) {
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bad_page(page);
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char *bad_reason = NULL;
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unsigned long bad_flags = 0;
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if (unlikely(page_mapcount(page)))
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bad_reason = "nonzero mapcount";
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if (unlikely(page->mapping != NULL))
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bad_reason = "non-NULL mapping";
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if (unlikely(atomic_read(&page->_count) != 0))
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bad_reason = "nonzero _count";
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if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
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bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
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bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
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}
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if (unlikely(mem_cgroup_bad_page_check(page)))
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bad_reason = "cgroup check failed";
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if (unlikely(bad_reason)) {
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bad_page(page, bad_reason, bad_flags);
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return 1;
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}
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page_cpupid_reset_last(page);
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@ -843,12 +857,23 @@ static inline void expand(struct zone *zone, struct page *page,
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*/
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static inline int check_new_page(struct page *page)
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{
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if (unlikely(page_mapcount(page) |
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(page->mapping != NULL) |
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(atomic_read(&page->_count) != 0) |
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(page->flags & PAGE_FLAGS_CHECK_AT_PREP) |
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(mem_cgroup_bad_page_check(page)))) {
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bad_page(page);
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char *bad_reason = NULL;
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unsigned long bad_flags = 0;
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if (unlikely(page_mapcount(page)))
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bad_reason = "nonzero mapcount";
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if (unlikely(page->mapping != NULL))
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bad_reason = "non-NULL mapping";
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if (unlikely(atomic_read(&page->_count) != 0))
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bad_reason = "nonzero _count";
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if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
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bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
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bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
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}
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if (unlikely(mem_cgroup_bad_page_check(page)))
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bad_reason = "cgroup check failed";
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if (unlikely(bad_reason)) {
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bad_page(page, bad_reason, bad_flags);
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return 1;
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}
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return 0;
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@ -6494,12 +6519,23 @@ static void dump_page_flags(unsigned long flags)
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printk(")\n");
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}
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void dump_page(struct page *page)
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void dump_page_badflags(struct page *page, char *reason, unsigned long badflags)
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{
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printk(KERN_ALERT
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"page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
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page, atomic_read(&page->_count), page_mapcount(page),
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page->mapping, page->index);
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dump_page_flags(page->flags);
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if (reason)
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pr_alert("page dumped because: %s\n", reason);
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if (page->flags & badflags) {
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pr_alert("bad because of flags:\n");
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dump_page_flags(page->flags & badflags);
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}
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mem_cgroup_print_bad_page(page);
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}
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void dump_page(struct page *page, char *reason)
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{
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dump_page_badflags(page, reason, 0);
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}
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