badpage: keep any bad page out of circulation
Until now the bad_page() checkers have special-cased PageReserved, keeping those pages out of circulation thereafter. Now extend the special case to all: we want to keep ANY page with bad state out of circulation - the "free" page may well be in use by something. Leave the bad state of those pages untouched, for examination by debuggers; except for PageBuddy - leaving that set would risk bringing the page back. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -231,9 +231,9 @@ static void bad_page(struct page *page)
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printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
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KERN_EMERG "Backtrace:\n");
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dump_stack();
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set_page_count(page, 0);
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reset_page_mapcount(page);
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page->mapping = NULL;
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/* Leave bad fields for debug, except PageBuddy could make trouble */
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__ClearPageBuddy(page);
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add_taint(TAINT_BAD_PAGE);
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}
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@ -290,25 +290,31 @@ void prep_compound_gigantic_page(struct page *page, unsigned long order)
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}
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#endif
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static void destroy_compound_page(struct page *page, unsigned long order)
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static int destroy_compound_page(struct page *page, unsigned long order)
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{
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int i;
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int nr_pages = 1 << order;
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int bad = 0;
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if (unlikely(compound_order(page) != order))
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if (unlikely(compound_order(page) != order) ||
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unlikely(!PageHead(page))) {
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bad_page(page);
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bad++;
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}
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if (unlikely(!PageHead(page)))
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bad_page(page);
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__ClearPageHead(page);
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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) |
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(p->first_page != page)))
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if (unlikely(!PageTail(p) | (p->first_page != page))) {
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bad_page(page);
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bad++;
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}
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__ClearPageTail(p);
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}
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return bad;
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}
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static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
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@ -428,7 +434,8 @@ static inline void __free_one_page(struct page *page,
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int migratetype = get_pageblock_migratetype(page);
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if (unlikely(PageCompound(page)))
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destroy_compound_page(page, order);
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if (unlikely(destroy_compound_page(page, order)))
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return;
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page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
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@ -465,15 +472,10 @@ static inline int free_pages_check(struct page *page)
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if (unlikely(page_mapcount(page) |
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(page->mapping != NULL) |
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(page_count(page) != 0) |
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(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
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(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
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bad_page(page);
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/*
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* For now, we report if PG_reserved was found set, but do not
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* clear it, and do not free the page. But we shall soon need
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* to do more, for when the ZERO_PAGE count wraps negative.
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*/
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if (PageReserved(page))
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return 1;
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}
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if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
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page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
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return 0;
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@ -521,11 +523,11 @@ static void __free_pages_ok(struct page *page, unsigned int order)
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{
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unsigned long flags;
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int i;
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int reserved = 0;
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int bad = 0;
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for (i = 0 ; i < (1 << order) ; ++i)
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reserved += free_pages_check(page + i);
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if (reserved)
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bad += free_pages_check(page + i);
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if (bad)
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return;
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if (!PageHighMem(page)) {
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@ -610,17 +612,11 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
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if (unlikely(page_mapcount(page) |
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(page->mapping != NULL) |
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(page_count(page) != 0) |
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(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
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(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
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bad_page(page);
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/*
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* For now, we report if PG_reserved was found set, but do not
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* clear it, and do not allocate the page: as a safety net.
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*/
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if (PageReserved(page))
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return 1;
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}
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page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
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set_page_private(page, 0);
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set_page_refcounted(page);
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