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SubjectRe: BUG: Bad page state [was: Strange oopses in 2.6.30]
Date
Hi

Thank you new version.

> ==== CUT HERE ====
> mm: Warn once when a page is freed with PG_mlocked set
>
> When a page is freed with the PG_mlocked set, it is considered an unexpected
> but recoverable situation. A counter records how often this event happens
> but it is easy to miss that this event has occured at all. This patch warns
> once when PG_mlocked is set to prompt debuggers to check the counter to
> see how often it is happening.
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> ---
> mm/page_alloc.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 5d714f8..519ea6e 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -495,8 +495,16 @@ static inline void free_page_mlock(struct page *page)
> static void free_page_mlock(struct page *page) { }
> #endif
>
> -static inline int free_pages_check(struct page *page)
> -{
> +static inline int free_pages_check(struct page *page, int wasMlocked)
> +{
> + if (unlikely(wasMlocked)) {
> + WARN_ONCE(1, KERN_WARNING
> + "Page flag mlocked set for process %s at pfn:%05lx\n"
> + "page:%p flags:0x%lX\n",

0x%lX is a bit redundunt.
%lX insert "0x" string by itself, I think.


> + current->comm, page_to_pfn(page),
> + page, page->flags|__PG_MLOCKED);
> + }
> +
> if (unlikely(page_mapcount(page) |
> (page->mapping != NULL) |
> (atomic_read(&page->_count) != 0) |
> @@ -562,7 +570,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
> kmemcheck_free_shadow(page, order);
>
> for (i = 0 ; i < (1 << order) ; ++i)
> - bad += free_pages_check(page + i);
> + bad += free_pages_check(page + i, wasMlocked);
> if (bad)
> return;
>
> @@ -1027,7 +1035,7 @@ static void free_hot_cold_page(struct page *page, int cold)
>
> if (PageAnon(page))
> page->mapping = NULL;
> - if (free_pages_check(page))
> + if (free_pages_check(page, wasMlocked))
> return;
>
> if (!PageHighMem(page)) {

Other part looks fine. thanks.





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