(Cced: Andrew)
On Sat, May 10, 2014 at 11:14:34AM +0800, Chen Yucong wrote:
> For handling a free hugepage in memory failure, the race will happen if
> another thread hwpoisoned this hugepage concurrently. So we need to
> check PageHWPoison instead of !PageHWPoison.
>
> If hwpoison_filter(p) returns true or a race happens, then we need to
> unlock_page(hpage).
>
> Signed-off-by: Chen Yucong <slaoub@xxxxxxxxx>
> Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
I tested this patch on latest linux-next, and confirmed that memory error
on a tail page of a free hugepage is properly handled.
Tested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
And I think this patch should go into all recent stable trees, since this
bug exists since 2.6.36 (because of my patch, sorry.)
> ---
> mm/memory-failure.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 35ef28a..dbf8922 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1081,15 +1081,16 @@ int memory_failure(unsigned long pfn, int
> trapno, int flags)
This linebreak breaks patch format. I guess it's done by your email
client or copy and paste. If it's true, git-send-email might be helpful
to avoid such errors.
Thanks,
Naoya
> return 0;
> } else if (PageHuge(hpage)) {
> /*
> - * Check "just unpoisoned", "filter hit", and
> - * "race with other subpage."
> + * Check "filter hit" and "race with other subpage."
> */
> lock_page(hpage);
> - if (!PageHWPoison(hpage)
> - || (hwpoison_filter(p) && TestClearPageHWPoison(p))
> - || (p != hpage && TestSetPageHWPoison(hpage))) {
> - atomic_long_sub(nr_pages, &num_poisoned_pages);
> - return 0;
> + if (PageHWPoison(hpage)) {
> + if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
> + || (p != hpage && TestSetPageHWPoison(hpage))) {
> + atomic_long_sub(nr_pages, &num_poisoned_pages);
> + unlock_page(hpage);
> + return 0;
> + }
> }
> set_page_hwpoison_huge_page(hpage);
> res = dequeue_hwpoisoned_huge_page(hpage);
> --
> 1.7.10.4
>
>
>
>
>
>
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