On Fri, 07 Feb 2014 16:16:04 -0500 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
> # Resending due to sending failure. Sorry if you received twice.
> ---
> mce-test detected a test failure when injecting error to a thp tail page.
> This is because we take page refcount of the tail page in madvise_hwpoison()
> while the fix in commit a3e0f9e47d5e ("mm/memory-failure.c: transfer page
> count from head page to tail page after split thp") assumes that we always
> take refcount on the head page.
>
> When a real memory error happens we take refcount on the head page where
> memory_failure() is called without MF_COUNT_INCREASED set, so it seems to me
> that testing memory error on thp tail page using madvise makes little sense.
>
> This patch cancels moving refcount in !MF_COUNT_INCREASED for valid testing.
>
> ...
>
> --- v3.14-rc1.orig/mm/memory-failure.c
> +++ v3.14-rc1/mm/memory-failure.c
> @@ -1042,8 +1042,10 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
> * to it. Similarly, page lock is shifted.
> */
> if (hpage != p) {
> - put_page(hpage);
> - get_page(p);
> + if (!(flags && MF_COUNT_INCREASED)) {
s/&&/&/
Please carefully retest this, make sure that both cases are covered?
> + put_page(hpage);
> + get_page(p);
> + }
> lock_page(p);
> unlock_page(hpage);
> *hpagep = p;
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