linux-kernel - Re: [PATCH v1] mm: soft-offline: exit with failure for non anonymous thp

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Message-Id: <20160108123300.843d370916d3248be297d831@linux-foundation.org>
Date:	Fri, 8 Jan 2016 12:33:00 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Naoya Horiguchi <nao.horiguchi@...il.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v1] mm: soft-offline: exit with failure for non
 anonymous thp

On Fri,  8 Jan 2016 16:24:02 +0900 Naoya Horiguchi <n-horiguchi@...jp.nec.com> wrote:

> Currently memory_failure() doesn't handle non anonymous thp case, because we
> can hardly expect the error handling to be successful, and it can just hit
> some corner case which results in BUG_ON or something severe like that.
> This is also a case for soft offline code, so let's make it in the same way.
> 
> ...
>
> --- v4.4-rc8/mm/memory-failure.c
> +++ v4.4-rc8_patched/mm/memory-failure.c
> @@ -1751,9 +1751,11 @@ int soft_offline_page(struct page *page, int flags)
>  		return -EBUSY;
>  	}
>  	if (!PageHuge(page) && PageTransHuge(hpage)) {
> -		if (PageAnon(hpage) && unlikely(split_huge_page(hpage))) {
> -			pr_info("soft offline: %#lx: failed to split THP\n",
> -				pfn);
> +		if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
> +			if (!PageAnon(hpage))
> +				pr_info("soft offline: %#lx: non anonymous thp\n", pfn);
> +			else
> +				pr_info("soft offline: %#lx: thp split failed\n", pfn);
>  			if (flags & MF_COUNT_INCREASED)
>  				put_hwpoison_page(page);
>  			return -EBUSY;

Kirill's
http://ozlabs.org/~akpm/mmots/broken-out/thp-mm-split_huge_page-caller-need-to-lock-page.patch
mucks with this code as well.  Could you please redo this patch against
linux-next?

Thanks.