linux-kernel - Re: [PATCH v9] mm: support madvise(MADV

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Message-ID: <20140701145058.GA2084@node.dhcp.inet.fi>
Date:	Tue, 1 Jul 2014 17:50:58 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Jason Evans <je@...com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>
Subject: Re: [PATCH v9] mm: support madvise(MADV_FREE)

On Tue, Jul 01, 2014 at 09:36:15AM +0900, Minchan Kim wrote:
> +	do {
> +		/*
> +		 * XXX: We can optimize with supporting Hugepage free
> +		 * if the range covers.
> +		 */
> +		next = pmd_addr_end(addr, end);
> +		if (pmd_trans_huge(*pmd))
> +			split_huge_page_pmd(vma, addr, pmd);

Could you implement proper THP support before upstreaming the feature?
It shouldn't be a big deal.

> +		/*
> +		 * Here there can be other concurrent MADV_DONTNEED or
> +		 * trans huge page faults running, and if the pmd is
> +		 * none or trans huge it can change under us. This is
> +		 * because MADV_LAZYFREE holds the mmap_sem in read
> +		 * mode.
> +		 */
> +		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
> +			goto next;
> +		next = madvise_free_pte_range(tlb, vma, pmd, addr, next);
> +next:
> +		cond_resched();
> +	} while (pmd++, addr = next, addr != end);

-- 
 Kirill A. Shutemov
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