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Re: [PATCH v5 01/12] mm: support madvise(MADV_FREE)

From Mika Penttilä <mika.penttila@nextfour.com>
Newsgroups linux.kernel
Subject Re: [PATCH v5 01/12] mm: support madvise(MADV_FREE)
Date 2015-11-30 09:30 +0100
Message-ID <qAs0p-17U-5@gated-at.bofh.it> (permalink)
References <qAqrD-8vQ-3@gated-at.bofh.it> <qAqrE-8vQ-15@gated-at.bofh.it>
Organization linux.* mail to news gateway

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> +		 * If pmd isn't transhuge but the page is THP and
> +		 * is owned by only this process, split it and
> +		 * deactivate all pages.
> +		 */
> +		if (PageTransCompound(page)) {
> +			if (page_mapcount(page) != 1)
> +				goto out;
> +			get_page(page);
> +			if (!trylock_page(page)) {
> +				put_page(page);
> +				goto out;
> +			}
> +			pte_unmap_unlock(orig_pte, ptl);
> +			if (split_huge_page(page)) {
> +				unlock_page(page);
> +				put_page(page);
> +				pte_offset_map_lock(mm, pmd, addr, &ptl);
> +				goto out;
> +			}
> +			pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
> +			pte--;
> +			addr -= PAGE_SIZE;
> +			continue;
> +		}

looks like this leaks page count if split_huge_page() is succesfull
(returns zero).

--Mika

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Thread

[PATCH v5 00/12] MADV_FREE support Minchan Kim <minchan@kernel.org> - 2015-11-30 07:50 +0100
  [PATCH v5 01/12] mm: support madvise(MADV_FREE) Minchan Kim <minchan@kernel.org> - 2015-11-30 07:50 +0100
    Re: [PATCH v5 01/12] mm: support madvise(MADV_FREE) Mika Penttilä <mika.penttila@nextfour.com> - 2015-11-30 09:30 +0100
      Re: [PATCH v5 01/12] mm: support madvise(MADV_FREE) Minchan Kim <minchan@kernel.org> - 2015-11-30 10:30 +0100
  [PATCH v5 04/12] mm: free swp_entry in madvise_free Minchan Kim <minchan@kernel.org> - 2015-11-30 07:50 +0100
  [PATCH v5 02/12] mm: define MADV_FREE for some arches Minchan Kim <minchan@kernel.org> - 2015-11-30 07:50 +0100
  [PATCH v5 03/12] arch: uapi: asm: mman.h: Let MADV_FREE have same value for all architectures Minchan Kim <minchan@kernel.org> - 2015-11-30 07:50 +0100

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