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Date: Thu, 16 Feb 2017 12:52:53 -0500 From: Johannes Weiner <hannes@...xchg.org> To: Shaohua Li <shli@...com> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, Kernel-team@...com, mhocko@...e.com, minchan@...nel.org, hughd@...gle.com, riel@...hat.com, mgorman@...hsingularity.net, akpm@...ux-foundation.org Subject: Re: [PATCH V3 2/7] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list On Tue, Feb 14, 2017 at 11:36:08AM -0800, Shaohua Li wrote: > @@ -126,4 +126,24 @@ static __always_inline enum lru_list page_lru(struct page *page) > > #define lru_to_page(head) (list_entry((head)->prev, struct page, lru)) > > +/* > + * lazyfree pages are clean anonymous pages. They have SwapBacked flag cleared > + * to destinguish normal anonymous pages. > + */ > +static inline void set_page_lazyfree(struct page *page) > +{ > + VM_BUG_ON_PAGE(!PageAnon(page) || !PageSwapBacked(page), page); > + ClearPageSwapBacked(page); > +} > + > +static inline void clear_page_lazyfree(struct page *page) > +{ > + VM_BUG_ON_PAGE(!PageAnon(page) || PageSwapBacked(page), page); > + SetPageSwapBacked(page); > +} > + > +static inline bool page_is_lazyfree(struct page *page) > +{ > + return PageAnon(page) && !PageSwapBacked(page); > +} Sorry for not getting to v2 in time, but I have to say I strongly agree with your first iterations and would much prefer this to be open-coded. IMO this needlessly introduces a new state opaquely called "lazyfree", when really that's just anonymous pages that don't need to be swapped before reclaim - PageAnon && !PageSwapBacked. Very simple MM concept. That especially shows when we later combine it with page_is_file_cache checks like the next patch does. The rest of the patch looks good to me.
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