Re: [PATCH] __isolate_lru_page: skip unneeded mode check

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> >> @@ -862,15 +862,10 @@ int __isolate_lru_page(struct page *page, int mode,
> >> int file)
> >>        if (!PageLRU(page))
> >>                return ret;
> >>
> >> -       /*
> >> -        * When checking the active state, we need to be sure we are
> >> -        * dealing with comparible boolean values.  Take the logical not
> >> -        * of each.
> >> -        */
> >> -       if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
> >> +       if (mode != ISOLATE_BOTH && (PageActive(page) != mode))
> >>                return ret;
> >
> > no. please read the comment.
> >
> 
> Hm,. I have read it, but still miss it :-).
> PageActive(page) will return an int 0 or 1, mode is also int 0 or 1(
> already != ISOLATE_BOTH).
> There are comparible and why must to be sure to boolean values?

hm, ok. you are right.
please resend this part as individual patch.


> >> -       if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file)
> >> +       if (page_is_file_cache(page) != file)
> >>                return ret;
> >
> > no. please consider lumpy reclaim.
> 
> During lumpy reclaim mode is ISOLATE_BOTH, that case we don't check
> page_is_file_cache() ?  Would you please explain it a little more ,i
> am still unclear about it.
> Thanks a lot.

ISOLATE_BOTH is for to help allocate high order memory. then,
it ignore both PageActive() and page_is_file_cache(). otherwise,
we fail to allocate high order memory.


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