Re: [PATCH 4/7] proc: export more page flags in /proc/kpageflags

From: KOSAKI Motohiro
Date: Wed May 06 2009 - 22:49:18 EST


> On Thu, May 07, 2009 at 10:40:16AM +0800, Minchan Kim wrote:
> > On Thu, 07 May 2009 09:21:21 +0800
> > Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
> >
> > > + * pseudo flags for the well known (anonymous) memory mapped pages
> > > + */
> > > + if (!PageSlab(page) && page_mapped(page))
> > > + u |= 1 << KPF_MMAP;
> > > + if (PageAnon(page))
> > > + u |= 1 << KPF_ANON;
> >
> > Why do you check PageSlab on user pages ?
> > Is there any case that PageSlab == true && page_mapped == true ?
>
> Yes at least for SLUB: it reuses page->_mapcount, so page_mapped() is
> meaningless for slab pages.

this question and answer implies more comment required...



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