Messages in this thread | | | Date | Thu, 7 May 2009 11:05:16 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 4/7] proc: export more page flags in /proc/kpageflags |
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On Thu, May 07, 2009 at 10:48:55AM +0800, KOSAKI Motohiro wrote: > > 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@intel.com> 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...
Good point. Updated comment to:
/* * pseudo flags for the well known (anonymous) memory mapped pages * * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the * simple test in page_mapped() is not enough. */ if (!PageSlab(page) && page_mapped(page)) u |= 1 << KPF_MMAP;
Thanks, Fengguang
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