Messages in this thread | | | Date | Tue, 15 Jul 2014 21:14:40 +0200 | From | Michal Hocko <> | Subject | Re: Where in the code mmap + MAP_ANONYMOUS clears returned pages? |
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On Tue 15-07-14 21:55:03, Alexei Fedotov wrote: > Guys, > > I look into mmap.c code [1] and try to understand where anonymous > memory mapping (mmap + MAP_ANONYMOUS) sets memory to zero. My best > guess is I should dig that somewhere in mmap_region. > > Could you please help me locating the code which makes returned memory > pages clean? Thank you in advance.
mmap doesn't allocate pages which back the mapping directly unless it is told to by MAP_POPULATE. So the clean pages are either allocated during the page fault path when the memory is accessed (see do_anonymous_page for private 4k pages fault, do_huge_pmd_anonymous_page for THP page and MAP_SHARED is left as an excercise for the reader ;)) or in mmap path directly when MAP_POPULATE is specified (see vm_mmap_pgoff which calls mm_populate)
> > [1] http://code.ohloh.net/file?fid=RPa2fuiQ5j_IwR1nymptYBBC3X4&cid=w6qrXNDsMqk > > -- > With best regards / с наилучшими пожеланиями, > Alexei Fedotov / Алексей Федотов, > http://dataved.ru/ > +7 916 562 8095 > > [1] Start using Apache Openmeetings today, http://openmeetings.apache.org/ > [2] Join Alexei Fedotov @linkedin, http://ru.linkedin.com/in/dataved/ > [3] Join Alexei Fedotov @facebook, http://www.facebook.com/openmeetings > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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