Reviewed-by: Mark Williamson <[email protected]>
On Tue, Jul 21, 2015 at 9:17 AM, Naoya Horiguchi <[email protected]> wrote: > On Tue, Jul 14, 2015 at 06:37:49PM +0300, Konstantin Khlebnikov wrote: >> This patch sets bit 56 in pagemap if this page is mapped only once. >> It allows to detect exclusively used pages without exposing PFN: >> >> present file exclusive state >> 0 0 0 non-present >> 1 1 0 file page mapped somewhere else >> 1 1 1 file page mapped only here >> 1 0 0 anon non-CoWed page (shared with parent/child) >> 1 0 1 anon CoWed page (or never forked) >> >> CoWed pages in (MAP_FILE | MAP_PRIVATE) areas are anon in this context. >> >> MMap-exclusive bit doesn't reflect potential page-sharing via swapcache: >> page could be mapped once but has several swap-ptes which point to it. >> Application could detect that by swap bit in pagemap entry and touch >> that pte via /proc/pid/mem to get real information. >> >> Signed-off-by: Konstantin Khlebnikov <[email protected]> >> Requested-by: Mark Williamson <[email protected]> >> Link: >> http://lkml.kernel.org/r/caevpba+_ryackhodzrrvqls80iy0sqpdrd0aap_-tgnx3y9...@mail.gmail.com > > Reviewed-by: Naoya Horiguchi <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
