On Tue, Jul 14, 2015 at 9:52 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 14 Jul 2015 18:37:34 +0300 Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> wrote: > >> This patchset makes pagemap useable again in the safe way (after row hammer >> bug it was made CAP_SYS_ADMIN-only). This patchset restores access for >> non-privileged users but hides PFNs from them. > > Documentation/vm/pagemap.txt hasn't been updated to describe these > privilege issues? Will do. Too much time passed between versions, I planned but forgot about that. > >> Also it adds bit 'map-exlusive' which is set if page is mapped only here: >> it helps in estimation of working set without exposing pfns and allows to >> distinguish CoWed and non-CoWed private anonymous pages. >> >> Second patch removes page-shift bits and completes migration to the new >> pagemap format: flags soft-dirty and mmap-exlusive are available only >> in the new format. > > I'm not really seeing a description of the new format in these > changelogs. Precisely what got removed, what got added and which > capabilities change the output in what manner? Now pfn (bits 0-54) is zero if task who opened pagemap has no CAP_SYS_ADMIN (system-wide). in v2 format page-shift (bits 55-60) now used for flags: 55 - soft-dirty (added for checkpoint-restore, I guess) 56 - mmap-exclusive (added in last patch) 57-60 - free for use I'll document the history of these changes. > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>