Andrew Morton <a...@linux-foundation.org> writes:
> On Sun, 8 Apr 2018 11:37:37 +0800 "Huang, Ying" <ying.hu...@intel.com> wrote:
>> From: Huang Ying <ying.hu...@intel.com>
>> The swap offset reported by /proc/<pid>/pagemap may be not correct for
>> PMD migration entry. If addr passed into pagemap_range() isn't
> pagemap_pmd_range(), yes?
Yes. Sorry for typo.
>> aligned with PMD start address,
> How can this situation come about?
After open /proc/<pid>/pagemap, if user seeks to a page whose address
doesn't aligned with PMD start address. I have verified this with a
simple test program.
>> the swap offset reported doesn't
>> reflect this. And in the loop to report information of each sub-page,
>> the swap offset isn't increased accordingly as that for PFN.
>> BTW: migration swap entries have PFN information, do we need to
>> restrict whether to show them?
> For what reason? Address obfuscation?
This is an existing feature for PFN report of /proc/<pid>/pagemap,
reason is in following commit log. I am wondering whether that is
necessary for migration swap entries too.
Author: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
AuthorDate: Mon Mar 9 23:11:12 2015 +0200
Commit: Linus Torvalds <torva...@linux-foundation.org>
CommitDate: Tue Mar 17 09:31:30 2015 -0700
pagemap: do not leak physical addresses to non-privileged userspace
As pointed by recent post on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do
This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
[ Eventually we might want to do anything more finegrained, but for now
this is the simple model. - Linus ]
Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
Acked-by: Konstantin Khlebnikov <khlebni...@openvz.org>
Acked-by: Andy Lutomirski <l...@amacapital.net>
Cc: Pavel Emelyanov <xe...@parallels.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Mark Seaborn <mseab...@chromium.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>