On Fri, Jun 20, 2014 at 1:25 AM, Will Deacon [off-list ref] wrote:

Hi Colin,

On Wed, Jun 18, 2014 at 09:10:09PM +0100, Colin Cross wrote:

quoted

include/linux/sched.h implements TASK_SIZE_OF as TASK_SIZE if it
is not set by the architecture headers.  TASK_SIZE uses the
current task to determine the size of the virtual address space.
On a 64-bit kernel this will cause reading /proc/pid/pagemap of a
64-bit process from a 32-bit process to return EOF when it reads
past 0xffffffff.

Implement TASK_SIZE_OF exactly the same as TASK_SIZE with
test_tsk_thread_flag instead of test_thread_flag.

Looks sane to me.

  Acked-by: Will Deacon [off-list ref]

I take it you're being bitten by this in real software, hence the CC stable
tag?

Will

Yes, it causes memory statistics produced by Android's procrank tool
to be completely wrong.  It applies cleanly to at least 3.10.44,
3.12.22, and 3.14.8.