[PATCH V2 0/6] VA to numa node information

[Prakash Sangappa <prakash.sangappa@oracle.com>]

For analysis purpose it is useful to have numa node information
corresponding mapped virtual address ranges of a process. Currently,
the file /proc/<pid>/numa_maps provides list of numa nodes from where pages
are allocated per VMA of a process. This is not useful if an user needs to
determine which numa node the mapped pages are allocated from for a
particular address range. It would have helped if the numa node information
presented in /proc/<pid>/numa_maps was broken down by VA ranges showing the
exact numa node from where the pages have been allocated.

The format of /proc/<pid>/numa_maps file content is dependent on
/proc/<pid>/maps file content as mentioned in the manpage. i.e one line
entry for every VMA corresponding to entries in /proc/<pids>/maps file.
Therefore changing the output of /proc/<pid>/numa_maps may not be possible.

This patch set introduces the file /proc/<pid>/numa_vamaps which
will provide proper break down of VA ranges by numa node id from where the
mapped pages are allocated. For Address ranges not having any pages mapped,
a '-' is printed instead of numa node id.

Includes support to lseek, allowing seeking to a specific process Virtual
address(VA) starting from where the address range to numa node information
can to be read from this file.

The new file /proc/<pid>/numa_vamaps will be governed by ptrace access
mode PTRACE_MODE_READ_REALCREDS.

See following for previous discussion about this proposal

https://marc.info/?t=152524073400001&r=1&w=2


Prakash Sangappa (6):
  Add check to match numa node id when gathering pte stats
  Add /proc/<pid>/numa_vamaps file for numa node information
  Provide process address range to numa node id mapping
  Add support to lseek /proc/<pid>/numa_vamaps file
  File /proc/<pid>/numa_vamaps access needs PTRACE_MODE_READ_REALCREDS
    check
  /proc/pid/numa_vamaps: document in Documentation/filesystems/proc.txt

 Documentation/filesystems/proc.txt |  21 +++
 fs/proc/base.c                     |   6 +-
 fs/proc/internal.h                 |   1 +
 fs/proc/task_mmu.c                 | 265 ++++++++++++++++++++++++++++++++++++-
 4 files changed, 285 insertions(+), 8 deletions(-)

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2.7.4