sched/numa: enhance vma scanning logic

During Numa scanning make sure only relevant vmas of the tasks are
scanned.

Before:
 All the tasks of a process participate in scanning the vma even if they
 do not access vma in it's lifespan.

Now:
 Except cases of first few unconditional scans, if a process do
 not touch vma (exluding false positive cases of PID collisions)
 tasks no longer scan all vma

Logic used:

1) 6 bits of PID used to mark active bit in vma numab status during
   fault to remember PIDs accessing vma.  (Thanks Mel)

2) Subsequently in scan path, vma scanning is skipped if current PID
   had not accessed vma.

3) First two times we do allow unconditional scan to preserve earlier
   behaviour of scanning.

Acknowledgement to Bharata B Rao <[email protected]> for initial patch to
store pid information and Peter Zijlstra <[email protected]> (Usage of
test and set bit)

Link: https://lkml.kernel.org/r/092f03105c7c1d3450f4636b1ea350407f07640e.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Raghavendra K T <[email protected]>
Suggested-by: Mel Gorman <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Disha Talreja <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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