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23 October 2021, 00:29:24 UTC
Revision 9e7814404b77c3e8920bee4277162bf3a7460505 authored by KAMEZAWA Hiroyuki on 19 October 2012, 08:00:55 UTC, committed by Linus Torvalds on 19 October 2012, 21:32:10 UTC 
hold task->mempolicy while numa_maps scans.
 
  /proc/<pid>/numa_maps scans vma and show mempolicy under
  mmap_sem. It sometimes accesses task->mempolicy which can
  be freed without mmap_sem and numa_maps can show some
  garbage while scanning.

This patch tries to take reference count of task->mempolicy at reading
numa_maps before calling get_vma_policy(). By this, task->mempolicy
will not be freed until numa_maps reaches its end.

V2->v3
  -  updated comments to be more verbose.
  -  removed task_lock() in numa_maps code.
V1->V2
  -  access task->mempolicy only once and remember it.  Becase kernel/exit.c
     can overwrite it.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3b641bf
History
Tip revision: 9e7814404b77c3e8920bee4277162bf3a7460505 authored by KAMEZAWA Hiroyuki on 19 October 2012, 08:00:55 UTC
hold task->mempolicy while numa_maps scans.
Tip revision: 9e78144
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usr
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.gitignore -rw-r--r-- 1.2 KB
.mailmap -rw-r--r-- 4.4 KB
COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 92.7 KB
Kbuild -rw-r--r-- 2.5 KB
Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 222.4 KB
Makefile -rw-r--r-- 46.6 KB
README -rw-r--r-- 18.2 KB
REPORTING-BUGS -rw-r--r-- 3.3 KB

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