Commits
Greg Thelen committed a879bf582df
mm: grab rcu read lock in move_pages()
The move_pages() usage of find_task_by_vpid() requires rcu_read_lock() to
prevent free_pid() from reclaiming the pid.
Without this patch, RCU warnings are printed in v2.6.38-rc4 move_pages()
with:
CONFIG_LOCKUP_DETECTOR=y
CONFIG_PREEMPT=y
CONFIG_LOCKDEP=y
CONFIG_PROVE_LOCKING=y
CONFIG_PROVE_RCU=y
Previously, migrate_pages() went through a similar transformation
replacing usage of tasklist_lock with rcu read lock:
commit 55cfaa3cbdd29c4919ecb5fb8965c310f357e48c
Author: Zeng Zhaoming <zengzm.kernel@gmail.com>
Date: Thu Dec 2 14:31:13 2010 -0800
mm/mempolicy.c: add rcu read lock to protect pid structure
commit 1e50df39f6e2c3a4a3394df62baa8a213df16c54
Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Thu Jan 13 15:46:14 2011 -0800
mempolicy: remove tasklist_lock from migrate_pages
Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Zeng Zhaoming <zengzm.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>