Messages in this thread Patch in this message | | | From | KOSAKI Motohiro <> | Subject | Re: [merged] mm-mempolicyc-add-rcu-read-lock-to-protect-pid-structure.patch removed from -mm tree | Date | Wed, 8 Dec 2010 16:02:26 +0900 (JST) |
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> > The patch titled > mm/mempolicy.c: add rcu read lock to protect pid structure > has been removed from the -mm tree. Its filename was > mm-mempolicyc-add-rcu-read-lock-to-protect-pid-structure.patch > > This patch was dropped because it was merged into mainline or a subsystem tree > > The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ > > ------------------------------------------------------ > Subject: mm/mempolicy.c: add rcu read lock to protect pid structure > From: Zeng Zhaoming <zengzm.kernel@gmail.com> > > find_task_by_vpid() should be protected by rcu_read_lock(), to prevent > free_pid() reclaiming pid. > > Signed-off-by: Zeng Zhaoming <zengzm.kernel@gmail.com> > Cc: "Paul E. McKenney" <paulmck@us.ibm.com> > Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Cc: Christoph Lameter <cl@linux-foundation.org> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrew, please consider pick following patch too.
=========================================================================== From 9de9f70f74e55d92b5e9057e22fc629405f63295 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Date: Thu, 16 Dec 2010 17:49:23 +0900 Subject: [PATCH] mempolicy: remove tasklist_lock from migrate_pages
Today, tasklist_lock in migrate_pages doesn't protect anything. rcu_read_lock() provide enough protection from pid hash walk.
Reported-by: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> --- mm/mempolicy.c | 3 --- 1 files changed, 0 insertions(+), 3 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 11ff260..9064945 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1308,16 +1308,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, /* Find the mm_struct */ rcu_read_lock(); - read_lock(&tasklist_lock); task = pid ? find_task_by_vpid(pid) : current; if (!task) { - read_unlock(&tasklist_lock); rcu_read_unlock(); err = -ESRCH; goto out; } mm = get_task_mm(task); - read_unlock(&tasklist_lock); rcu_read_unlock(); err = -EINVAL; -- 1.6.5.2
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