From: Siddhesh Poyarekar <siddhesh.poyarekar@gmail•com>
To: Mark Salter <msalter@redhat•com>
Cc: linux-next <linux-next@vger•kernel.org>,
linux-kernel <linux-kernel@vger•kernel.org>,
Andrew Morton <akpm@linux-foundation•org>,
Paul Gortmaker <paul.gortmaker@windriver•com>,
Oleg Nesterov <oleg@redhat•com>,
Siddhesh Poyarekar <siddhesh.poyarekar@gmail•com>
Subject: [PATCH 2/2] mm/linux-next: Fix rcu locking in vm_is_stack
Date: Wed, 7 Mar 2012 01:46:34 +0530 [thread overview]
Message-ID: <1331064994-6693-2-git-send-email-siddhesh.poyarekar@gmail.com> (raw)
In-Reply-To: <1331064994-6693-1-git-send-email-siddhesh.poyarekar@gmail.com>
Take rcu read lock before we do anything at all with the threadgroup
list. Also use list_first_entry_rcu to safely get the reference to the
first task in the list.
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail•com>
---
mm/memory.c | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 0ca7fe6..1d5830c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3932,18 +3932,20 @@ pid_t vm_is_stack(struct task_struct *task,
return task->pid;
if (in_group) {
- struct task_struct *t = task;
+ struct task_struct *t;
rcu_read_lock();
- while_each_thread(task, t) {
+ t = list_first_entry_rcu(&task->thread_group,
+ struct task_struct, thread_group);
+ do {
if (vm_is_stack_for_task(t, vma)) {
ret = t->pid;
goto done;
}
- }
+ } while_each_thread(task, t);
+done:
+ rcu_read_unlock();
}
-done:
- rcu_read_unlock();
return ret;
}
--
1.7.7.4
next prev parent reply other threads:[~2012-03-06 20:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-06 14:49 nommu build failure in linux-next Mark Salter
2012-03-06 15:19 ` Siddhesh Poyarekar
2012-03-06 20:16 ` [PATCH 1/2] mm: Fix task_nommu build regression " Siddhesh Poyarekar
2012-03-06 20:16 ` Siddhesh Poyarekar [this message]
2012-03-07 15:38 ` [PATCH 2/2] mm/linux-next: Fix rcu locking in vm_is_stack Oleg Nesterov
2012-03-07 16:05 ` Siddhesh Poyarekar
2012-03-07 22:11 ` Siddhesh Poyarekar
2012-03-08 17:40 ` Oleg Nesterov
2012-03-08 18:35 ` Siddhesh Poyarekar
2012-03-06 20:39 ` [PATCH 1/2] mm: Fix task_nommu build regression in linux-next Andrew Morton
2012-03-07 3:31 ` Siddhesh Poyarekar
2012-03-07 16:43 ` Siddhesh Poyarekar
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