From: Anton Vorontsov <anton.vorontsov@linaro.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Paul Mundt <lethal@linux-sh.org>,
Russell King <linux@arm.linux.org.uk>,
Mike Frysinger <vapier@gentoo.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Richard Weinberger <richard@nod.at>,
linux-kernel@vger.kernel.org
Subject: [PATCH 3/8] arm: Fix possible race on task->mm
Date: Tue, 7 Feb 2012 10:50:04 +0400 [thread overview]
Message-ID: <20120207065004.GC1496@oksana.dev.rtsoft.ru> (raw)
In-Reply-To: <20120207064809.GA29061@oksana.dev.rtsoft.ru>
Checking for task->mm is dangerous as ->mm might disappear (exit_mm()
assigns NULL under task_lock(), so tasklist lock is not enough).
We can't use get_task_mm()/mmput() pair as mmput() might sleep,
so let's take the task lock while we care about its mm.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/kernel/smp.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 57db122..85db3f2 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -168,8 +168,10 @@ int __cpu_disable(void)
read_lock(&tasklist_lock);
for_each_process(p) {
+ task_lock(p);
if (p->mm)
cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
+ task_unlock(p);
}
read_unlock(&tasklist_lock);
--
1.7.7.6
next prev parent reply other threads:[~2012-02-07 6:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-07 6:48 [PATCH 0/8] Fixes for common mistakes w/ for_each_process and task->mm Anton Vorontsov
2012-02-07 6:49 ` [PATCH 1/8] sysrq: Fix possible race with exiting task Anton Vorontsov
2012-02-09 1:47 ` David Rientjes
2012-02-07 6:49 ` [PATCH 2/8] sysrq: Properly check for kernel threads Anton Vorontsov
2012-02-09 1:46 ` David Rientjes
2012-02-07 6:50 ` Anton Vorontsov [this message]
2012-02-08 16:08 ` [PATCH 3/8] arm: Fix possible race on task->mm Oleg Nesterov
2012-02-09 15:33 ` Anton Vorontsov
2012-02-09 15:43 ` Anton Vorontsov
2012-02-10 20:21 ` Oleg Nesterov
2012-02-09 1:46 ` David Rientjes
2012-02-07 6:50 ` [PATCH 4/8] powerpc/mm: " Anton Vorontsov
2012-02-07 6:50 ` [PATCH 5/8] sh: " Anton Vorontsov
2012-02-07 6:50 ` [PATCH 6/8] blackfin: " Anton Vorontsov
2012-02-08 16:20 ` Oleg Nesterov
2012-02-07 6:51 ` [PATCH 7/8] um: Should hold tasklist_lock while traversing processes Anton Vorontsov
2012-02-07 6:51 ` [PATCH 8/8] um: Fix possible race on task->mm Anton Vorontsov
2012-02-08 15:59 ` [PATCH 0/8] Fixes for common mistakes w/ for_each_process and task->mm Oleg Nesterov
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