From: Anton Vorontsov <anton.vorontsov@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
user-mode-linux-devel@lists.sourceforge.net,
linux-sh@vger.kernel.org, Richard Weinberger <richard@nod.at>,
linux-kernel@vger.kernel.org,
uclinux-dist-devel@blackfin.uclinux.org, linux-mm@kvack.org,
Paul Mundt <lethal@linux-sh.org>,
John Stultz <john.stultz@linaro.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Russell King <linux@arm.linux.org.uk>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 09/10] um: Properly check all process' threads for a live mm
Date: Sat, 24 Mar 2012 14:31:10 +0400 [thread overview]
Message-ID: <20120324103110.GI29067@lizard> (raw)
In-Reply-To: <20120324102609.GA28356@lizard>
kill_off_processes() might miss a valid process, this is because
checking for process->mm is not enough. Process' main thread may
exit or detach its mm via use_mm(), but other threads may still
have a valid mm.
To catch this we use find_lock_task_mm(), which walks up all
threads and returns an appropriate task (with task lock held).
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/um/kernel/reboot.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 1411f4e..3d15243 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -6,6 +6,7 @@
#include "linux/sched.h"
#include "linux/spinlock.h"
#include "linux/slab.h"
+#include "linux/oom.h"
#include "kern_util.h"
#include "os.h"
#include "skas.h"
@@ -25,13 +26,13 @@ static void kill_off_processes(void)
read_lock(&tasklist_lock);
for_each_process(p) {
- task_lock(p);
- if (!p->mm) {
- task_unlock(p);
+ struct task_struct *t;
+
+ t = find_lock_task_mm(p);
+ if (!t)
continue;
- }
- pid = p->mm->context.id.u.pid;
- task_unlock(p);
+ pid = t->mm->context.id.u.pid;
+ task_unlock(t);
os_kill_ptraced_process(pid, 1);
}
read_unlock(&tasklist_lock);
--
1.7.9.2
next prev parent reply other threads:[~2012-03-24 10:32 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-24 10:26 [PATCH v2 0/10] Fixes for common mistakes w/ for_each_process and task->mm Anton Vorontsov
2012-03-24 10:27 ` [PATCH 01/10] cpu: Introduce clear_tasks_mm_cpumask() helper Anton Vorontsov
2012-03-24 12:43 ` Peter Zijlstra
2012-03-24 16:43 ` [PATCH v2.1 " Anton Vorontsov
2012-03-25 17:42 ` Oleg Nesterov
2012-03-26 7:59 ` Peter Zijlstra
2012-03-26 17:04 ` Oleg Nesterov
2012-03-26 17:23 ` Peter Zijlstra
2012-03-28 0:01 ` Benjamin Herrenschmidt
2012-03-24 10:28 ` [PATCH 02/10] arm: Use clear_tasks_mm_cpumask() Anton Vorontsov
2012-03-24 10:28 ` [PATCH 03/10] powerpc: " Anton Vorontsov
2012-03-24 10:28 ` [PATCH 04/10] sh: " Anton Vorontsov
2012-03-24 10:29 ` [PATCH 05/10] blackfin: A couple of task->mm handling fixes Anton Vorontsov
2012-03-24 10:30 ` [PATCH 06/10] blackfin: Fix possible deadlock in decode_address() Anton Vorontsov
2012-03-24 10:30 ` [PATCH 07/10] um: Should hold tasklist_lock while traversing processes Anton Vorontsov
2012-03-24 11:12 ` Richard Weinberger
2012-03-24 12:48 ` Peter Zijlstra
2012-03-24 16:43 ` Anton Vorontsov
2012-03-24 10:30 ` [PATCH 08/10] um: Fix possible race on task->mm Anton Vorontsov
2012-03-24 11:12 ` Richard Weinberger
2012-03-24 10:31 ` Anton Vorontsov [this message]
2012-03-24 11:12 ` [PATCH 09/10] um: Properly check all process' threads for a live mm Richard Weinberger
2012-03-24 10:31 ` [PATCH 10/10] oom: Make find_lock_task_mm() sparse-aware Anton Vorontsov
2012-03-24 12:52 ` Peter Zijlstra
2012-03-24 16:21 ` Anton Vorontsov
2012-03-24 16:43 ` Peter Zijlstra
2012-03-28 7:20 ` David Rientjes
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