| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <48D2CD1D.9040202@gmail.com>
Date: Thu, 18 Sep 2008 23:50:21 +0200
From: Andrea Righi <righi.andrea@...il.com>
To: Balbir Singh <balbir@...ux.vnet.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Paul Menage <menage@...gle.com>,
containers@...ts.linux-foundation.org, linux-mm@...ck.org,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH -mm] memrlimit: fix task_lock() recursive locking (v2)
cgroup_mm_owner_callbacks() can be called with task_lock() held in
mm_update_next_owner(), and all the .mm_owner_changed callbacks seem to
be *always* called with task_lock() held.
Actually, memrlimit is using task_lock() via get_task_mm() in
memrlimit_cgroup_mm_owner_changed(), raising the following recursive locking
trace:
[ 5346.421365] =============================================
[ 5346.421374] [ INFO: possible recursive locking detected ]
[ 5346.421381] 2.6.27-rc5-mm1 #20
[ 5346.421385] ---------------------------------------------
[ 5346.421391] interbench/10530 is trying to acquire lock:
[ 5346.421396] (&p->alloc_lock){--..}, at: [<ffffffff8023b034>] get_task_mm+0x24/0x70
[ 5346.421417]
[ 5346.421418] but task is already holding lock:
[ 5346.421423] (&p->alloc_lock){--..}, at: [<ffffffff8023db98>] mm_update_next_owner+0x148/0x230
[ 5346.421438]
[ 5346.421440] other info that might help us debug this:
[ 5346.421446] 2 locks held by interbench/10530:
[ 5346.421450] #0: (&mm->mmap_sem){----}, at: [<ffffffff8023db90>] mm_update_next_owner+0x140/0x230
[ 5346.421467] #1: (&p->alloc_lock){--..}, at: [<ffffffff8023db98>] mm_update_next_owner+0x148/0x230
[ 5346.421483]
[ 5346.421485] stack backtrace:
[ 5346.421491] Pid: 10530, comm: interbench Not tainted 2.6.27-rc5-mm1 #20
[ 5346.421496] Call Trace:
[ 5346.421507] [<ffffffff80263383>] validate_chain+0xb03/0x10d0
[ 5346.421515] [<ffffffff80263c05>] __lock_acquire+0x2b5/0x9c0
[ 5346.421522] [<ffffffff80262cc2>] validate_chain+0x442/0x10d0
[ 5346.421530] [<ffffffff802643aa>] lock_acquire+0x9a/0xe0
[ 5346.421537] [<ffffffff8023b034>] get_task_mm+0x24/0x70
[ 5346.421546] [<ffffffff804757c7>] _spin_lock+0x37/0x70
[ 5346.421553] [<ffffffff8023b034>] get_task_mm+0x24/0x70
[ 5346.421560] [<ffffffff8023b034>] get_task_mm+0x24/0x70
[ 5346.421569] [<ffffffff802b91f8>] memrlimit_cgroup_mm_owner_changed+0x18/0x90
[ 5346.421579] [<ffffffff80278b03>] cgroup_mm_owner_callbacks+0x93/0xc0
[ 5346.421587] [<ffffffff8023dc36>] mm_update_next_owner+0x1e6/0x230
[ 5346.421595] [<ffffffff8023dd72>] exit_mm+0xf2/0x120
[ 5346.421602] [<ffffffff8023f547>] do_exit+0x167/0x930
[ 5346.421610] [<ffffffff8047604a>] _spin_unlock_irq+0x2a/0x50
[ 5346.421618] [<ffffffff8023fd46>] do_group_exit+0x36/0xa0
[ 5346.421626] [<ffffffff8020b7cb>] system_call_fastpath+0x16/0x1b
Since we hold task_lock(), we know that p->mm cannot change and we don't have
to worry about incrementing mm_users. So, just use p->mm directly and
check that we've not picked a kernel thread.
Signed-off-by: Andrea Righi <righi.andrea@...il.com>
---
kernel/cgroup.c | 3 ++-
mm/memrlimitcgroup.c | 10 ++++------
2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 678a680..03cc925 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2757,7 +2757,8 @@ void cgroup_fork_callbacks(struct task_struct *child)
* invoke this routine, since it assigns the mm->owner the first time
* and does not change it.
*
- * The callbacks are invoked with mmap_sem held in read mode.
+ * The callbacks are invoked with task_lock held and mmap_sem held in read
+ * mode.
*/
void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
{
diff --git a/mm/memrlimitcgroup.c b/mm/memrlimitcgroup.c
index 8ee74f6..b3d20f5 100644
--- a/mm/memrlimitcgroup.c
+++ b/mm/memrlimitcgroup.c
@@ -238,7 +238,7 @@ out:
}
/*
- * This callback is called with mmap_sem held
+ * This callback is called with mmap_sem and task_lock held
*/
static void memrlimit_cgroup_mm_owner_changed(struct cgroup_subsys *ss,
struct cgroup *old_cgrp,
@@ -246,9 +246,9 @@ static void memrlimit_cgroup_mm_owner_changed(struct cgroup_subsys *ss,
struct task_struct *p)
{
struct memrlimit_cgroup *memrcg, *old_memrcg;
- struct mm_struct *mm = get_task_mm(p);
+ struct mm_struct *mm = p->mm;
- BUG_ON(!mm);
+ BUG_ON(!mm || (p->flags & PF_KTHREAD));
/*
* If we don't have a new cgroup, we just uncharge from the old one.
@@ -258,7 +258,7 @@ static void memrlimit_cgroup_mm_owner_changed(struct cgroup_subsys *ss,
memrcg = memrlimit_cgroup_from_cgrp(cgrp);
if (res_counter_charge(&memrcg->as_res,
mm->total_vm << PAGE_SHIFT))
- goto out;
+ return;
}
if (old_cgrp) {
@@ -266,8 +266,6 @@ static void memrlimit_cgroup_mm_owner_changed(struct cgroup_subsys *ss,
res_counter_uncharge(&old_memrcg->as_res,
mm->total_vm << PAGE_SHIFT);
}
-out:
- mmput(mm);
}
struct cgroup_subsys memrlimit_cgroup_subsys = {
--
1.5.4.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists