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
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 9 May 2012 09:34:24 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	Andrey Vagin <avagin@...nvz.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: lockdep reports about recursive locking in kmemleak

On Mon, Apr 30, 2012 at 2:04 PM, Catalin Marinas
<catalin.marinas@....com> wrote:
> On Fri, Apr 27, 2012 at 12:30:36PM +0100, Andrey Vagin wrote:
>> I found a following message in dmesg. Probably we should to do something
>> similar as for debug_objects, it sets own class for parent->list_lock.
>> Does anyone want to fix that?
>>
>> =============================================
>> [ INFO: possible recursive locking detected ]
>> 3.3.0+ #87 Not tainted
>> ---------------------------------------------
>> udevd/847 is trying to acquire lock:
>>   (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff811783f1>]
>> cache_alloc_refill+0xa1/0x300
>>
>> but task is already holding lock:
>>   (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff81177628>]
>> cache_flusharray+0x68/0x180
>>
>> other info that might help us debug this:
>>   Possible unsafe locking scenario:
>>
>>         CPU0
>>         ----
>>    lock(&(&parent->list_lock)->rlock);
>>    lock(&(&parent->list_lock)->rlock);
>>
>>   *** DEADLOCK ***
>>
>>   May be due to missing lock nesting notation
>>
>> 1 lock held by udevd/847:
>>   #0:  (&(&parent->list_lock)->rlock){-.-...}, at: [<ffffffff81177628>]
>> cache_flusharray+0x68/0x180
>
> I'm not sure what the right fix is (cc'ing Christoph for the slab.c
> code). The lockdep warning is not in kmemleak, it just happens that
> cache_flusharray() (holding an l3->list_lock) triggers a new allocation
> via debug_object_activate() and kmemleak also tries to allocate its
> metadata, causing a cache_alloc_refill() call which acquires a
> different l3->list_lock, hence the lockdep warning.

How do we know it's always a different nodelist ("l3")?

> Below is a quick fix but I don't know whether it could hide a real
> problem in the future:
>
> diff --git a/mm/slab.c b/mm/slab.c
> index e901a36..3d2bfc6 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3143,7 +3143,7 @@ retry:
>        l3 = cachep->nodelists[node];
>
>        BUG_ON(ac->avail > 0 || !l3);
> -       spin_lock(&l3->list_lock);
> +       spin_lock_nested(&l3->list_lock, SINGLE_DEPTH_NESTING);
>
>        /* See if we can refill from the shared array */
>        if (l3->shared && transfer_objects(ac, l3->shared, batchcount)) {
>
>
> I'm leaving the original stack trace below for reference.

Lockdep and slab... I'm CC'ing Peter (sorry!) :-)

>> stack backtrace:
>> Pid: 847, comm: udevd Not tainted 3.3.0+ #87
>> Call Trace:
>>   [<ffffffff810b835a>] __lock_acquire+0x126a/0x1730
>>   [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
>>   [<ffffffff810b88d1>] lock_acquire+0xb1/0x1a0
>>   [<ffffffff811783f1>] ? cache_alloc_refill+0xa1/0x300
>>   [<ffffffff8118cdb9>] ? create_object+0x39/0x2e0
>>   [<ffffffff8153a141>] _raw_spin_lock+0x41/0x50
>>   [<ffffffff811783f1>] ? cache_alloc_refill+0xa1/0x300
>>   [<ffffffff811783f1>] cache_alloc_refill+0xa1/0x300
>>   [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
>>   [<ffffffff8118cdb9>] ? create_object+0x39/0x2e0
>>   [<ffffffff81179cbc>] kmem_cache_alloc+0x2cc/0x320
>>   [<ffffffff8118cdb9>] create_object+0x39/0x2e0
>>   [<ffffffff810b73f2>] ? __lock_acquire+0x302/0x1730
>>   [<ffffffff8151fade>] kmemleak_alloc+0x5e/0xc0
>>   [<ffffffff81179b2c>] kmem_cache_alloc+0x13c/0x320
>>   [<ffffffff81294d99>] __debug_object_init+0x3b9/0x3d0
>>   [<ffffffff812944fa>] ? debug_object_activate+0xca/0x190
>>   [<ffffffff81294dff>] debug_object_init+0x1f/0x30
>>   [<ffffffff810767d7>] rcuhead_fixup_activate+0x27/0x70
>>   [<ffffffff81293d35>] debug_object_fixup+0x15/0x20
>>   [<ffffffff8129450c>] debug_object_activate+0xdc/0x190
>>   [<ffffffff81177b50>] ? kmem_cache_shrink+0x70/0x70
>>   [<ffffffff810f0d12>] __call_rcu+0x42/0x1e0
>>   [<ffffffff810f0ee5>] call_rcu_sched+0x15/0x20
>>   [<ffffffff81177113>] slab_destroy+0x153/0x160
>>   [<ffffffff81177628>] ? cache_flusharray+0x68/0x180
>>   [<ffffffff81177179>] free_block+0x59/0x230
>>   [<ffffffff81177655>] cache_flusharray+0x95/0x180
>>   [<ffffffff81176dbf>] ? kmem_cache_free+0x11f/0x320
>>   [<ffffffff81176f6c>] kmem_cache_free+0x2cc/0x320
>>   [<ffffffff8115b5b1>] ? __put_anon_vma+0x61/0xb0
>>   [<ffffffff8115b5b1>] __put_anon_vma+0x61/0xb0
>>   [<ffffffff8115bb8b>] unlink_anon_vmas+0x13b/0x1a0
>>   [<ffffffff8114fac1>] free_pgtables+0x91/0x120
>>   [<ffffffff81156101>] exit_mmap+0xb1/0x120
>>   [<ffffffff8104e24b>] mmput+0x7b/0x120
>>   [<ffffffff81053d68>] exit_mm+0x108/0x130
>>   [<ffffffff8153aa70>] ? _raw_spin_unlock_irq+0x30/0x50
>>   [<ffffffff81056277>] do_exit+0x167/0x970
>>   [<ffffffff811b36c3>] ? mntput+0x23/0x40
>>   [<ffffffff81192f6d>] ? fput+0x1ad/0x280
>>   [<ffffffff8153ae59>] ? retint_swapgs+0x13/0x1b
>>   [<ffffffff81056adb>] do_group_exit+0x5b/0xd0
>>   [<ffffffff81056b67>] sys_exit_group+0x17/0x20
>>   [<ffffffff81543729>] system_call_fastpath+0x16/0x1b
> --
> 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/
--
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