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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Yu Zhao <yuzhao@google.com>
Cc: Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: avoid slub allocation while holding list_lock
Date: Mon, 9 Sep 2019 19:00:52 +0300	[thread overview]
Message-ID: <20190909160052.cxpfdmnrqucsilz2@box> (raw)
In-Reply-To: <20190909061016.173927-1-yuzhao@google.com>

On Mon, Sep 09, 2019 at 12:10:16AM -0600, Yu Zhao wrote:
> If we are already under list_lock, don't call kmalloc(). Otherwise we
> will run into deadlock because kmalloc() also tries to grab the same
> lock.
> 
> Instead, allocate pages directly. Given currently page->objects has
> 15 bits, we only need 1 page. We may waste some memory but we only do
> so when slub debug is on.
> 
>   WARNING: possible recursive locking detected
>   --------------------------------------------
>   mount-encrypted/4921 is trying to acquire lock:
>   (&(&n->list_lock)->rlock){-.-.}, at: ___slab_alloc+0x104/0x437
> 
>   but task is already holding lock:
>   (&(&n->list_lock)->rlock){-.-.}, at: __kmem_cache_shutdown+0x81/0x3cb
> 
>   other info that might help us debug this:
>    Possible unsafe locking scenario:
> 
>          CPU0
>          ----
>     lock(&(&n->list_lock)->rlock);
>     lock(&(&n->list_lock)->rlock);
> 
>    *** DEADLOCK ***
> 
> Signed-off-by: Yu Zhao <yuzhao@google.com>

Looks sane to me:

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov

  reply	other threads:[~2019-09-09 16:00 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-09  6:10 [PATCH] mm: avoid slub allocation while holding list_lock Yu Zhao
2019-09-09 16:00 ` Kirill A. Shutemov [this message]
2019-09-09 20:57   ` Tetsuo Handa
2019-09-09 21:39     ` Yu Zhao
2019-09-10  1:41       ` Tetsuo Handa
2019-09-10  2:16         ` Yu Zhao
2019-09-10  9:16       ` Kirill A. Shutemov
2019-09-11 14:13 ` Andrew Morton
2019-09-12  0:29   ` [PATCH 1/3] mm: correct mask size for slub page->objects Yu Zhao
2019-09-12  0:29     ` [PATCH 2/3] mm: avoid slub allocation while holding list_lock Yu Zhao
2019-09-12  0:44       ` Kirill A. Shutemov
2019-09-12  1:31         ` Yu Zhao
2019-09-12  2:31         ` [PATCH v2 1/4] mm: correct mask size for slub page->objects Yu Zhao
2019-09-12  2:31           ` [PATCH v2 2/4] mm: clean up validate_slab() Yu Zhao
2019-09-12  9:46             ` Kirill A. Shutemov
2019-09-12  2:31           ` [PATCH v2 3/4] mm: avoid slub allocation while holding list_lock Yu Zhao
2019-09-12 10:04             ` Kirill A. Shutemov
2019-09-12  2:31           ` [PATCH v2 4/4] mm: lock slub page when listing objects Yu Zhao
2019-09-12 10:06             ` Kirill A. Shutemov
2019-09-12 21:12               ` Yu Zhao
2019-09-13 14:58             ` Christopher Lameter
2019-09-12  9:40           ` [PATCH v2 1/4] mm: correct mask size for slub page->objects Kirill A. Shutemov
2019-09-12 21:11             ` Yu Zhao
2019-09-12 22:03               ` Kirill A. Shutemov
2019-09-14  0:07           ` [PATCH v3 1/2] mm: clean up validate_slab() Yu Zhao
2019-09-14  0:07             ` [PATCH v3 2/2] mm: avoid slub allocation while holding list_lock Yu Zhao
2019-09-16  8:39             ` [PATCH v3 1/2] mm: clean up validate_slab() Kirill A. Shutemov
2019-11-08 19:39             ` [PATCH v4 " Yu Zhao
2019-11-08 19:39               ` [PATCH v4 2/2] mm: avoid slub allocation while holding list_lock Yu Zhao
2019-11-09 20:52                 ` Christopher Lameter
2019-11-09 23:01                   ` Yu Zhao
2019-11-09 23:16                     ` Christopher Lameter
2019-11-10 18:47                       ` Yu Zhao
2019-11-11 15:47                         ` Christopher Lameter
2019-11-11 15:55                           ` [FIX] slub: Remove kmalloc under list_lock from list_slab_objects() V2 Christopher Lameter
2019-11-30 23:09                             ` Andrew Morton
2019-12-01  1:17                               ` Tetsuo Handa
2019-12-02 15:12                               ` Christopher Lameter
2019-12-07 22:03                                 ` Yu Zhao
2020-01-10 14:11                                   ` Vlastimil Babka
2020-01-12 11:03                                     ` Tetsuo Handa
2020-01-13  1:34                                       ` Christopher Lameter
2019-11-11 18:15                           ` [PATCH v4 2/2] mm: avoid slub allocation while holding list_lock Shakeel Butt
2019-09-12  0:29     ` [PATCH 3/3] mm: lock slub page when listing objects Yu Zhao

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