From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752304AbdLBPwL (ORCPT ); Sat, 2 Dec 2017 10:52:11 -0500 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:6699 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752194AbdLBPwD (ORCPT ); Sat, 2 Dec 2017 10:52:03 -0500 From: alexander.levin@verizon.com Cc: Miles Chen , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linus Torvalds , alexander.levin@verizon.com X-Host: mariner.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.14 30/64] slub: fix sysfs duplicate filename creation when slub_debug=O Thread-Topic: [PATCH AUTOSEL for 4.14 30/64] slub: fix sysfs duplicate filename creation when slub_debug=O Thread-Index: AQHTa4VpAy1HmqC+LUCgE1TEFtVaRA== Date: Sat, 2 Dec 2017 15:51:27 +0000 Message-ID: <20171202155101.7573-30-alexander.levin@verizon.com> References: <20171202155101.7573-1-alexander.levin@verizon.com> In-Reply-To: <20171202155101.7573-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vB2GLFvZ030072 From: Miles Chen [ Upstream commit 11066386efa692f77171484c32ea30f6e5a0d729 ] When slub_debug=O is set. It is possible to clear debug flags for an "unmergeable" slab cache in kmem_cache_open(). It makes the "unmergeable" cache became "mergeable" in sysfs_slab_add(). These caches will generate their "unique IDs" by create_unique_id(), but it is possible to create identical unique IDs. In my experiment, sgpool-128, names_cache, biovec-256 generate the same ID ":Ft-0004096" and the kernel reports "sysfs: cannot create duplicate filename '/kernel/slab/:Ft-0004096'". To repeat my experiment, set disable_higher_order_debug=1, CONFIG_SLUB_DEBUG_ON=y in kernel-4.14. Fix this issue by setting unmergeable=1 if slub_debug=O and the the default slub_debug contains any no-merge flags. call path: kmem_cache_create() __kmem_cache_alias() -> we set SLAB_NEVER_MERGE flags here create_cache() __kmem_cache_create() kmem_cache_open() -> clear DEBUG_METADATA_FLAGS sysfs_slab_add() -> the slab cache is mergeable now sysfs: cannot create duplicate filename '/kernel/slab/:Ft-0004096' ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x60/0x7c Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.14.0-rc7ajb-00131-gd4c2e9f-dirty #123 Hardware name: linux,dummy-virt (DT) task: ffffffc07d4e0080 task.stack: ffffff8008008000 PC is at sysfs_warn_dup+0x60/0x7c LR is at sysfs_warn_dup+0x60/0x7c pc : lr : pstate: 60000145 Call trace: sysfs_warn_dup+0x60/0x7c sysfs_create_dir_ns+0x98/0xa0 kobject_add_internal+0xa0/0x294 kobject_init_and_add+0x90/0xb4 sysfs_slab_add+0x90/0x200 __kmem_cache_create+0x26c/0x438 kmem_cache_create+0x164/0x1f4 sg_pool_init+0x60/0x100 do_one_initcall+0x38/0x12c kernel_init_freeable+0x138/0x1d4 kernel_init+0x10/0xfc ret_from_fork+0x10/0x18 Link: http://lkml.kernel.org/r/1510365805-5155-1-git-send-email-miles.chen@mediatek.com Signed-off-by: Miles Chen Acked-by: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/slub.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index 1efbb8123037..8e1c027a30f4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5704,6 +5704,10 @@ static int sysfs_slab_add(struct kmem_cache *s) return 0; } + if (!unmergeable && disable_higher_order_debug && + (slub_debug & DEBUG_METADATA_FLAGS)) + unmergeable = 1; + if (unmergeable) { /* * Slabcache can never be merged so we can use the name proper. -- 2.11.0