From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:54118 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753351AbdHTSdM (ORCPT ); Sun, 20 Aug 2017 14:33:12 -0400 Subject: Patch "slub: fix per memcg cache leak on css offline" has been added to the 4.12-stable tree To: vdavydov.dev@gmail.com, akpm@linux-foundation.org, avagin@gmail.com, cl@linux.com, gregkh@linuxfoundation.org, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, mhocko@kernel.org, penberg@kernel.org, rientjes@google.com, tj@kernel.org, torvalds@linux-foundation.org Cc: , From: Date: Sun, 20 Aug 2017 11:33:09 -0700 Message-ID: <150325398913671@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled slub: fix per memcg cache leak on css offline to the 4.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: slub-fix-per-memcg-cache-leak-on-css-offline.patch and it can be found in the queue-4.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From f6ba488073fe8159851fe398cc3c5ee383bb4c7a Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Fri, 18 Aug 2017 15:16:08 -0700 Subject: slub: fix per memcg cache leak on css offline From: Vladimir Davydov commit f6ba488073fe8159851fe398cc3c5ee383bb4c7a upstream. To avoid a possible deadlock, sysfs_slab_remove() schedules an asynchronous work to delete sysfs entries corresponding to the kmem cache. To ensure the cache isn't freed before the work function is called, it takes a reference to the cache kobject. The reference is supposed to be released by the work function. However, the work function (sysfs_slab_remove_workfn()) does nothing in case the cache sysfs entry has already been deleted, leaking the kobject and the corresponding cache. This may happen on a per memcg cache destruction, because sysfs entries of a per memcg cache are deleted on memcg offline if the cache is empty (see __kmemcg_cache_deactivate()). The kmemleak report looks like this: unreferenced object 0xffff9f798a79f540 (size 32): comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.554s) hex dump (first 32 bytes): 6b 6d 61 6c 6c 6f 63 2d 31 36 28 31 35 39 39 3a kmalloc-16(1599: 6e 65 77 72 6f 6f 74 29 00 23 6b c0 ff ff ff ff newroot).#k..... backtrace: kmemleak_alloc+0x4a/0xa0 __kmalloc_track_caller+0x148/0x2c0 kvasprintf+0x66/0xd0 kasprintf+0x49/0x70 memcg_create_kmem_cache+0xe6/0x160 memcg_kmem_cache_create_func+0x20/0x110 process_one_work+0x205/0x5d0 worker_thread+0x4e/0x3a0 kthread+0x109/0x140 ret_from_fork+0x2a/0x40 unreferenced object 0xffff9f79b6136840 (size 416): comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.573s) hex dump (first 32 bytes): 40 fb 80 c2 3e 33 00 00 00 00 00 40 00 00 00 00 @...>3.....@.... 00 00 00 00 00 00 00 00 10 00 00 00 10 00 00 00 ................ backtrace: kmemleak_alloc+0x4a/0xa0 kmem_cache_alloc+0x128/0x280 create_cache+0x3b/0x1e0 memcg_create_kmem_cache+0x118/0x160 memcg_kmem_cache_create_func+0x20/0x110 process_one_work+0x205/0x5d0 worker_thread+0x4e/0x3a0 kthread+0x109/0x140 ret_from_fork+0x2a/0x40 Fix the leak by adding the missing call to kobject_put() to sysfs_slab_remove_workfn(). Link: http://lkml.kernel.org/r/20170812181134.25027-1-vdavydov.dev@gmail.com Fixes: 3b7b314053d02 ("slub: make sysfs file removal asynchronous") Signed-off-by: Vladimir Davydov Reported-by: Andrei Vagin Tested-by: Andrei Vagin Acked-by: Tejun Heo Acked-by: David Rientjes Cc: Michal Hocko Cc: Johannes Weiner Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/slub.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -5637,13 +5637,14 @@ static void sysfs_slab_remove_workfn(str * A cache is never shut down before deactivation is * complete, so no need to worry about synchronization. */ - return; + goto out; #ifdef CONFIG_MEMCG kset_unregister(s->memcg_kset); #endif kobject_uevent(&s->kobj, KOBJ_REMOVE); kobject_del(&s->kobj); +out: kobject_put(&s->kobj); } Patches currently in stable-queue which might be from vdavydov.dev@gmail.com are queue-4.12/slub-fix-per-memcg-cache-leak-on-css-offline.patch