From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75852C433FE for ; Thu, 16 Sep 2021 17:51:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C3CE60EE3 for ; Thu, 16 Sep 2021 17:51:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356199AbhIPRt1 (ORCPT ); Thu, 16 Sep 2021 13:49:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:57070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355377AbhIPRlY (ORCPT ); Thu, 16 Sep 2021 13:41:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 69ACF6325A; Thu, 16 Sep 2021 16:52:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1631811157; bh=95b3wlf+FrA0gjk15GOSQxUqJm1hscPLiRT5Brty8DQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=asd385txsyANNJOUNGDiRao4T24Hyu8dYbS7EWXr5m912+1Rkc5mRy5rwGWYjnr1r Ww4TwyTAyW9QoxJENi0QQrWIbZ0Ne5If6urjx2LvkQS11aGJsFdpV+JRVTw6cXSPcF gehP1W8N49w7bXUcGA63Jx2ihG37YSbokC4LJHGc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Kravetz , Guillaume Morin , Andrew Morton , Linus Torvalds Subject: [PATCH 5.14 403/432] hugetlb: fix hugetlb cgroup refcounting during vma split Date: Thu, 16 Sep 2021 18:02:32 +0200 Message-Id: <20210916155824.490316776@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210916155810.813340753@linuxfoundation.org> References: <20210916155810.813340753@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mike Kravetz commit 09a26e832705fdb7a9484495b71a05e0bbc65207 upstream. Guillaume Morin reported hitting the following WARNING followed by GPF or NULL pointer deference either in cgroups_destroy or in the kill_css path.: percpu ref (css_release) <= 0 (-1) after switching to atomic WARNING: CPU: 23 PID: 130 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x127/0x130 CPU: 23 PID: 130 Comm: ksoftirqd/23 Kdump: loaded Tainted: G O 5.10.60 #1 RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x127/0x130 Call Trace: rcu_core+0x30f/0x530 rcu_core_si+0xe/0x10 __do_softirq+0x103/0x2a2 run_ksoftirqd+0x2b/0x40 smpboot_thread_fn+0x11a/0x170 kthread+0x10a/0x140 ret_from_fork+0x22/0x30 Upon further examination, it was discovered that the css structure was associated with hugetlb reservations. For private hugetlb mappings the vma points to a reserve map that contains a pointer to the css. At mmap time, reservations are set up and a reference to the css is taken. This reference is dropped in the vma close operation; hugetlb_vm_op_close. However, if a vma is split no additional reference to the css is taken yet hugetlb_vm_op_close will be called twice for the split vma resulting in an underflow. Fix by taking another reference in hugetlb_vm_op_open. Note that the reference is only taken for the owner of the reserve map. In the more common fork case, the pointer to the reserve map is cleared for non-owning vmas. Link: https://lkml.kernel.org/r/20210830215015.155224-1-mike.kravetz@oracle.com Fixes: e9fe92ae0cd2 ("hugetlb_cgroup: add reservation accounting for private mappings") Signed-off-by: Mike Kravetz Reported-by: Guillaume Morin Suggested-by: Guillaume Morin Tested-by: Guillaume Morin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/hugetlb_cgroup.h | 12 ++++++++++++ mm/hugetlb.c | 4 +++- 2 files changed, 15 insertions(+), 1 deletion(-) --- a/include/linux/hugetlb_cgroup.h +++ b/include/linux/hugetlb_cgroup.h @@ -121,6 +121,13 @@ static inline void hugetlb_cgroup_put_rs css_put(&h_cg->css); } +static inline void resv_map_dup_hugetlb_cgroup_uncharge_info( + struct resv_map *resv_map) +{ + if (resv_map->css) + css_get(resv_map->css); +} + extern int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages, struct hugetlb_cgroup **ptr); extern int hugetlb_cgroup_charge_cgroup_rsvd(int idx, unsigned long nr_pages, @@ -199,6 +206,11 @@ static inline void hugetlb_cgroup_put_rs { } +static inline void resv_map_dup_hugetlb_cgroup_uncharge_info( + struct resv_map *resv_map) +{ +} + static inline int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages, struct hugetlb_cgroup **ptr) { --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4033,8 +4033,10 @@ static void hugetlb_vm_op_open(struct vm * after this open call completes. It is therefore safe to take a * new reference here without additional locking. */ - if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + resv_map_dup_hugetlb_cgroup_uncharge_info(resv); kref_get(&resv->refs); + } } static void hugetlb_vm_op_close(struct vm_area_struct *vma)