From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935943AbcIEQuU (ORCPT ); Mon, 5 Sep 2016 12:50:20 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52530 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934076AbcIEQuP (ORCPT ); Mon, 5 Sep 2016 12:50:15 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleg Nesterov , Johannes Weiner , Michal Hocko , Alexander Shishkin , Alexei Starovoitov , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Vladimir Davydov , Ingo Molnar Subject: [PATCH 4.7 054/143] uprobes: Fix the memcg accounting Date: Mon, 5 Sep 2016 18:43:50 +0200 Message-Id: <20160905164432.898218954@linuxfoundation.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160905164430.593075551@linuxfoundation.org> References: <20160905164430.593075551@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov commit 6c4687cc17a788a6dd8de3e27dbeabb7cbd3e066 upstream. __replace_page() wronlgy calls mem_cgroup_cancel_charge() in "success" path, it should only do this if page_check_address() fails. This means that every enable/disable leads to unbalanced mem_cgroup_uncharge() from put_page(old_page), it is trivial to underflow the page_counter->count and trigger OOM. Reported-and-tested-by: Brenden Blanco Signed-off-by: Oleg Nesterov Reviewed-by: Johannes Weiner Acked-by: Michal Hocko Cc: Alexander Shishkin Cc: Alexei Starovoitov Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vladimir Davydov Fixes: 00501b531c47 ("mm: memcontrol: rewrite charge API") Link: http://lkml.kernel.org/r/20160817153629.GB29724@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/events/uprobes.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -172,8 +172,10 @@ static int __replace_page(struct vm_area mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); err = -EAGAIN; ptep = page_check_address(page, mm, addr, &ptl, 0); - if (!ptep) + if (!ptep) { + mem_cgroup_cancel_charge(kpage, memcg, false); goto unlock; + } get_page(kpage); page_add_new_anon_rmap(kpage, vma, addr, false); @@ -200,7 +202,6 @@ static int __replace_page(struct vm_area err = 0; unlock: - mem_cgroup_cancel_charge(kpage, memcg, false); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); unlock_page(page); return err;