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=-5.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,USER_AGENT_MUTT autolearn=ham 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 3FDD8C28CC7 for ; Mon, 10 Jun 2019 13:58:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 103452085A for ; Mon, 10 Jun 2019 13:58:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560175106; bh=CA2Amc9MdvcnMm3DA7gLp4cx2q2YaXDfXILVqwHIMMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=M5dWtWH733ZfqEsyA/crkIZ1Dg+1oHUJa5A9y/1eXd1yvOxB98mlnmN/n9VwT1ito GIyT/g/TrYkUd4eu5mcHbwmpbrh7gNlfpL/UWut/OOlC1KUUp+UF0ZPMHhyyfqe+Rc 33cDhooPsKUlBv7rnDSVr6/o4hJIt1haeGGzC2DI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390335AbfFJN6Z (ORCPT ); Mon, 10 Jun 2019 09:58:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:33234 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2389373AbfFJN6Z (ORCPT ); Mon, 10 Jun 2019 09:58:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2EFEDABD2; Mon, 10 Jun 2019 13:58:24 +0000 (UTC) Date: Mon, 10 Jun 2019 15:58:23 +0200 From: Michal Hocko To: Stable tree Cc: Greg KH , linux-mm@kvack.org, LKML , Andrea Arcangeli , Jann Horn , Oleg Nesterov , Peter Xu , Mike Rapoport , Jason Gunthorpe , Andrew Morton , Linus Torvalds , Joel Fernandes Subject: Re: [PATCH stable 4.4 v2] coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping Message-ID: <20190610135823.GI30967@dhcp22.suse.cz> References: <20190604094953.26688-1-mhocko@kernel.org> <20190610074635.2319-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190610074635.2319-1-mhocko@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Just a heads up. Ajay Kaher has noticed that mlx4 driver is missing the check in 4.14 [1] and 4.4 seems to have the same problem. I will wait for more review before reposting v3. The incremental diff is: diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c index 67c4c73343d4..6968154a073e 100644 --- a/drivers/infiniband/hw/mlx4/main.c +++ b/drivers/infiniband/hw/mlx4/main.c @@ -1042,6 +1042,8 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext) * mlx4_ib_vma_close(). */ down_write(&owning_mm->mmap_sem); + if (!mmget_still_valid(owning_mm)) + goto skip_mm; for (i = 0; i < HW_BAR_COUNT; i++) { vma = context->hw_bar_info[i].vma; if (!vma) @@ -1061,6 +1063,7 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext) context->hw_bar_info[i].vma->vm_ops = NULL; } +skip_mm: up_write(&owning_mm->mmap_sem); mmput(owning_mm); put_task_struct(owning_process); -- Michal Hocko SUSE Labs