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=-7.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED 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 62EC2C004C9 for ; Tue, 7 May 2019 18:12:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3348620825 for ; Tue, 7 May 2019 18:12:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="GZ/H3rR/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727168AbfEGSMQ (ORCPT ); Tue, 7 May 2019 14:12:16 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:2316 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726378AbfEGSMQ (ORCPT ); Tue, 7 May 2019 14:12:16 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 07 May 2019 11:12:23 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Tue, 07 May 2019 11:12:15 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Tue, 07 May 2019 11:12:15 -0700 Received: from rcampbell-dev.nvidia.com (172.20.13.39) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 May 2019 18:12:15 +0000 Subject: Re: [PATCH 4/5] mm/hmm: hmm_vma_fault() doesn't always call hmm_range_unregister() To: Souptick Joarder CC: Linux-MM , , John Hubbard , Ira Weiny , Dan Williams , Arnd Bergmann , Balbir Singh , Dan Carpenter , Matthew Wilcox , Andrew Morton References: <20190506232942.12623-1-rcampbell@nvidia.com> <20190506232942.12623-5-rcampbell@nvidia.com> From: Ralph Campbell Message-ID: Date: Tue, 7 May 2019 11:12:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1557252743; bh=4sryYpBiNg4XxjM8zLEdkqZ8Dj/ZnD7DO4AYpsXPphY=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=GZ/H3rR/FDVS4uZ/9gaPXJwIfOeK9Rc/JUQV331+m673Nrcdfxw9Ri+Pv003fgeT/ NnX9BCVqu86s9oVw8qBofRpZhewvm9GsINKZzZ8Cax3R0DFaui9YYJIfXGvh9DeUci aYDoX3nzO4jYeNxx2EtZYEy5wxuosyjMLorsS+vFOaoEMUlVuxiIqMh/LkqpmP4RVp aJ4gBG2V/AJzS5U0XxSkYNWAdQ/8h/idPLKj82lrCOynwUrcJgJZdsQON5OprxwU/M KwId2544mF3Ku5qM9XmHl6pAWwLBcdvVAIZDY0DS2dkJPFxHFiJlFguYJeH4Rlx//6 Q8i2Qus/oydqQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/7/19 6:15 AM, Souptick Joarder wrote: > On Tue, May 7, 2019 at 5:00 AM wrote: >> >> From: Ralph Campbell >> >> The helper function hmm_vma_fault() calls hmm_range_register() but is >> missing a call to hmm_range_unregister() in one of the error paths. >> This leads to a reference count leak and ultimately a memory leak on >> struct hmm. >> >> Always call hmm_range_unregister() if hmm_range_register() succeeded. > > How about * Call hmm_range_unregister() in error path if > hmm_range_register() succeeded* ? Sure, sounds good. I'll include that in v2. >> >> Signed-off-by: Ralph Campbell >> Cc: John Hubbard >> Cc: Ira Weiny >> Cc: Dan Williams >> Cc: Arnd Bergmann >> Cc: Balbir Singh >> Cc: Dan Carpenter >> Cc: Matthew Wilcox >> Cc: Souptick Joarder >> Cc: Andrew Morton >> --- >> include/linux/hmm.h | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/hmm.h b/include/linux/hmm.h >> index 35a429621e1e..fa0671d67269 100644 >> --- a/include/linux/hmm.h >> +++ b/include/linux/hmm.h >> @@ -559,6 +559,7 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block) >> return (int)ret; >> >> if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) { >> + hmm_range_unregister(range); >> /* >> * The mmap_sem was taken by driver we release it here and >> * returns -EAGAIN which correspond to mmap_sem have been >> @@ -570,13 +571,13 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block) >> >> ret = hmm_range_fault(range, block); >> if (ret <= 0) { >> + hmm_range_unregister(range); > > what is the reason to moved it up ? I moved it up because the normal calling pattern is: down_read(&mm->mmap_sem) hmm_vma_fault() hmm_range_register() hmm_range_fault() hmm_range_unregister() up_read(&mm->mmap_sem) I don't think it is a bug to unlock mmap_sem and then unregister, it is just more consistent nesting. >> if (ret == -EBUSY || !ret) { >> /* Same as above, drop mmap_sem to match old API. */ >> up_read(&range->vma->vm_mm->mmap_sem); >> ret = -EBUSY; >> } else if (ret == -EAGAIN) >> ret = -EBUSY; >> - hmm_range_unregister(range); >> return ret; >> } >> return 0; >> -- >> 2.20.1 >>