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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 14B05C433E7 for ; Fri, 16 Oct 2020 02:44:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8649120B1F for ; Fri, 16 Oct 2020 02:44:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="V537auYg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8649120B1F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 195E894001F; Thu, 15 Oct 2020 22:44:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 11FEC940007; Thu, 15 Oct 2020 22:44:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 05C0194001F; Thu, 15 Oct 2020 22:44:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0057.hostedemail.com [216.40.44.57]) by kanga.kvack.org (Postfix) with ESMTP id CA624940007 for ; Thu, 15 Oct 2020 22:44:34 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 703151EE6 for ; Fri, 16 Oct 2020 02:44:34 +0000 (UTC) X-FDA: 77376245268.11.quilt85_050d0a627219 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 445E4180F8B81 for ; Fri, 16 Oct 2020 02:44:34 +0000 (UTC) X-HE-Tag: quilt85_050d0a627219 X-Filterd-Recvd-Size: 2954 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 02:44:33 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CF0120897; Fri, 16 Oct 2020 02:44:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602816273; bh=WHqzbeJL+Jv9AbqA81ataw2zRaw3cad4mqJGc/VcSRs=; h=Date:From:To:Subject:In-Reply-To:From; b=V537auYgSXNDtLL2qe4T/f5looRQqBnSWhntAdMtKuJEEUKrhVLChOiQJpHlbncim HEr7xvteF3xLkOopvHYm8jOB7sWBj+8qEwiBVUlojoFRzoLYhPqjKOQNxQ+NoP7pEg yg5QxQsteSy4fjTmbiYOEQsotJNaCwsF2fiVgk2s= Date: Thu, 15 Oct 2020 19:44:31 -0700 From: Andrew Morton To: akpm@linux-foundation.org, christian.koenig@amd.com, hch@lst.de, jannh@google.com, jgg@nvidia.com, jhubbard@nvidia.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 058/156] mm/mmu_notifier: fix mmget() assert in __mmu_interval_notifier_insert Message-ID: <20201016024431.w2DQBMSrK%akpm@linux-foundation.org> In-Reply-To: <20201015192732.f448da14e9854c7cb7299956@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: =46rom: Jann Horn Subject: mm/mmu_notifier: fix mmget() assert in __mmu_interval_notifier_ins= ert The comment talks about having to hold mmget() (which means mm_users), but the actual check is on mm_count (which would be mmgrab()). Given that MMU notifiers are torn down in mmput() -> __mmput() -> exit_mmap() -> mmu_notifier_release(), I believe that the comment is correct and the check should be on mm->mm_users. Fix it up accordingly. Link: https://lkml.kernel.org/r/20200901000143.207585-1-jannh@google.com Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier") Signed-off-by: Jann Horn Reviewed-by: Jason Gunthorpe Cc: John Hubbard Cc: Christoph Hellwig Cc: Christian K=C3=B6nig --- mm/mmu_notifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/mmu_notifier.c~mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_= notifier_insert +++ a/mm/mmu_notifier.c @@ -913,7 +913,7 @@ static int __mmu_interval_notifier_inser return -EOVERFLOW; =20 /* Must call with a mmget() held */ - if (WARN_ON(atomic_read(&mm->mm_count) <=3D 0)) + if (WARN_ON(atomic_read(&mm->mm_users) <=3D 0)) return -EINVAL; =20 /* pairs with mmdrop in mmu_interval_notifier_remove() */ _