From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5F8A7606A33A for ; Tue, 27 Oct 2026 08:51:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cLX5cty9 Received: by kanga.kvack.org (Postfix) id 48C0C6B0635; Tue, 27 Oct 2026 04:51:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 463576B0637; Tue, 27 Oct 2026 04:51:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 352D36B0638; Tue, 27 Oct 2026 04:51:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0A2696B0635 for ; Tue, 27 Oct 2026 04:51:07 -0400 (EDT) Received: from smtpin23.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 7E7D61609A3 for ; Tue, 27 Oct 2026 08:51:06 +0000 (UTC) X-FDA: 85367786532.23.7FEF119 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf03.hostedemail.com (Postfix) with ESMTP id DFCAD20005 for ; Tue, 27 Oct 2026 08:51:04 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=cLX5cty9; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793091064; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=lc0U5Ze+hBCT9T6cAf8QTcqfqTu5UwDLhLRH+Lp9NjM=; b=kEJ9wk6usjd0U0GfAx5LT1sI7X7L1xv9aj0IMxQig7ZFn9rQBOn7XUSqLlYfwDwCkcUrdK bkrX0hGZDzjqCnbH+qTE+SiwbQog05f3cVTbAXuIXw9KsmbPAa6HXrTiqzpUU7Si76/9vP egnjxJL5r8nWF0CNe+2wnZFSz8n3Av8= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=cLX5cty9; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793091064; b=xuxJUkiGtQfJ4pL6DMpYd2iIp7CJWhQWYRk0vXxnqDhN8p0KgAW03kKbSnj2LhM3KGe5E0 IlwInJTOAsa8ASzJU7rvdd6IoVv1weVeNVcuNWbPP5z1RqU+SNko/E096CdXurLYdXIPj2 iq5ecTtPvcrf9OO6bpfDwtRUCL1/Vas= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 54517601F9; Tue, 27 Oct 2026 08:51:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 370ED1F01825; Tue, 27 Oct 2026 08:50:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793091064; bh=lc0U5Ze+hBCT9T6cAf8QTcqfqTu5UwDLhLRH+Lp9NjM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=cLX5cty9Fes4nyGOhdTXTwUi4CjHh2d6Exjv+rOUNmJ1hOpq301ah/59VYJa3KAfa 0JAFnIYv5q6uCZJiWZ7/JnzC3pOPhPL5VdEq05fzYEQAfU8x5PjoaLGCbo4oJkSshy aEyuswfa3kOJCEFW345rfcWjsyhvaijqqaHgik6uB7QOrxdB7sJV1oJ6I3Q0c1V+Ry Cf3Ekq4j3MW2BWPpctWVOXD4r4MRy4tI0wpG7A71nGLVk4q5d74j9EcT8h6eyujZ5T xnvfCFG95f/Qz4H2P0ATu2ppTZylFpdC3r3f636dunxIG7AvtZ7dC6rCzDfglAN4g9 pK7u8ZerdMAkQ== Date: Tue, 27 Oct 2026 08:50:46 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Chris Mason , stable@vger.kernel.org Subject: Re: [PATCH 28/46] mm/mmu_notifier: set ->mm only after mmgrab() Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-28-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-28-6f74bec9a5bb@kernel.org> X-Rspamd-Queue-Id: DFCAD20005 X-Stat-Signature: 5617u7t5f6d7r7984oenjbt5k5urmjxb X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-16.1 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_PASS, SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793091064-280901 X-HE-Meta: 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 TZBNkNLV C9kwn/lVPnTVXRpSfQGd3Zg94jDARv8ed7JRmJVMRlkqU10BmG0oSDbrUEU0726jiigA2DXEni+3p/PYUO93Qwu4kirxnjkSRGTxP8Q5QwqAE5nEUDNPk67wIyFuoV1CphDmfhoilR2EziKUyohyJa1Em1qBXRw2Dzz39wGAQziFlJjjdSYYHo9T2T2KxlfuTiCceFP9muuSMrVdjyNBraRRmvymhTrQeTzAl6NeVjfD+vjLHk01bL8JhXxwY826b00bZF2adFvzM9tWtx6H70WpCpINQrSP/1S4DY5rU9ypntLG6ArT2Gg0JhfulDJV0+ERqMJrHRUc+0yb/9jrSABJtOprmFG3jrFyq3AFDNexU+nqSe5Dccejp3kI7cQQu+UXwIewbXSjJ6eM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 27, 2026 at 12:17:48AM +0100, David Hildenbrand (Arm) wrote: > From: Chris Mason > > Radeon uses a non-NULL notifier->mm to decide whether to call > mmu_interval_notifier_remove() when freeing a buffer object. > __mmu_interval_notifier_insert() sets ->mm before validating the range, > so a wrapping userptr range can leave ->mm set after insertion fails. > Cleanup then tries to remove an unregistered notifier for which no mm > reference was acquired. > > Set ->mm only after mmgrab(), once insertion can no longer fail. While > we could fix radeon's code instead, setting ->mm on success only makes > the code more robust. > > Fix generated by an LLM and sent by Chris Mason in private. > > Fixes: 3506ff69c3ec ("drm/radeon: use mmu_interval_notifier_insert") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > [ david: simplify description ] > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/mmu_notifier.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index 2e20f88e162d7..a7bae5de5fedc 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -947,7 +947,6 @@ static int __mmu_interval_notifier_insert( > struct mmu_notifier_subscriptions *subscriptions, unsigned long start, > unsigned long length, const struct mmu_interval_notifier_ops *ops) > { > - interval_sub->mm = mm; > interval_sub->ops = ops; > RB_CLEAR_NODE(&interval_sub->interval_tree.rb); > interval_sub->interval_tree.start = start; > @@ -964,8 +963,12 @@ static int __mmu_interval_notifier_insert( > if (WARN_ON(atomic_read(&mm->mm_users) <= 0)) > return -EINVAL; > > - /* pairs with mmdrop in mmu_interval_notifier_remove() */ > + /* > + * Pairs with mmdrop in mmu_interval_notifier_remove(). Drivers take a > + * non-NULL ->mm for "registered", so set it only with the reference. > + */ > mmgrab(mm); > + interval_sub->mm = mm; > > /* > * If some invalidate_range_start/end region is going on in parallel > > -- > 2.43.0 > -- Cheers, Lorenzo