From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793306438; b=zFrEy8jIMyfB11/rIxqHjPxgMnqVd3KDBHH9DmIlyUVk5r/JeVcLTxBN0V/m1RVA3YG4 PGdEGqrZ95aDea1GpWz4TVlSXbWldcZgFcyPyij2CWM+00QT9GONpvlZcyo8HSAwIGHfu QD+FaRP1Cszn3jfqbtM+Lwyx+h6vgmndPSjLpsO7b3czz5/F9WbBlQTYnR33SHBPMv4Cq IyvNuQEeVRdVzIu9/Trs8l1JxN7po3qt7Iln5KUvK1JgOMv13KyJk+zNbAka4x5gdFoE/ uA5ulSuwofHp9tJfwDgG1cBZc7xLAzRD6KDMqD30gdbsYGpeDTDX3xcfnWIKpptHqgg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793306438; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=QSDRgnr69YPTIztges5CfT2KnEGoLvf21RQ7Ru6EwMk=; b=zsQNgr/nDgxTBZ/bRndCZHcS42K3OXaOnMhoO5vjGnxobxn5MULUZR/2vgWRBJ7Gt6jP fYxwBfvnjBUSp09dG+o83Nv3GgQCUCJ19ldaIiWb2kHj551bla482pak3Xpj4bTjWOSOe JyoZpGHtRr0mmkf2JltxldmHamTk0MEEgDbqBthP+Swu5mBKwf9vFEjmwkzqpgJm/eR5U xdETh5E/bCJN/7Ky7BabNNEK1Om4BnPXukL0pgTxkr6iTRc5sDQ8tQr5rpGypXuP5tzhC /D0OJPRmQIlRy3jIp2puyDl9DqV28VNAP2FjjjsyUuPeEJEjw4zCvZbERuQL1n+fJZg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kSJM4jh0; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 686D4606A321; Thu, 29 Oct 2026 20:40:38 +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=kSJM4jh0 Received: by smtp.kernel.org (Postfix) with ESMTPSA id F16E01F01826; Thu, 29 Oct 2026 20:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306438; bh=QSDRgnr69YPTIztges5CfT2KnEGoLvf21RQ7Ru6EwMk=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=kSJM4jh0HrN4VoBlBOqhsPGwGw2Ay3L6UkwB26SEadkf6ghUVo2z8TB8QCJ9muHku 5O77SDUckn2sO3yoVq/4XT6gpdq26chxpQr5jmd+TFr7yyyjMEAT7vJlAlHNi2G586 9dRzcbSiqzIJZhkYCZd0MkRZjlSqG4A/IqkIfPVXCSD+uJYrJlLddKokdFu1Lpj4s+ AM4Rg32kxI2Hn7JiuuOIn7WunGYp4G6VoTkDjcU1gizGyXkzJyZ9GEOxzwegUo/KUo f8ea/Z5QTtcFqqdC8XZvDhfq5KUMWVmWRyPkk5jZK+YupM1MEDamRB8Ea2ZIKljyXO MS5d+tWdUKOVw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:24 +0100 Subject: [PATCH v2 29/47] mm/mmu_notifier: set ->mm only after mmgrab() X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-29-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , 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 Cc: 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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2087; i=david@kernel.org; h=from:subject:message-id; bh=c82hKzDD/9RIfU3f00HaLlK2GVigMUUm/EjoMU8UlA8=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer+3QEZsaWVS8/Mt/6UkCdn1zjjE9rGt3nrrZJ0dxZ 1tMXZtlRykLgxgHg6yYIktQ8H2Dly/X1Va78THDzGFlAhnCwMUpABOJ9WX4H/prQtCmW1M9M2oK 9NuZ999n01ZTbl/OzdHgtG6HjKPSZ0aGF04lWz43hK3uUjCvqbrEzXLhdlBiS+zbzR6tTzNsL7N zAgA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A 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 ] Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Reviewed-by: Lorenzo Stoakes (ARM) Signed-off-by: David Hildenbrand (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 2e20f88e162d..a7bae5de5fed 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