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=1793057199; b=v5VHw7Kf97ECf36zfP/L8gUIcKEnabf3VKHk5qcVlFP734vEbv1a6CiQmWuETw4WbdUE FKuf847DpsZYtEsC/L2HR01hcTIMuptJgkIOo2eAgtOZlThOQrRnGc4OPxoJ2k0Db8Pyo B5i2mKUXJ/onASk+ojnXL4oltnUvtauKP+kHrxfgjXEuXhdM8jnvP308lHWM9AdpGn0W7 vRhTV+u30tL8b2NsCh+9SJVjCUSToiZs/r0rwwU/VoMd7MOp8gV5mLBqFs38PR1gAmWQD fjUbiCsodxqZUQCGj0YRnInZGrY9ZgX0e7VcNiOkq6g7li3j2fZLa0Aa189+CtlMwBg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793057199; 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=JD3h3UamRh59QcjyL8J1MuE/w/u1X5RZ3DOsE1wllXg=; b=NeQb2GcWBl5Inypx+1MhdXyhs1QJBavrKhzQAnVRw7fDgBWMtC61HFlGZRgWFOPyQZ4i leMfK5UUStfpZfCbWGFR/gWnhiBJwxiWRxMs8FtSosQ/U+r671WiC1aUlFox3lMYd8/D5 9776zCmnWSMg9zcikAfDdpMxMH1k20RvdJQ3beErtpMTpF+EKpFIZxHHw6NtcKLMstYmX Paf1qn3X3AtsxiTFqdu44V56FpUn3nstBCerh/DFpXUnVWwLYXbfChzbn8RIFhHxZR7Il DOAVElna8z1VlEwQTfTW+Aa4p/CJJiwg/qmYBdicuamtLdj7Ik0/Vr9aO7Ij6PUU0Yw== 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=NqxXcyZ5; 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 73544606A31A; Mon, 26 Oct 2026 23:26:39 +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=NqxXcyZ5 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06A8C1F01825; Mon, 26 Oct 2026 23:26:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793057199; bh=JD3h3UamRh59QcjyL8J1MuE/w/u1X5RZ3DOsE1wllXg=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=NqxXcyZ5B7hNxVICB8D7ZuTu2KTFj1aY/wZHjWEHcrphKUZXEhErMydzk2Pzo1mLO KXsakbOlKadHDvCpmoPg4VdpWYop82udMmVVbnJSsa/yNZfnIpnc7zXVJuFxKNqzsX XXtyntURfV0Gyys700YmRUpcZNsNBwSVXZSPdu5SAf1AyhwNb3x1lfgitOWD3HGdQS vWS7Cl3Pan8Rn7XnMFij0eGv/K6IbU4S0Jzeq3EhdCV3hZuhxaFbAcpEYOR+STaAHN NiDWgUxmVXVvm5yitg/azM9C5yVHptICOOnN2qnAup6cV1VLBTsoFalfWOvsoe9Zzc roonF+qboPgYw== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:48 +0100 Subject: [PATCH 28/46] 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: <20261027-fixes_core-v1-28-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-0-6f74bec9a5bb@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=1928; i=david@kernel.org; h=from:subject:message-id; bh=x0mKttz+HwDvoeWV/WYBCh6ori+6WykC26zRhsHss7s=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu358WvjBTPacmt4dPIdDk5tcpn+01cwTchGfUrDY2m /szsutzRykLgxgHg6yYIktQ8H2Dly/X1Va78THDzGFlAhnCwMUpABOZdZHhf0TH64MXTnQzGVbk qRb3zPUxmqEu+rl0VcOt4H8i+Tv3tjEyTI9WCD+789mjnlXPFlqk3zA4dezK72lrV9nE/lCeLr9 WlhcA 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 ] 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 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