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=1794329872; b=4TjdS7rZKxCfWzE+Nv381r2IEWZxNEf1fQH+uh3GGnQK3tzs5LOWX4UQBQZdcyxxZ4XN lRcdNwncN1827D7O6qg1q+hMOjq7PGfW3jYyyNfBufvezVOS3lfQNI5A1cs4ksY2cAkWD nYINUnFFHM4XhY2mYKZB5cSlniVyPFvXNtWbG6dDeigUKeaY4O0L4QJFBDbmRRd7qTf6u CF6/EPRV+1QsCGNHT/wPWyzyfCdbhSavzjT/K/KiFEk1DJ5LAtIK+cCg8ZF+GjIyA+EVk 91MsmgHy88Kyz69TIF5IEp3p1RXBqhNJe6YueXirmIAHgUJ5P/RAetg3UBTq4mdnbXw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794329872; h=Received:DKIM-Signature:From:Subject:Date:Message-Id:MIME-Version: Content-Type:Content-Transfer-Encoding:X-B4-Tracking:X-Change-ID:To: Cc:X-Mailer:X-Developer-Signature:X-Developer-Key; bh=yX9hjizhMmy5s5UE+lA9T2wHanfAnmcASyLGAaLx7sc=; b=m8HXZbYh/niShnPYBqj+3f9/KxVfVxUaBfa6xYlJb/UFZxgqsXIBIQU62s7JkBdR9j4+ 9RQVjhaA4mN6gH83IWLvxiQ0gBGhf84HzkwBLTiN8LuI6ulEtpogOZsaKTRlpI0vLxjlk belQk7EqFOGehoeljmlge2a3fabBd9zhjQ4TWgaYGMSruZc9XQlMP9UNqBMPuGuPyjd+5 bxVD/qqIYUy/KNGESZl2DHxw21Sn16f1XTkAruYNiym57T3xLAFMVcrKR65Qo2xdFq5mY kqdz0iwubr4z4JOgnpg8j4DVcopuH7TNGyhEi3hlOY18ErM0xsoT6bHhqPuvtJhO2sg== 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=ZVw6VuAb; 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 2289A606A325 for ; Tue, 10 Nov 2026 16:57:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ZVw6VuAb Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9FD91F0089F; Tue, 10 Nov 2026 16:57:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794329871; bh=yX9hjizhMmy5s5UE+lA9T2wHanfAnmcASyLGAaLx7sc=; h=From:Subject:Date:To:Cc; b=ZVw6VuAbWRO78atvQnc91ZRY4BJ+7QWDZCtCUZwD5jEVfpwEFaAffbw83L2cC1yGS VKSN1m6CUvoWVZ3eLjKlsbIJoqMPQ6hA3qxvPaOpRUeZCya9oOB2ASD0MtrohvW6eg d0vak2WgAM2ebTXLVS2Ite2zrZqGceW1wc6nvpTiEzA+shFb4sHoeR96Og7o66VSka wge3RV1uFUttG+sGo0w8Z1MWguZPhgq4JAZOAhHsjMyjUd5cUXbQKSrL/TokKmscE9 jNKyKk8y0aPo1Rne3FvNjaHTiHtFtqpcSHC54OUAsKCw3gTMl16CE+uQ+ntkDzs3Jg AxQgxChbkUsKQ== From: "Lorenzo Stoakes (ARM)" Subject: [PATCH 0/3] mm: only assert mmap and VMA locks if CONFIG_DEBUG_VM is set Date: Tue, 10 Nov 2026 16:57:42 +0000 Message-Id: <20261110-tame-vma-asserts-v1-0-be293ff499a7@kernel.org> 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 X-B4-Tracking: v=1; b=H4sIAAAAAAAC/x3MMQqAMAxA0atIZgNtkSJeRRyCppqhVRopgvTuF sc/vP+CchZWmLoXMhdROVML23ewHpR2RtlagzPOW2sN3hQZSyQkbfRWHEZDa/DE7Aw0dmUO8vz Lean1A7kYkSNiAAAA X-Change-ID: 20261110-tame-vma-asserts-480acf6aee20 To: Andrew Morton , Suren Baghdasaryan , "Liam R. Howlett" , Vlastimil Babka , Shakeel Butt Cc: ljs@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2282; i=ljs@kernel.org; h=from:subject:message-id; bh=l5iwL7Qd+mX6ZPWsXKwr0c6XQr5oPSXtaBAMqHbTYcA=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLI++/IclC+d4SBazfRe7PastMRCw0B1u/P9wdcOzPrEc rZlW2ttRykLgxgXg6yYIsvzL+L7g0TC5nVe8HeDmcPKBDKEgYtTACby6SPDf4fYQ39UapuEjI6a TmH6MKfq/CnRyokfmu6seix3wchwYjMjw1fV6ddD7SyWvt8r7t7xNGbKU/NYpXz/xVZPn3XfkHk TzAEA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Currently these asserts are all performed at runtime regardless of whether or not the kernel is intended for debugging mm code (i.e. whether or not CONFIG_DEBUG_VM is set). These are explicitly programmatic checks - that is, checking basic correctness in mm code which interacts with these locks. The problem with this is that checks like this are generally asserted in mm code using VM_WARN_ON_ONCE() and similar, and thus only checked if CONFIG_DEBUG_VM is set. So having some assertions which are unconditional and some not without it being clear, creates something of an unintended two-tier system. Since what is being asserted in these cases is exactly the same kind of condition as those asserted in VM_WARN_ON_ONCE() assertions, simply predicate them on CONFIG_DEBUG_VM. Retain assertions for mmap lock asserts if CONFIG_LOCKDEP is specified in order that expected lockdep assertions continue to function. The VMA lock implementation already performs lockdep tracking regardless of whether CONFIG_DEBUG_VM is set or not, so no changes are required there. --- Note that this series assumes [0] has landed and builds on it. That patch is the uncontroversial bit, this series contains the bits that are slightly more controversial (but not really :) [0]: https://lore.kernel.org/linux-mm/20261110-vma-fixup-debug-asserts-v1-1-0b2e0680cd7e@kernel.org/ To: Andrew Morton To: Suren Baghdasaryan To: Liam R. Howlett To: Vlastimil Babka To: Shakeel Butt Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Lorenzo Stoakes (ARM) --- Lorenzo Stoakes (ARM) (3): mm: only assert mmap locks if CONFIG_DEBUG_VM or lockdep is set mm: only assert VMA locks if CONFIG_DEBUG_VM is set mm: convert WARN_ON_ONCE()'s to VM_WARN_ON_ONCE() in VMA lock code include/linux/mmap_lock.h | 23 +++++++++++++++++++---- mm/mmap_lock.c | 6 +++--- 2 files changed, 22 insertions(+), 7 deletions(-) --- base-commit: b82f7651c53524960fe38a54aa69677dcddff655 change-id: 20261110-tame-vma-asserts-480acf6aee20 Cheers, -- Lorenzo Stoakes (ARM)