From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11C4D31714B for ; Sun, 14 Jun 2026 09:14:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781428484; cv=none; b=Fg3IJooa2H4sXc8+3r3j++d/Vx+XsTD7pk06jlOVp/iFkWAVFQO9oxcfOGQIHZofSFUJc0fN/ABXzrxDGGVChWdQssPNZdgyOnBdwR9sYfHcMjB5A02RBTqtgX4HVPLglOGz7E1CfcyxrpGisboOBtYEE7AH8TgCQ7ADdM8pLDc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781428484; c=relaxed/simple; bh=pMDQCbEdAremaxVE4eNOWM6qSqcfZc6GO4d6bu0Q+C4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=u0uvg3yT8FRcB3bz4kdqoSvgAPlDhIY/l5PW1a2DFOUc9ejPN8Li6oxQGdJVRXz0dAEiTLwbYEDjgmBsJPpCXpTf9GG/Gor3itfGSqP8l1trBPIo6ZxGtqgRjyHQ3nsrVxsQIgcQZwHgFBjY5FZ16QtEcMl1/hSRff1BDn6DJEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UMx8Eb/8; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UMx8Eb/8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9BD81F000E9; Sun, 14 Jun 2026 09:14:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781428482; bh=PTdII44FGFmJdbMtCPKaS2eB6vk6Xg9WicWBVorhrQU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=UMx8Eb/8JnZEGxjCkj5fbSZIF8ouy/FZaJqolliub6IojIr7yzYw9OXytXU+YyLzG 1sfXtl3YbiZTHx4pobKS44wrOe/9MYhm2tWwd31Ert3JNdVaXqg114iI+UWTuy4OjW eEq7hlRisAo9IafOG18VOinIoj/K4b0RqrIZFDM1y5lIoa8PmtHJeKDDrIZSW/aEVw WaSKWCYHK5mZ04tE5rKZ8HuRwYBK/0w2yG1YGIlxnc5hKe4rk9Nn3wgPZK3PHPflvl Us+XMr6qFdCT9iRh/a2jnmp39Sb0AR4c4PW9TiXmXDwBbHO7SOyAGNjWnkqwUDaRak h+seQ0Hl9eOnw== Date: Sun, 14 Jun 2026 12:14:35 +0300 From: Mike Rapoport To: Ethan Nelson-Moore Cc: Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-mm@kvack.org, linux-doc@vger.kernel.org, Andrew Morton , David Hildenbrand , Jonathan Corbet Subject: Re: [PATCH] docs/mm: describe current criteria for enabling split page table lock for PTE tables Message-ID: References: <20260613221448.98657-1-enelsonmoore@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260613221448.98657-1-enelsonmoore@gmail.com> On Sat, Jun 13, 2026 at 03:14:47PM -0700, Ethan Nelson-Moore wrote: > The mm documentation regarding split page table lock for PTE tables > refers to the CONFIG_SPLIT_PTLOCK_CPUS config option, which was > superseded by CONFIG_SPLIT_PTE_PTLOCKS in commit 394290cba966 ("mm: > turn USE_SPLIT_PTE_PTLOCKS / USE_SPLIT_PTE_PTLOCKS into Kconfig > options"). Update the documentation to refer to the current option and > document the situations in which this feature is not supported. > > Discovered while searching for CONFIG_* symbols referenced in the > kernel but not defined in any Kconfig file. > > Signed-off-by: Ethan Nelson-Moore > --- > Documentation/mm/split_page_table_lock.rst | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/Documentation/mm/split_page_table_lock.rst b/Documentation/mm/split_page_table_lock.rst > index cc3cd46abd1b..c9d16024543b 100644 > --- a/Documentation/mm/split_page_table_lock.rst > +++ b/Documentation/mm/split_page_table_lock.rst > @@ -37,9 +37,12 @@ There are helpers to lock/unlock a table and other accessor functions: > - pmd_lockptr() > returns pointer to PMD table lock; > > -Split page table lock for PTE tables is enabled compile-time if > -CONFIG_SPLIT_PTLOCK_CPUS (usually 4) is less or equal to NR_CPUS. > -If split lock is disabled, all tables are guarded by mm->page_table_lock. > +Split page table lock for PTE tables is enabled compile-time (via > +CONFIG_SPLIT_PTE_PTLOCKS) if NR_CPUS is greater than or equal to 4 and an > +MMU is being used. However, it is not supported on ARM processors with > +virtually indexed, physically tagged caches, PA-RISC processors older than > +the PA-8000, or 32-bit SPARC processors. If split lock is disabled, all "it is not supported on some architectures" would be enough IMO. > +tables are guarded by mm->page_table_lock. > > Split page table lock for PMD tables is enabled, if it's enabled for PTE > tables and the architecture supports it (see below). > -- > 2.43.0 > -- Sincerely yours, Mike.