From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CA6EACD98D2 for ; Sun, 14 Jun 2026 09:14:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0FD586B0099; Sun, 14 Jun 2026 05:14:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0AE736B009B; Sun, 14 Jun 2026 05:14:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F06C46B009D; Sun, 14 Jun 2026 05:14:45 -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 E2E866B0099 for ; Sun, 14 Jun 2026 05:14:45 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 74F131C2C1C for ; Sun, 14 Jun 2026 09:14:45 +0000 (UTC) X-FDA: 84877958130.06.85B9583 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id DA850C0002 for ; Sun, 14 Jun 2026 09:14:43 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="UMx8Eb/8"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781428483; 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=PTdII44FGFmJdbMtCPKaS2eB6vk6Xg9WicWBVorhrQU=; b=xp+pwooHb1AQxlFat7qFXQSDR+3Mw2XW58GqD/soQHrARYYMR7oMk7gqCZjl+TJcK1iiSv jZhL3L07xkDjkVj+0IBFvgZV+qG9XTKdzGkVmUSt9XyxheELW6k5RRuj6GrrSiBM+q52sW YcnrwM8WUVy8H+SZxHEAVRwcMWAPC5o= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="UMx8Eb/8"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781428483; b=WWN8RreUiykVaJ0C4wNb+iTthlmGlwzkbDgW4sKLM+ehOYjxzIXbNsbgxsGJ3VAiA8ikoA /BHn7oaS4pCWQ9HfjVsskCci7pDi2wCIM0NGkxHDx9WrnDzBFLsFPiCuJeTTpzIMJQZq/X RzLIKDU8yODavh4tYUmTt1d3a7i6SkA= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C84FF44369; Sun, 14 Jun 2026 09:14:42 +0000 (UTC) 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260613221448.98657-1-enelsonmoore@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: DA850C0002 X-Stat-Signature: px5xt3qyo7nmk7ahx8rpgw7tusmeixb9 X-HE-Tag: 1781428483-331235 X-HE-Meta: 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 QsMCliX1 ePx8mzjoSJACesClDmfhzCT2c5HJWrOwKREqdi4SHS6cixDFO1OgBsrXknhGmnIeCwkUEdXw0Y3thCabaxWh1GlJWDOV4qsHyF3aHY8AD0MTxMiOeoJKa3Ngm4G4u6IFd+/bZHUTGHbbW+8Lsp9v52qTnuxxio0vKI/3PPqNxAcrrQS2Il4QTYdlIRB0x76eY1lxt5fX6tFy4AE14cXLElwvavMkP11ES/uURKEqeGjwsdSbpwZWQ1+53rLsG4bTQfQjB+HPIkjSSNNtSYyq6deADPw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.