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 46E2837D118 for ; Tue, 1 Sep 2026 11:18:17 +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=1788261499; cv=none; b=iNmlZ9K05GaDfLdRTsgIHDX5VcYhorxkpekhlF+K8Ed1VBgzkh/3A2/4wGyy4H1oaBVE4yLshByRx1c4gshwKSBIN9FhC8iUd1AJICR3TEBExvjGIJrdpOdkORwG/o6UnFiL/5up6Vx1JkaYJmzupsdKywZf4NMf4xlL0g4We6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788261499; c=relaxed/simple; bh=mjdsRXYGDi9rn9+moQt9xrIuTZ4f98XCgkv+wqfinSk=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=XKcW8Qy9RANQXGZSxz/09AR/XYCJogLLSInXoIOLDWa57WMLZkSRapkUiofpxStvDVrMEqu+YQbMpfPBsdLeRfDC26jikhC4xl3EOqOgWg87dYh7RqNu6xWNRoQia4pgEOpK63eDNu4yLAmAbMk5zwVL2QPxzo6xVgnn34FLZl0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eI2MB4Gs; 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="eI2MB4Gs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 592C11F000E9; Tue, 1 Sep 2026 11:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788261497; bh=mjdsRXYGDi9rn9+moQt9xrIuTZ4f98XCgkv+wqfinSk=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=eI2MB4Gshaz2z4wgyzbrVOYMia3lr6HsoP7LDiG6afkoWxjMlnwS9zctbkJJnVQ0z +4B7uQNeDN8yGIDlErpMBQoXKGuEBp6gn++s1A7F4pgFu3RVUwPZE0l7mS6YBG2Jrf YayKCsBjqEJ1M9KAV3dIw2fTJXa22/2U1ooqPm2xIgUHMY2BGD5L0YT6RYwF4eXV9n SAUssE5NzZQHQld50fgTXNMIDBaYFVshlaj9EaWuBv6s9c7RzhP1LCVjdb7B+582GG Z6+/H4OW3jrKmPVnpLj39CIRRJjsDADPzrA7TfDUpK8XpKKfj8CRS8SQ37NeG2UD3L dtEELNj0fCxRQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH 04/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU arm Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: "Vasily Gorbik" , linux-s390@vger.kernel.org, "Alexander Gordeev" , "Christian Borntraeger" , "Heiko Carstens" In-Reply-To: <20260901-rcu-pagetable-freeing-v1-4-5456a81c8212@kernel.org> References: <20260901-rcu-pagetable-freeing-v1-0-5456a81c8212@kernel.org> <20260901-rcu-pagetable-freeing-v1-4-5456a81c8212@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 01 Sep 2026 11:18:16 +0000 Message-Id: <20260901111817.592C11F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Commit a0ad5496b2b3 ("arm: mm: enable HAVE_RCU_TABLE_FREE logic") enabled > CONFIG_MMU_GATHER_RCU_TABLE_FREE (then named HAVE_RCU_TABLE_FREE) for SMP > arm architectures with LPAE enabled. >=20 > Regardless of whether CONFIG_ARM_LPAE is enabled or not, the same page > table freeing functions __pte_free_tlb() and __pmd_free_tlb() are used. >=20 > Non-LPAE PMD page tables are folded into the PGD and freed by > pgd_free() (PGD freeing is not part of mmu_gather page table freeing in a= ny > case), so this is a noop in this case. >=20 > Since commit 358d1c39c82a ("arm: convert various functions to use ptdescs= ") > both LPAE and non-LPAE PTE page table freeing uses tlb_remove_ptdesc(). >=20 > Thus all page table freeing is performed under RCU with > CONFIG_MMU_GATHER_RCU_TABLE_FREE enabled for LPAE and non-LPAE and thus it > need not be gated on LPAE. >=20 > A UP arm system can set CONFIG_PREEMPT_RCU, so a future pure RCU page > table walker requires MMU_GATHER_RCU_TABLE_FREE to be enabled on UP as > well, even if concurrent GUP fast is not possible there. >=20 > Therefore, it is both safe and desirable to set > CONFIG_MMU_GATHER_RCU_TABLE_FREE for all MMU arm architectures (nommu does > not perform mmu_gather operations). >=20 > This forms part of an overall effort to switch every architecture to this > mode. >=20 > Signed-off-by: Lorenzo Stoakes (ARM) Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260901-rcu-pageta= ble-freeing-v1-0-5456a81c8212@kernel.org?part=3D4