From patchwork Tue May 26 17:33:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 1298276 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=sparclinux-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=default header.b=nSwIqx93; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49WgzX5pBzz9sSd for ; Wed, 27 May 2020 03:33:28 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730092AbgEZRdU (ORCPT ); Tue, 26 May 2020 13:33:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:50196 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729936AbgEZRdR (ORCPT ); Tue, 26 May 2020 13:33:17 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0E7752084C; Tue, 26 May 2020 17:33:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590514396; bh=lbK/NnvQIQSJaitrCSivAE5U2uxTHBSqQpwGc3le/pw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nSwIqx93A7dTWzoRvRfZxBng7tCYOkMubn2HuaULgKFiG67Kbu4MJ8XYUB5uVDPvP JgvBJIYnLl/A7h2w3brGL8dzlxJMTWrmHjQwkL80evOMw6HZyAy1Bcho9kWoY4dDok 5rFZ6FY3UkdrTB2zTClZ1Ird+/i4a1+h/AqDt7Kk= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: sparclinux@vger.kernel.org, Will Deacon , Peter Zijlstra , "David S . Miller" , Guenter Roeck , Mike Rapoport , kernel-team@android.com Subject: [PATCH 3/3] sparc32: mm: Only call ctor()/dtor() functions for first and last user Date: Tue, 26 May 2020 18:33:02 +0100 Message-Id: <20200526173302.377-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200526173302.377-1-will@kernel.org> References: <20200526173302.377-1-will@kernel.org> MIME-Version: 1.0 Sender: sparclinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: sparclinux@vger.kernel.org The SRMMU page-table allocator allocates multiple PTE tables per page, since they are only 1K in size. However, this means that calls to pgtable_pte_page_{ctor,dtor}() must be serialised and performed only by the first and last page-table allocation for the page respectively. Use the page reference count to track how many PTE tables we have allocated for a given page returned by the SRMMU allocator and only call the ctor()/dtor() functions for the first and last user respectively. Cc: David S. Miller Fixes: 8c8f3156dd40 ("sparc32: mm: Reduce allocation size for PMD and PTE tables") Signed-off-by: Will Deacon --- arch/sparc/mm/srmmu.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c index 589370a21b12..116d19a390f2 100644 --- a/arch/sparc/mm/srmmu.c +++ b/arch/sparc/mm/srmmu.c @@ -364,9 +364,13 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) if ((ptep = pte_alloc_one_kernel(mm)) == 0) return NULL; page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT); - if (!pgtable_pte_page_ctor(page)) { - return NULL; + spin_lock(&mm->page_table_lock); + if (page_ref_inc_return(page) == 2 && !pgtable_pte_page_ctor(page)) { + page_ref_dec(page); + ptep = NULL; } + spin_unlock(&mm->page_table_lock); + return ptep; } @@ -375,7 +379,11 @@ void pte_free(struct mm_struct *mm, pgtable_t ptep) struct page *page; page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT); - pgtable_pte_page_dtor(page); + spin_lock(&mm->page_table_lock); + if (page_ref_dec_return(page) == 1) + pgtable_pte_page_dtor(page); + spin_unlock(&mm->page_table_lock); + srmmu_free_nocache(ptep, SRMMU_PTE_TABLE_SIZE); }