From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751373AbdK0I7S (ORCPT ); Mon, 27 Nov 2017 03:59:18 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:37517 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751138AbdK0I7R (ORCPT ); Mon, 27 Nov 2017 03:59:17 -0500 Date: Mon, 27 Nov 2017 09:59:06 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Dave Hansen , Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Borislav Petkov , Linus Torvalds Subject: [PATCH] x86/mm/kaiser: Use the other page_table_lock pattern Message-ID: <20171127085906.uth5hldrtbbqsnkr@hirez.programming.kicks-ass.net> References: <20171124091448.7649-1-mingo@kernel.org> <20171124091448.7649-26-mingo@kernel.org> <20171124133004.7cwe5r6hoesvod3i@hirez.programming.kicks-ass.net> <20171126151502.zrpwrdcx6yvrirb6@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171126151502.zrpwrdcx6yvrirb6@gmail.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Subject: x86/mm/kaiser: Use the other page_table_lock pattern From: Peter Zijlstra Date: Mon Nov 27 09:35:08 CET 2017 Use the other page_table_lock pattern; this removes the free from under the lock, reducing worst case hold times and makes it a leaf lock. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/mm/kaiser.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -183,11 +183,13 @@ static pte_t *kaiser_shadow_pagetable_wa return NULL; spin_lock(&shadow_table_allocation_lock); - if (p4d_none(*p4d)) + if (p4d_none(*p4d)) { set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page))); - else - free_page(new_pud_page); + new_pud_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pud_page) + free_page(new_pud_page); } pud = pud_offset(p4d, address); @@ -202,11 +204,13 @@ static pte_t *kaiser_shadow_pagetable_wa return NULL; spin_lock(&shadow_table_allocation_lock); - if (pud_none(*pud)) + if (pud_none(*pud)) { set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page))); - else - free_page(new_pmd_page); + new_pmd_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pmd_page) + free_page(new_pmd_page); } pmd = pmd_offset(pud, address); @@ -221,11 +225,13 @@ static pte_t *kaiser_shadow_pagetable_wa return NULL; spin_lock(&shadow_table_allocation_lock); - if (pmd_none(*pmd)) + if (pmd_none(*pmd)) { set_pmd(pmd, __pmd(_KERNPG_TABLE | __pa(new_pte_page))); - else - free_page(new_pte_page); + new_pte_page = 0; + } spin_unlock(&shadow_table_allocation_lock); + if (new_pte_page) + free_page(new_pte_page); } pte = pte_offset_kernel(pmd, address);