From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932175AbbFMJwa (ORCPT ); Sat, 13 Jun 2015 05:52:30 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:33648 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751157AbbFMJtr (ORCPT ); Sat, 13 Jun 2015 05:49:47 -0400 From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andy Lutomirski , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Thomas Gleixner , Waiman Long Subject: [PATCH 08/12] x86/mm: Remove pgd_list use from vmalloc_sync_all() Date: Sat, 13 Jun 2015 11:49:11 +0200 Message-Id: <1434188955-31397-9-git-send-email-mingo@kernel.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1434188955-31397-1-git-send-email-mingo@kernel.org> References: <1434188955-31397-1-git-send-email-mingo@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The vmalloc() code uses vmalloc_sync_all() to synchronize changes to the global reference kernel PGD to task PGDs in certain rare cases, like register_die_notifier(). This use seems to be somewhat questionable, as most other vmalloc page table fixups are vmalloc_fault() driven, but nevertheless it's there and it's using the pgd_list. But we don't need the global list, as we can walk the task list under RCU. Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Waiman Long Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 50342825f221..366b8232f4b3 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -235,23 +235,35 @@ void vmalloc_sync_all(void) for (address = VMALLOC_START & PMD_MASK; address >= TASK_SIZE && address < FIXADDR_TOP; address += PMD_SIZE) { - struct page *page; - spin_lock(&pgd_lock); - list_for_each_entry(page, &pgd_list, lru) { + struct task_struct *g, *p; + + spin_lock(&pgd_lock); /* Implies rcu_read_lock(): */ + + for_each_process_thread(g, p) { + struct mm_struct *mm; spinlock_t *pgt_lock; - pmd_t *ret; + pmd_t *pmd_ret; - /* the pgt_lock only for Xen */ - pgt_lock = &pgd_page_get_mm(page)->page_table_lock; + task_lock(p); + mm = p->mm; + if (!mm) { + task_unlock(p); + continue; + } + /* The pgt_lock is only used on Xen: */ + pgt_lock = &mm->page_table_lock; spin_lock(pgt_lock); - ret = vmalloc_sync_one(page_address(page), address); + pmd_ret = vmalloc_sync_one(mm->pgd, address); spin_unlock(pgt_lock); - if (!ret) + task_unlock(p); + + if (!pmd_ret) break; } + spin_unlock(&pgd_lock); } } -- 2.1.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id 644D1280003 for ; Sat, 13 Jun 2015 05:49:47 -0400 (EDT) Received: by wgzl5 with SMTP id l5so12725742wgz.3 for ; Sat, 13 Jun 2015 02:49:47 -0700 (PDT) Received: from mail-wg0-x230.google.com (mail-wg0-x230.google.com. [2a00:1450:400c:c00::230]) by mx.google.com with ESMTPS id ec16si7855704wic.86.2015.06.13.02.49.45 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 13 Jun 2015 02:49:46 -0700 (PDT) Received: by wgzl5 with SMTP id l5so12725543wgz.3 for ; Sat, 13 Jun 2015 02:49:45 -0700 (PDT) From: Ingo Molnar Subject: [PATCH 08/12] x86/mm: Remove pgd_list use from vmalloc_sync_all() Date: Sat, 13 Jun 2015 11:49:11 +0200 Message-Id: <1434188955-31397-9-git-send-email-mingo@kernel.org> In-Reply-To: <1434188955-31397-1-git-send-email-mingo@kernel.org> References: <1434188955-31397-1-git-send-email-mingo@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andy Lutomirski , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Thomas Gleixner , Waiman Long The vmalloc() code uses vmalloc_sync_all() to synchronize changes to the global reference kernel PGD to task PGDs in certain rare cases, like register_die_notifier(). This use seems to be somewhat questionable, as most other vmalloc page table fixups are vmalloc_fault() driven, but nevertheless it's there and it's using the pgd_list. But we don't need the global list, as we can walk the task list under RCU. Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Waiman Long Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 50342825f221..366b8232f4b3 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -235,23 +235,35 @@ void vmalloc_sync_all(void) for (address = VMALLOC_START & PMD_MASK; address >= TASK_SIZE && address < FIXADDR_TOP; address += PMD_SIZE) { - struct page *page; - spin_lock(&pgd_lock); - list_for_each_entry(page, &pgd_list, lru) { + struct task_struct *g, *p; + + spin_lock(&pgd_lock); /* Implies rcu_read_lock(): */ + + for_each_process_thread(g, p) { + struct mm_struct *mm; spinlock_t *pgt_lock; - pmd_t *ret; + pmd_t *pmd_ret; - /* the pgt_lock only for Xen */ - pgt_lock = &pgd_page_get_mm(page)->page_table_lock; + task_lock(p); + mm = p->mm; + if (!mm) { + task_unlock(p); + continue; + } + /* The pgt_lock is only used on Xen: */ + pgt_lock = &mm->page_table_lock; spin_lock(pgt_lock); - ret = vmalloc_sync_one(page_address(page), address); + pmd_ret = vmalloc_sync_one(mm->pgd, address); spin_unlock(pgt_lock); - if (!ret) + task_unlock(p); + + if (!pmd_ret) break; } + spin_unlock(&pgd_lock); } } -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org