From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932583AbbIVGYi (ORCPT ); Tue, 22 Sep 2015 02:24:38 -0400 Received: from mail-wi0-f173.google.com ([209.85.212.173]:38255 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755861AbbIVGYT (ORCPT ); Tue, 22 Sep 2015 02:24:19 -0400 From: Ingo Molnar To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Andy Lutomirski , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Waiman Long , Thomas Gleixner Subject: [PATCH 07/11] x86/mm: Remove pgd_list use from vmalloc_sync_all() Date: Tue, 22 Sep 2015 08:23:37 +0200 Message-Id: <1442903021-3893-8-git-send-email-mingo@kernel.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1442903021-3893-1-git-send-email-mingo@kernel.org> References: <1442903021-3893-1-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 | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index f890f5463ac1..9322d5ad3811 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -14,6 +14,7 @@ #include /* prefetchw */ #include /* exception_enter(), ... */ #include /* faulthandler_disabled() */ +#include /* find_lock_task_mm(), ... */ #include /* dotraplinkage, ... */ #include /* pgd_*(), ... */ @@ -237,24 +238,38 @@ void vmalloc_sync_all(void) for (address = VMALLOC_START & PMD_MASK; address >= TASK_SIZE && address < FIXADDR_TOP; address += PMD_SIZE) { - struct page *page; + struct task_struct *g; + + rcu_read_lock(); /* Task list walk */ spin_lock(&pgd_lock); - list_for_each_entry(page, &pgd_list, lru) { + + for_each_process(g) { + struct task_struct *p; + struct mm_struct *mm; spinlock_t *pgt_lock; - pmd_t *ret; + pmd_t *pmd_ret; + + p = find_lock_task_mm(g); + if (!p) + continue; - /* the pgt_lock only for Xen */ - pgt_lock = &pgd_page_get_mm(page)->page_table_lock; + mm = p->mm; + /* 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); + rcu_read_unlock(); } } -- 2.1.4