From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751906Ab1HSHs4 (ORCPT ); Fri, 19 Aug 2011 03:48:56 -0400 Received: from smtp-out.google.com ([216.239.44.51]:45654 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750746Ab1HSHsy (ORCPT ); Fri, 19 Aug 2011 03:48:54 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=dkim-signature:from:to:cc:subject:date:message-id:x-mailer: in-reply-to:references:x-system-of-record; b=CRiQQZBME84WYfKVC2rYv7SASRlKeS12kdfZzN4yeEKzEAUHRJl+RHpqbGPr8XDon A0/CnQHfYAzNHavgimB4A== From: Michel Lespinasse To: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrea Arcangeli , Hugh Dickins , Minchan Kim , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Shaohua Li Subject: [PATCH 1/9] mm: rcu read lock for getting reference on pages in migration_entry_wait() Date: Fri, 19 Aug 2011 00:48:23 -0700 Message-Id: <1313740111-27446-2-git-send-email-walken@google.com> X-Mailer: git-send-email 1.7.3.1 In-Reply-To: <1313740111-27446-1-git-send-email-walken@google.com> References: <1313740111-27446-1-git-send-email-walken@google.com> X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org migration_entry_wait() needs to take the rcu read lock so that page counts can be guaranteed to be stable after one rcu grace period. Signed-off-by: Michel Lespinasse --- mm/migrate.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 666e4e6..6f3b5db 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -193,6 +193,7 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, struct page *page; ptep = pte_offset_map_lock(mm, pmd, address, &ptl); + rcu_read_lock(); pte = *ptep; if (!is_swap_pte(pte)) goto out; @@ -212,11 +213,13 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, */ if (!get_page_unless_zero(page)) goto out; + rcu_read_unlock(); pte_unmap_unlock(ptep, ptl); wait_on_page_locked(page); put_page(page); return; out: + rcu_read_unlock(); pte_unmap_unlock(ptep, ptl); } -- 1.7.3.1