From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753625AbeCUT2V (ORCPT ); Wed, 21 Mar 2018 15:28:21 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56438 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753470AbeCUTYr (ORCPT ); Wed, 21 Mar 2018 15:24:47 -0400 From: Mike Rapoport To: Jonathan Corbet Cc: Andrey Ryabinin , Richard Henderson , Ivan Kokshaysky , Matt Turner , Tony Luck , Fenghua Yu , Ralf Baechle , James Hogan , Michael Ellerman , Alexander Viro , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kasan-dev@googlegroups.com, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Mike Rapoport Subject: [PATCH 23/32] docs/vm: split_page_table_lock: convert to ReST format Date: Wed, 21 Mar 2018 21:22:39 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521660168-14372-1-git-send-email-rppt@linux.vnet.ibm.com> References: <1521660168-14372-1-git-send-email-rppt@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18032119-0040-0000-0000-00000425821B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18032119-0041-0000-0000-00002628877D Message-Id: <1521660168-14372-24-git-send-email-rppt@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-21_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803210221 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Mike Rapoport --- Documentation/vm/split_page_table_lock | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/Documentation/vm/split_page_table_lock b/Documentation/vm/split_page_table_lock index 62842a8..889b00b 100644 --- a/Documentation/vm/split_page_table_lock +++ b/Documentation/vm/split_page_table_lock @@ -1,3 +1,6 @@ +.. _split_page_table_lock: + +===================== Split page table lock ===================== @@ -11,6 +14,7 @@ access to the table. At the moment we use split lock for PTE and PMD tables. Access to higher level tables protected by mm->page_table_lock. There are helpers to lock/unlock a table and other accessor functions: + - pte_offset_map_lock() maps pte and takes PTE table lock, returns pointer to the taken lock; @@ -34,12 +38,13 @@ Split page table lock for PMD tables is enabled, if it's enabled for PTE tables and the architecture supports it (see below). Hugetlb and split page table lock ---------------------------------- +================================= Hugetlb can support several page sizes. We use split lock only for PMD level, but not for PUD. Hugetlb-specific helpers: + - huge_pte_lock() takes pmd split lock for PMD_SIZE page, mm->page_table_lock otherwise; @@ -47,7 +52,7 @@ Hugetlb-specific helpers: returns pointer to table lock; Support of split page table lock by an architecture ---------------------------------------------------- +=================================================== There's no need in special enabling of PTE split page table lock: everything required is done by pgtable_page_ctor() and pgtable_page_dtor(), @@ -73,7 +78,7 @@ NOTE: pgtable_page_ctor() and pgtable_pmd_page_ctor() can fail -- it must be handled properly. page->ptl ---------- +========= page->ptl is used to access split page table lock, where 'page' is struct page of page containing the table. It shares storage with page->private @@ -81,6 +86,7 @@ page of page containing the table. It shares storage with page->private To avoid increasing size of struct page and have best performance, we use a trick: + - if spinlock_t fits into long, we use page->ptr as spinlock, so we can avoid indirect access and save a cache line. - if size of spinlock_t is bigger then size of long, we use page->ptl as -- 2.7.4