From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934833AbeBMJq1 (ORCPT ); Tue, 13 Feb 2018 04:46:27 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49468 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934268AbeBMJqW (ORCPT ); Tue, 13 Feb 2018 04:46:22 -0500 Date: Tue, 13 Feb 2018 11:46:11 +0200 From: Mike Rapoport To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Christopher Lameter , Guy Shattah , Anshuman Khandual , Michal Nazarewicz , Vlastimil Babka , David Nellans , Laura Abbott , Pavel Machek , Dave Hansen Subject: Re: [RFC PATCH 1/3] mm: make start_isolate_page_range() fail if already isolated References: <20180212222056.9735-1-mike.kravetz@oracle.com> <20180212222056.9735-2-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180212222056.9735-2-mike.kravetz@oracle.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 18021309-0008-0000-0000-000004CC3AA9 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18021309-0009-0000-0000-00001E5FFAF0 Message-Id: <20180213094610.GA2196@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-13_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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-1802130120 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 12, 2018 at 02:20:54PM -0800, Mike Kravetz wrote: > start_isolate_page_range() is used to set the migrate type of a > page block to MIGRATE_ISOLATE while attempting to start a > migration operation. It is assumed that only one thread is > attempting such an operation, and due to the limited number of > callers this is generally the case. However, there are no > guarantees and it is 'possible' for two threads to operate on > the same range. > > Since start_isolate_page_range() is called at the beginning of > such operations, have it return -EBUSY if MIGRATE_ISOLATE is > already set. > > This will allow start_isolate_page_range to serve as a > synchronization mechanism and will allow for more general use > of callers making use of these interfaces. > > Signed-off-by: Mike Kravetz > --- > mm/page_alloc.c | 8 ++++---- > mm/page_isolation.c | 10 +++++++++- > 2 files changed, 13 insertions(+), 5 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 76c9688b6a0a..064458f317bf 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7605,11 +7605,11 @@ static int __alloc_contig_migrate_range(struct compact_control *cc, > * @gfp_mask: GFP mask to use during compaction > * > * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES > - * aligned, however it's the caller's responsibility to guarantee that > - * we are the only thread that changes migrate type of pageblocks the > - * pages fall in. > + * aligned. The PFN range must belong to a single zone. > * > - * The PFN range must belong to a single zone. > + * The first thing this routine does is attempt to MIGRATE_ISOLATE all > + * pageblocks in the range. Once isolated, the pageblocks should not > + * be modified by others. > * > * Returns zero on success or negative error code. On success all > * pages which PFN is in [start, end) are allocated for the caller and > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 165ed8117bd1..e815879d525f 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -28,6 +28,13 @@ static int set_migratetype_isolate(struct page *page, int migratetype, > > spin_lock_irqsave(&zone->lock, flags); > > + /* > + * We assume we are the only ones trying to isolate this block. > + * If MIGRATE_ISOLATE already set, return -EBUSY > + */ > + if (is_migrate_isolate_page(page)) > + goto out; > + > pfn = page_to_pfn(page); > arg.start_pfn = pfn; > arg.nr_pages = pageblock_nr_pages; > @@ -166,7 +173,8 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) > * future will not be allocated again. > * > * start_pfn/end_pfn must be aligned to pageblock_order. > - * Returns 0 on success and -EBUSY if any part of range cannot be isolated. > + * Returns 0 on success and -EBUSY if any part of range cannot be isolated Nit: please s/Returns/Return:/ and keep the period in the end > + * or any part of the range is already set to MIGRATE_ISOLATE. > */ > int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, > unsigned migratetype, bool skip_hwpoisoned_pages) > -- > 2.13.6 > > -- > 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 > -- Sincerely yours, Mike. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 5E2916B0003 for ; Tue, 13 Feb 2018 04:46:25 -0500 (EST) Received: by mail-qk0-f199.google.com with SMTP id u194so15966663qka.20 for ; Tue, 13 Feb 2018 01:46:25 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. 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Violators will be prosecuted for from ; Tue, 13 Feb 2018 09:46:19 -0000 Date: Tue, 13 Feb 2018 11:46:11 +0200 From: Mike Rapoport Subject: Re: [RFC PATCH 1/3] mm: make start_isolate_page_range() fail if already isolated References: <20180212222056.9735-1-mike.kravetz@oracle.com> <20180212222056.9735-2-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180212222056.9735-2-mike.kravetz@oracle.com> Message-Id: <20180213094610.GA2196@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Christopher Lameter , Guy Shattah , Anshuman Khandual , Michal Nazarewicz , Vlastimil Babka , David Nellans , Laura Abbott , Pavel Machek , Dave Hansen On Mon, Feb 12, 2018 at 02:20:54PM -0800, Mike Kravetz wrote: > start_isolate_page_range() is used to set the migrate type of a > page block to MIGRATE_ISOLATE while attempting to start a > migration operation. It is assumed that only one thread is > attempting such an operation, and due to the limited number of > callers this is generally the case. However, there are no > guarantees and it is 'possible' for two threads to operate on > the same range. > > Since start_isolate_page_range() is called at the beginning of > such operations, have it return -EBUSY if MIGRATE_ISOLATE is > already set. > > This will allow start_isolate_page_range to serve as a > synchronization mechanism and will allow for more general use > of callers making use of these interfaces. > > Signed-off-by: Mike Kravetz > --- > mm/page_alloc.c | 8 ++++---- > mm/page_isolation.c | 10 +++++++++- > 2 files changed, 13 insertions(+), 5 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 76c9688b6a0a..064458f317bf 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7605,11 +7605,11 @@ static int __alloc_contig_migrate_range(struct compact_control *cc, > * @gfp_mask: GFP mask to use during compaction > * > * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES > - * aligned, however it's the caller's responsibility to guarantee that > - * we are the only thread that changes migrate type of pageblocks the > - * pages fall in. > + * aligned. The PFN range must belong to a single zone. > * > - * The PFN range must belong to a single zone. > + * The first thing this routine does is attempt to MIGRATE_ISOLATE all > + * pageblocks in the range. Once isolated, the pageblocks should not > + * be modified by others. > * > * Returns zero on success or negative error code. On success all > * pages which PFN is in [start, end) are allocated for the caller and > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 165ed8117bd1..e815879d525f 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -28,6 +28,13 @@ static int set_migratetype_isolate(struct page *page, int migratetype, > > spin_lock_irqsave(&zone->lock, flags); > > + /* > + * We assume we are the only ones trying to isolate this block. > + * If MIGRATE_ISOLATE already set, return -EBUSY > + */ > + if (is_migrate_isolate_page(page)) > + goto out; > + > pfn = page_to_pfn(page); > arg.start_pfn = pfn; > arg.nr_pages = pageblock_nr_pages; > @@ -166,7 +173,8 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages) > * future will not be allocated again. > * > * start_pfn/end_pfn must be aligned to pageblock_order. > - * Returns 0 on success and -EBUSY if any part of range cannot be isolated. > + * Returns 0 on success and -EBUSY if any part of range cannot be isolated Nit: please s/Returns/Return:/ and keep the period in the end > + * or any part of the range is already set to MIGRATE_ISOLATE. > */ > int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, > unsigned migratetype, bool skip_hwpoisoned_pages) > -- > 2.13.6 > > -- > 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 > -- Sincerely yours, Mike. -- 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