From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30868C48BE5 for ; Fri, 18 Jun 2021 03:02:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10977610A5 for ; Fri, 18 Jun 2021 03:02:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231852AbhFRDEI (ORCPT ); Thu, 17 Jun 2021 23:04:08 -0400 Received: from mga03.intel.com ([134.134.136.65]:25793 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231815AbhFRDEH (ORCPT ); Thu, 17 Jun 2021 23:04:07 -0400 IronPort-SDR: wde48Q8onOCWWWLuTHKh4oHb8HudVZw8WRmTCP3Oz5kFXFaK3W/IYnv/8PCSiQLY9pioGwoFmf c9IqvW1D4Y+A== X-IronPort-AV: E=McAfee;i="6200,9189,10018"; a="206524997" X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="206524997" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 IronPort-SDR: kDCIXbw7lwEjZFI+nFNOMy4qgHpPd6rsmqYlpb0ps01Z+DdBhWSAQ5G+mGTpSRcepgH2/cP20z fFfj3eWUWROQ== X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="451243562" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 Date: Thu, 17 Jun 2021 20:01:57 -0700 From: Ira Weiny To: Christoph Hellwig Cc: Jens Axboe , Thomas Gleixner , Thomas Bogendoerfer , Geoff Levand , Ilya Dryomov , Dongsheng Yang , Mike Snitzer , "James E.J. Bottomley" , dm-devel@redhat.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, ceph-devel@vger.kernel.org, linux-arch@vger.kernel.org, Herbert Xu , "David S. Miller" Subject: Re: [PATCH 01/18] mm: add a kunmap_local_dirty helper Message-ID: <20210618030157.GA1905674@iweiny-DESK2.sc.intel.com> References: <20210615132456.753241-1-hch@lst.de> <20210615132456.753241-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210615132456.753241-2-hch@lst.de> User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Jun 15, 2021 at 03:24:39PM +0200, Christoph Hellwig wrote: > Add a helper that calls flush_kernel_dcache_page before unmapping the > local mapping. flush_kernel_dcache_page is required for all pages > potentially mapped into userspace that were written to using kmap*, > so having a helper that does the right thing can be very convenient. > > Signed-off-by: Christoph Hellwig > --- > include/linux/highmem-internal.h | 7 +++++++ > include/linux/highmem.h | 4 ++++ > 2 files changed, 11 insertions(+) > > diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h > index 7902c7d8b55f..bd37706db147 100644 > --- a/include/linux/highmem-internal.h > +++ b/include/linux/highmem-internal.h > @@ -224,4 +224,11 @@ do { \ > __kunmap_local(__addr); \ > } while (0) > > +#define kunmap_local_dirty(__page, __addr) \ I think having to store the page and addr to return to kunmap_local_dirty() is going to be a pain in some code paths. Not a show stopper but see below... > +do { \ > + if (!PageSlab(__page)) \ Was there some clarification why the page can't be a Slab page? Or is this just an optimization? > + flush_kernel_dcache_page(__page); \ Is this required on 32bit systems? Why is kunmap_flush_on_unmap() not sufficient on 64bit systems? The normal kunmap_local() path does that. I'm sorry but I did not see a conclusion to my query on V1. Herbert implied the he just copied from the crypto code.[1] I'm concerned that this _dirty() call is just going to confuse the users of kmap even more. So why can't we get to the bottom of why flush_kernel_dcache_page() needs so much logic around it before complicating the general kernel users. I would like to see it go away if possible. Ira [1] https://lore.kernel.org/lkml/20210615050258.GA5208@gondor.apana.org.au/ > + kunmap_local(__addr); \ > +} while (0) > + > #endif > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 832b49b50c7b..65f548db4f2d 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -93,6 +93,10 @@ static inline void kmap_flush_unused(void); > * On HIGHMEM enabled systems mapping a highmem page has the side effect of > * disabling migration in order to keep the virtual address stable across > * preemption. No caller of kmap_local_page() can rely on this side effect. > + * > + * If data is written to the returned kernel mapping, the callers needs to > + * unmap the mapping using kunmap_local_dirty(), else kunmap_local() should > + * be used. > */ > static inline void *kmap_local_page(struct page *page); > > -- > 2.30.2 > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CED0C2B9F4 for ; Fri, 18 Jun 2021 03:02:32 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B94FC6135C for ; Fri, 18 Jun 2021 03:02:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B94FC6135C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G5kHV6yWVz3c5k for ; Fri, 18 Jun 2021 13:02:30 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=192.55.52.115; helo=mga14.intel.com; envelope-from=ira.weiny@intel.com; receiver=) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4G5kH66Nxyz2yyt for ; Fri, 18 Jun 2021 13:02:08 +1000 (AEST) IronPort-SDR: yJJL1GT7Fn2fiqU0GSvaDAm2RqGV9sWlZ7Vvt7KDjV14wETa2/bpaLF24jRnRUIvsRUTqGr7WT H242ltooh6Cw== X-IronPort-AV: E=McAfee;i="6200,9189,10018"; a="206305258" X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="206305258" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 IronPort-SDR: kDCIXbw7lwEjZFI+nFNOMy4qgHpPd6rsmqYlpb0ps01Z+DdBhWSAQ5G+mGTpSRcepgH2/cP20z fFfj3eWUWROQ== X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="451243562" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 Date: Thu, 17 Jun 2021 20:01:57 -0700 From: Ira Weiny To: Christoph Hellwig Subject: Re: [PATCH 01/18] mm: add a kunmap_local_dirty helper Message-ID: <20210618030157.GA1905674@iweiny-DESK2.sc.intel.com> References: <20210615132456.753241-1-hch@lst.de> <20210615132456.753241-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210615132456.753241-2-hch@lst.de> User-Agent: Mutt/1.11.1 (2018-12-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , linux-block@vger.kernel.org, Thomas Bogendoerfer , Herbert Xu , Mike Snitzer , "David S. Miller" , Geoff Levand , ceph-devel@vger.kernel.org, linux-mips@vger.kernel.org, Dongsheng Yang , linux-kernel@vger.kernel.org, "James E.J. Bottomley" , dm-devel@redhat.com, linux-arch@vger.kernel.org, Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Ilya Dryomov Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Jun 15, 2021 at 03:24:39PM +0200, Christoph Hellwig wrote: > Add a helper that calls flush_kernel_dcache_page before unmapping the > local mapping. flush_kernel_dcache_page is required for all pages > potentially mapped into userspace that were written to using kmap*, > so having a helper that does the right thing can be very convenient. > > Signed-off-by: Christoph Hellwig > --- > include/linux/highmem-internal.h | 7 +++++++ > include/linux/highmem.h | 4 ++++ > 2 files changed, 11 insertions(+) > > diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h > index 7902c7d8b55f..bd37706db147 100644 > --- a/include/linux/highmem-internal.h > +++ b/include/linux/highmem-internal.h > @@ -224,4 +224,11 @@ do { \ > __kunmap_local(__addr); \ > } while (0) > > +#define kunmap_local_dirty(__page, __addr) \ I think having to store the page and addr to return to kunmap_local_dirty() is going to be a pain in some code paths. Not a show stopper but see below... > +do { \ > + if (!PageSlab(__page)) \ Was there some clarification why the page can't be a Slab page? Or is this just an optimization? > + flush_kernel_dcache_page(__page); \ Is this required on 32bit systems? Why is kunmap_flush_on_unmap() not sufficient on 64bit systems? The normal kunmap_local() path does that. I'm sorry but I did not see a conclusion to my query on V1. Herbert implied the he just copied from the crypto code.[1] I'm concerned that this _dirty() call is just going to confuse the users of kmap even more. So why can't we get to the bottom of why flush_kernel_dcache_page() needs so much logic around it before complicating the general kernel users. I would like to see it go away if possible. Ira [1] https://lore.kernel.org/lkml/20210615050258.GA5208@gondor.apana.org.au/ > + kunmap_local(__addr); \ > +} while (0) > + > #endif > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 832b49b50c7b..65f548db4f2d 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -93,6 +93,10 @@ static inline void kmap_flush_unused(void); > * On HIGHMEM enabled systems mapping a highmem page has the side effect of > * disabling migration in order to keep the virtual address stable across > * preemption. No caller of kmap_local_page() can rely on this side effect. > + * > + * If data is written to the returned kernel mapping, the callers needs to > + * unmap the mapping using kunmap_local_dirty(), else kunmap_local() should > + * be used. > */ > static inline void *kmap_local_page(struct page *page); > > -- > 2.30.2 > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1D1AC48BE8 for ; Fri, 18 Jun 2021 07:13:23 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5C3E1613AA for ; 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Thu, 17 Jun 2021 23:02:00 -0400 X-MC-Unique: 2K2WIrwJMeueno106SIzUg-1 IronPort-SDR: mgYjTXnGchBhoMNFIV/uCiBmG/jzSZBWfw0FJ/lcKOUvfowHztOmob/a/07XeEkVyXdHUDVRHD BuLDyQ8SWeYw== X-IronPort-AV: E=McAfee;i="6200,9189,10018"; a="270334919" X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="270334919" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 IronPort-SDR: kDCIXbw7lwEjZFI+nFNOMy4qgHpPd6rsmqYlpb0ps01Z+DdBhWSAQ5G+mGTpSRcepgH2/cP20z fFfj3eWUWROQ== X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="451243562" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 20:01:58 -0700 Date: Thu, 17 Jun 2021 20:01:57 -0700 From: Ira Weiny To: Christoph Hellwig Message-ID: <20210618030157.GA1905674@iweiny-DESK2.sc.intel.com> References: <20210615132456.753241-1-hch@lst.de> <20210615132456.753241-2-hch@lst.de> MIME-Version: 1.0 In-Reply-To: <20210615132456.753241-2-hch@lst.de> User-Agent: Mutt/1.11.1 (2018-12-01) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Fri, 18 Jun 2021 03:13:11 -0400 Cc: Jens Axboe , linux-block@vger.kernel.org, Thomas Bogendoerfer , Herbert Xu , Mike Snitzer , "David S. Miller" , Geoff Levand , ceph-devel@vger.kernel.org, linux-mips@vger.kernel.org, Dongsheng Yang , linux-kernel@vger.kernel.org, "James E.J. Bottomley" , dm-devel@redhat.com, linux-arch@vger.kernel.org, Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Ilya Dryomov Subject: Re: [dm-devel] [PATCH 01/18] mm: add a kunmap_local_dirty helper X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Tue, Jun 15, 2021 at 03:24:39PM +0200, Christoph Hellwig wrote: > Add a helper that calls flush_kernel_dcache_page before unmapping the > local mapping. flush_kernel_dcache_page is required for all pages > potentially mapped into userspace that were written to using kmap*, > so having a helper that does the right thing can be very convenient. > > Signed-off-by: Christoph Hellwig > --- > include/linux/highmem-internal.h | 7 +++++++ > include/linux/highmem.h | 4 ++++ > 2 files changed, 11 insertions(+) > > diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h > index 7902c7d8b55f..bd37706db147 100644 > --- a/include/linux/highmem-internal.h > +++ b/include/linux/highmem-internal.h > @@ -224,4 +224,11 @@ do { \ > __kunmap_local(__addr); \ > } while (0) > > +#define kunmap_local_dirty(__page, __addr) \ I think having to store the page and addr to return to kunmap_local_dirty() is going to be a pain in some code paths. Not a show stopper but see below... > +do { \ > + if (!PageSlab(__page)) \ Was there some clarification why the page can't be a Slab page? Or is this just an optimization? > + flush_kernel_dcache_page(__page); \ Is this required on 32bit systems? Why is kunmap_flush_on_unmap() not sufficient on 64bit systems? The normal kunmap_local() path does that. I'm sorry but I did not see a conclusion to my query on V1. Herbert implied the he just copied from the crypto code.[1] I'm concerned that this _dirty() call is just going to confuse the users of kmap even more. So why can't we get to the bottom of why flush_kernel_dcache_page() needs so much logic around it before complicating the general kernel users. I would like to see it go away if possible. Ira [1] https://lore.kernel.org/lkml/20210615050258.GA5208@gondor.apana.org.au/ > + kunmap_local(__addr); \ > +} while (0) > + > #endif > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 832b49b50c7b..65f548db4f2d 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -93,6 +93,10 @@ static inline void kmap_flush_unused(void); > * On HIGHMEM enabled systems mapping a highmem page has the side effect of > * disabling migration in order to keep the virtual address stable across > * preemption. No caller of kmap_local_page() can rely on this side effect. > + * > + * If data is written to the returned kernel mapping, the callers needs to > + * unmap the mapping using kunmap_local_dirty(), else kunmap_local() should > + * be used. > */ > static inline void *kmap_local_page(struct page *page); > > -- > 2.30.2 > -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel