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[2003:cb:c70a:7e00:bb5b:b526:5b76:5824]) by smtp.gmail.com with ESMTPSA id h4-20020a5d6e04000000b0020d02262664sm5229194wrz.25.2022.06.17.10.33.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Jun 2022 10:33:13 -0700 (PDT) Message-ID: <7605beee-0a76-4ee9-e950-17419630f2cf@redhat.com> Date: Fri, 17 Jun 2022 19:33:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v5 01/13] mm: add zone device coherent type memory support Content-Language: en-US To: "Sierra Guiza, Alejandro (Alex)" , jgg@nvidia.com Cc: Felix.Kuehling@amd.com, linux-mm@kvack.org, rcampbell@nvidia.com, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, hch@lst.de, jglisse@redhat.com, apopple@nvidia.com, willy@infradead.org, akpm@linux-foundation.org References: <20220531200041.24904-1-alex.sierra@amd.com> <20220531200041.24904-2-alex.sierra@amd.com> <3ac89358-2ce0-7d0d-8b9c-8b0e5cc48945@redhat.com> <02ed2cb7-3ad3-8ffc-6032-04ae1853e234@amd.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <02ed2cb7-3ad3-8ffc-6032-04ae1853e234@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 17.06.22 19:20, Sierra Guiza, Alejandro (Alex) wrote: > > On 6/17/2022 4:40 AM, David Hildenbrand wrote: >> On 31.05.22 22:00, Alex Sierra wrote: >>> Device memory that is cache coherent from device and CPU point of view. >>> This is used on platforms that have an advanced system bus (like CAPI >>> or CXL). Any page of a process can be migrated to such memory. However, >>> no one should be allowed to pin such memory so that it can always be >>> evicted. >>> >>> Signed-off-by: Alex Sierra >>> Acked-by: Felix Kuehling >>> Reviewed-by: Alistair Popple >>> [hch: rebased ontop of the refcount changes, >>> removed is_dev_private_or_coherent_page] >>> Signed-off-by: Christoph Hellwig >>> --- >>> include/linux/memremap.h | 19 +++++++++++++++++++ >>> mm/memcontrol.c | 7 ++++--- >>> mm/memory-failure.c | 8 ++++++-- >>> mm/memremap.c | 10 ++++++++++ >>> mm/migrate_device.c | 16 +++++++--------- >>> mm/rmap.c | 5 +++-- >>> 6 files changed, 49 insertions(+), 16 deletions(-) >>> >>> diff --git a/include/linux/memremap.h b/include/linux/memremap.h >>> index 8af304f6b504..9f752ebed613 100644 >>> --- a/include/linux/memremap.h >>> +++ b/include/linux/memremap.h >>> @@ -41,6 +41,13 @@ struct vmem_altmap { >>> * A more complete discussion of unaddressable memory may be found in >>> * include/linux/hmm.h and Documentation/vm/hmm.rst. >>> * >>> + * MEMORY_DEVICE_COHERENT: >>> + * Device memory that is cache coherent from device and CPU point of view. This >>> + * is used on platforms that have an advanced system bus (like CAPI or CXL). A >>> + * driver can hotplug the device memory using ZONE_DEVICE and with that memory >>> + * type. Any page of a process can be migrated to such memory. However no one >> Any page might not be right, I'm pretty sure. ... just thinking about special pages >> like vdso, shared zeropage, ... pinned pages ... > Well, you cannot migrate long term pages, that's what I meant :) >> >>> + * should be allowed to pin such memory so that it can always be evicted. >>> + * >>> * MEMORY_DEVICE_FS_DAX: >>> * Host memory that has similar access semantics as System RAM i.e. DMA >>> * coherent and supports page pinning. In support of coordinating page >>> @@ -61,6 +68,7 @@ struct vmem_altmap { >>> enum memory_type { >>> /* 0 is reserved to catch uninitialized type fields */ >>> MEMORY_DEVICE_PRIVATE = 1, >>> + MEMORY_DEVICE_COHERENT, >>> MEMORY_DEVICE_FS_DAX, >>> MEMORY_DEVICE_GENERIC, >>> MEMORY_DEVICE_PCI_P2PDMA, >>> @@ -143,6 +151,17 @@ static inline bool folio_is_device_private(const struct folio *folio) >> In general, this LGTM, and it should be correct with PageAnonExclusive I think. >> >> >> However, where exactly is pinning forbidden? > > Long-term pinning is forbidden since it would interfere with the device > memory manager owning the > device-coherent pages (e.g. evictions in TTM). However, normal pinning > is allowed on this device type. I don't see updates to folio_is_pinnable() in this patch. So wouldn't try_grab_folio() simply pin these pages? What am I missing? -- Thanks, David / dhildenb 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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 69FE9CCA479 for ; Fri, 17 Jun 2022 17:33:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 79DF410E3A6; Fri, 17 Jun 2022 17:33:19 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 25E1810E45A for ; Fri, 17 Jun 2022 17:33:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655487197; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=l9t8ci2pOVMm92hWEf9qj7OSOv7zoUPsj9UgV8OEIRA=; b=MH90flJXY+UUDmSid2k1nD5RzwUrvHpR+L/7qp8uw1djLYcERSMIcQYFoBc8kDr5GkTKip W1hYYScAWpK9uGUhQ+NHxRUiApWINHs3SykRdbaxmRRbHjXFvL0Z0WrRm8A3z+XBJqiJmj N5Dd6v27kxXzzPdoPE/3gEnzHXOkDcw= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-381-7MrYfNqtNHKZ4G-UyhEB6w-1; Fri, 17 Jun 2022 13:33:16 -0400 X-MC-Unique: 7MrYfNqtNHKZ4G-UyhEB6w-1 Received: by mail-wm1-f69.google.com with SMTP id i188-20020a1c3bc5000000b0039db971c6d9so1696239wma.7 for ; Fri, 17 Jun 2022 10:33:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=l9t8ci2pOVMm92hWEf9qj7OSOv7zoUPsj9UgV8OEIRA=; b=Tijem8iVqDKr8oYJT3MfLVKFFAJq/gFSGp17XYEC5GKwH9YZBp31gViI7KrcL66qA6 if+uLawGRMqINnARKjVNz2XI37bhBz6YitLJWuRkSBy5cQd5siVmGEI5r6KNO2zt9k5G oHj4kOW3B9D3DIPGrDefN/CUdp4tXk9YV7XZCb1kGM4/oh6HRYLfQAHhNFaVluMr+erN Q6KsA1FWxOVD0FY+TkexjsKkvSFgF3Nw3UOvUsU94xbgT/bDaNF04NI32adp3umI2s0u 6KdxK6fMrbqrCNp3vtgwg0c4vT6EOTCYUdSt0ggqmOSvrswPOJkN6y28A2/SOEu1/GTl mGDw== X-Gm-Message-State: AJIora/v2svh3+tkLROXs6Qwn2ZlNIjX0dC5TmqBT9TrS5CRu9Hyot9d mD+OSj0Sb6xgracbEHOLIrvtUCkot07pDdA3OkyASCz9XKn4dYAYRgFpCrfohzW+mXlX56EXbpT qRagfL5p1q372BDU0Eu4eRW0KRcNs X-Received: by 2002:a5d:62ce:0:b0:21a:33d9:70eb with SMTP id o14-20020a5d62ce000000b0021a33d970ebmr8760934wrv.86.1655487194591; Fri, 17 Jun 2022 10:33:14 -0700 (PDT) X-Google-Smtp-Source: AGRyM1urFEzCzeOEUS5o/eRCkTO1px9MVS8RRmDRPHAiaj7roLYkwKxp344rt/xnUHDqok2Mu+dWjw== X-Received: by 2002:a5d:62ce:0:b0:21a:33d9:70eb with SMTP id o14-20020a5d62ce000000b0021a33d970ebmr8760916wrv.86.1655487194277; Fri, 17 Jun 2022 10:33:14 -0700 (PDT) Received: from ?IPV6:2003:cb:c70a:7e00:bb5b:b526:5b76:5824? 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[2003:cb:c70a:7e00:bb5b:b526:5b76:5824]) by smtp.gmail.com with ESMTPSA id h4-20020a5d6e04000000b0020d02262664sm5229194wrz.25.2022.06.17.10.33.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Jun 2022 10:33:13 -0700 (PDT) Message-ID: <7605beee-0a76-4ee9-e950-17419630f2cf@redhat.com> Date: Fri, 17 Jun 2022 19:33:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v5 01/13] mm: add zone device coherent type memory support To: "Sierra Guiza, Alejandro (Alex)" , jgg@nvidia.com References: <20220531200041.24904-1-alex.sierra@amd.com> <20220531200041.24904-2-alex.sierra@amd.com> <3ac89358-2ce0-7d0d-8b9c-8b0e5cc48945@redhat.com> <02ed2cb7-3ad3-8ffc-6032-04ae1853e234@amd.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <02ed2cb7-3ad3-8ffc-6032-04ae1853e234@amd.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rcampbell@nvidia.com, willy@infradead.org, Felix.Kuehling@amd.com, apopple@nvidia.com, amd-gfx@lists.freedesktop.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, jglisse@redhat.com, dri-devel@lists.freedesktop.org, akpm@linux-foundation.org, linux-ext4@vger.kernel.org, hch@lst.de Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 17.06.22 19:20, Sierra Guiza, Alejandro (Alex) wrote: > > On 6/17/2022 4:40 AM, David Hildenbrand wrote: >> On 31.05.22 22:00, Alex Sierra wrote: >>> Device memory that is cache coherent from device and CPU point of view. >>> This is used on platforms that have an advanced system bus (like CAPI >>> or CXL). Any page of a process can be migrated to such memory. However, >>> no one should be allowed to pin such memory so that it can always be >>> evicted. >>> >>> Signed-off-by: Alex Sierra >>> Acked-by: Felix Kuehling >>> Reviewed-by: Alistair Popple >>> [hch: rebased ontop of the refcount changes, >>> removed is_dev_private_or_coherent_page] >>> Signed-off-by: Christoph Hellwig >>> --- >>> include/linux/memremap.h | 19 +++++++++++++++++++ >>> mm/memcontrol.c | 7 ++++--- >>> mm/memory-failure.c | 8 ++++++-- >>> mm/memremap.c | 10 ++++++++++ >>> mm/migrate_device.c | 16 +++++++--------- >>> mm/rmap.c | 5 +++-- >>> 6 files changed, 49 insertions(+), 16 deletions(-) >>> >>> diff --git a/include/linux/memremap.h b/include/linux/memremap.h >>> index 8af304f6b504..9f752ebed613 100644 >>> --- a/include/linux/memremap.h >>> +++ b/include/linux/memremap.h >>> @@ -41,6 +41,13 @@ struct vmem_altmap { >>> * A more complete discussion of unaddressable memory may be found in >>> * include/linux/hmm.h and Documentation/vm/hmm.rst. >>> * >>> + * MEMORY_DEVICE_COHERENT: >>> + * Device memory that is cache coherent from device and CPU point of view. This >>> + * is used on platforms that have an advanced system bus (like CAPI or CXL). A >>> + * driver can hotplug the device memory using ZONE_DEVICE and with that memory >>> + * type. Any page of a process can be migrated to such memory. However no one >> Any page might not be right, I'm pretty sure. ... just thinking about special pages >> like vdso, shared zeropage, ... pinned pages ... > Well, you cannot migrate long term pages, that's what I meant :) >> >>> + * should be allowed to pin such memory so that it can always be evicted. >>> + * >>> * MEMORY_DEVICE_FS_DAX: >>> * Host memory that has similar access semantics as System RAM i.e. DMA >>> * coherent and supports page pinning. In support of coordinating page >>> @@ -61,6 +68,7 @@ struct vmem_altmap { >>> enum memory_type { >>> /* 0 is reserved to catch uninitialized type fields */ >>> MEMORY_DEVICE_PRIVATE = 1, >>> + MEMORY_DEVICE_COHERENT, >>> MEMORY_DEVICE_FS_DAX, >>> MEMORY_DEVICE_GENERIC, >>> MEMORY_DEVICE_PCI_P2PDMA, >>> @@ -143,6 +151,17 @@ static inline bool folio_is_device_private(const struct folio *folio) >> In general, this LGTM, and it should be correct with PageAnonExclusive I think. >> >> >> However, where exactly is pinning forbidden? > > Long-term pinning is forbidden since it would interfere with the device > memory manager owning the > device-coherent pages (e.g. evictions in TTM). However, normal pinning > is allowed on this device type. I don't see updates to folio_is_pinnable() in this patch. So wouldn't try_grab_folio() simply pin these pages? What am I missing? -- Thanks, David / dhildenb