Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753562AbcKRRV2 (ORCPT ); Fri, 18 Nov 2016 12:21:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42384 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932290AbcKRRRq (ORCPT ); Fri, 18 Nov 2016 12:17:46 -0500 From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= To: akpm@linux-foundation.org, , linux-mm@kvack.org Cc: John Hubbard , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Dan Williams , Ross Zwisler Subject: [HMM v13 04/18] mm/ZONE_DEVICE/free-page: callback when page is freed Date: Fri, 18 Nov 2016 13:18:13 -0500 Message-Id: <1479493107-982-5-git-send-email-jglisse@redhat.com> In-Reply-To: <1479493107-982-1-git-send-email-jglisse@redhat.com> References: <1479493107-982-1-git-send-email-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Fri, 18 Nov 2016 17:17:46 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2306 Lines: 67 When a ZONE_DEVICE page refcount reach 1 it means it is free and nobody is holding a reference on it (only device to which the memory belong do). Add a callback and call it when that happen so device driver can implement their own free page management. Signed-off-by: Jérôme Glisse Cc: Dan Williams Cc: Ross Zwisler --- include/linux/memremap.h | 4 ++++ kernel/memremap.c | 8 ++++++++ 2 files changed, 12 insertions(+) diff --git a/include/linux/memremap.h b/include/linux/memremap.h index fe61dca..469c88d 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -37,17 +37,21 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start) /** * struct dev_pagemap - metadata for ZONE_DEVICE mappings + * @free_devpage: free page callback when page refcount reach 1 * @altmap: pre-allocated/reserved memory for vmemmap allocations * @res: physical address range covered by @ref * @ref: reference count that pins the devm_memremap_pages() mapping * @dev: host device of the mapping for debug + * @data: privata data pointer for free_devpage * @flags: memory flags (look for MEMORY_FLAGS_NONE in memory_hotplug.h) */ struct dev_pagemap { + void (*free_devpage)(struct page *page, void *data); struct vmem_altmap *altmap; const struct resource *res; struct percpu_ref *ref; struct device *dev; + void *data; int flags; }; diff --git a/kernel/memremap.c b/kernel/memremap.c index 438a73aa2..3d28048 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -190,6 +190,12 @@ EXPORT_SYMBOL(get_zone_device_page); void put_zone_device_page(struct page *page) { + /* + * If refcount is 1 then page is freed and refcount is stable as nobody + * holds a reference on the page. + */ + if (page->pgmap->free_devpage && page_count(page) == 1) + page->pgmap->free_devpage(page, page->pgmap->data); put_dev_pagemap(page->pgmap); } EXPORT_SYMBOL(put_zone_device_page); @@ -326,6 +332,8 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, pgmap->ref = ref; pgmap->res = &page_map->res; pgmap->flags = flags | MEMORY_DEVICE; + pgmap->free_devpage = NULL; + pgmap->data = NULL; mutex_lock(&pgmap_lock); error = 0; -- 2.4.3