From patchwork Tue Nov 19 08:16:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11251483 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 60BBC138C for ; Tue, 19 Nov 2019 08:20:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 404D720878 for ; Tue, 19 Nov 2019 08:20:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="gp1SuuI6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727992AbfKSIUl (ORCPT ); Tue, 19 Nov 2019 03:20:41 -0500 Received: from hqemgate15.nvidia.com ([216.228.121.64]:19033 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727455AbfKSIQ6 (ORCPT ); Tue, 19 Nov 2019 03:16:58 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 19 Nov 2019 00:16:49 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Tue, 19 Nov 2019 00:16:52 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Tue, 19 Nov 2019 00:16:52 -0800 Received: from HQMAIL111.nvidia.com (172.20.187.18) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 19 Nov 2019 08:16:51 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 19 Nov 2019 08:16:50 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 19 Nov 2019 00:16:50 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?utf-8?b?QmrDtnJuIFQ=?= =?utf-8?b?w7ZwZWw=?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard , Christoph Hellwig Subject: [PATCH v6 04/24] mm: Cleanup __put_devmap_managed_page() vs ->page_free() Date: Tue, 19 Nov 2019 00:16:23 -0800 Message-ID: <20191119081643.1866232-5-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191119081643.1866232-1-jhubbard@nvidia.com> References: <20191119081643.1866232-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1574151409; bh=tsex47R2BQW/HRhxz4q5zTudp/GozzJHGnDF0/waCbA=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Type:Content-Transfer-Encoding; b=gp1SuuI66a3PONdY/pqKkgxYKXOfezgEqAEr9rPrdLuGxPmHb7ilMqLVoaeHD4LnO ZjOI1t5XS/C/Zd4vfaPb6e4PxFYZcPVGzhnQn6daxkNy8pE+LwcG0RlPBTgCeoFHjY /ca2D2ugd937CcZf0TjAt7BKiWNaalp3qxkabhpRsGos3lC2tsq0Tkvf7SIp1EQYDp acQVpOBMk7yUosdu0ZzEij5vpFX7qw07GT5VLUlILc+RirOJmf/vf+u9VVR+7Lt/zK gxgQVPpYam3E+UzFTN2K5dhowUXmTUQ8b5vbBXVAUxeABfLOr/FQLMlkjVrw9hnVGZ ie08E2O4oknlg== Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Dan Williams After the removal of the device-public infrastructure there are only 2 ->page_free() call backs in the kernel. One of those is a device-private callback in the nouveau driver, the other is a generic wakeup needed in the DAX case. In the hopes that all ->page_free() callbacks can be migrated to common core kernel functionality, move the device-private specific actions in __put_devmap_managed_page() under the is_device_private_page() conditional, including the ->page_free() callback. For the other page types just open-code the generic wakeup. Yes, the wakeup is only needed in the MEMORY_DEVICE_FSDAX case, but it does no harm in the MEMORY_DEVICE_DEVDAX and MEMORY_DEVICE_PCI_P2PDMA case. Cc: Jan Kara Cc: Christoph Hellwig Cc: Ira Weiny Reviewed-by: Christoph Hellwig Reviewed-by: Jérôme Glisse Signed-off-by: Dan Williams Signed-off-by: John Hubbard --- drivers/nvdimm/pmem.c | 6 ---- mm/memremap.c | 80 ++++++++++++++++++++++++------------------- 2 files changed, 44 insertions(+), 42 deletions(-) diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index f9f76f6ba07b..21db1ce8c0ae 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -338,13 +338,7 @@ static void pmem_release_disk(void *__pmem) put_disk(pmem->disk); } -static void pmem_pagemap_page_free(struct page *page) -{ - wake_up_var(&page->_refcount); -} - static const struct dev_pagemap_ops fsdax_pagemap_ops = { - .page_free = pmem_pagemap_page_free, .kill = pmem_pagemap_kill, .cleanup = pmem_pagemap_cleanup, }; diff --git a/mm/memremap.c b/mm/memremap.c index 03ccbdfeb697..e899fa876a62 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -27,7 +27,8 @@ static void devmap_managed_enable_put(void) static int devmap_managed_enable_get(struct dev_pagemap *pgmap) { - if (!pgmap->ops || !pgmap->ops->page_free) { + if (pgmap->type == MEMORY_DEVICE_PRIVATE && + (!pgmap->ops || !pgmap->ops->page_free)) { WARN(1, "Missing page_free method\n"); return -EINVAL; } @@ -414,44 +415,51 @@ void __put_devmap_managed_page(struct page *page) { int count = page_ref_dec_return(page); - /* - * If refcount is 1 then page is freed and refcount is stable as nobody - * holds a reference on the page. - */ - if (count == 1) { - /* Clear Active bit in case of parallel mark_page_accessed */ - __ClearPageActive(page); - __ClearPageWaiters(page); + /* still busy */ + if (count > 1) + return; - mem_cgroup_uncharge(page); + /* only triggered by the dev_pagemap shutdown path */ + if (count == 0) { + __put_page(page); + return; + } - /* - * When a device_private page is freed, the page->mapping field - * may still contain a (stale) mapping value. For example, the - * lower bits of page->mapping may still identify the page as - * an anonymous page. Ultimately, this entire field is just - * stale and wrong, and it will cause errors if not cleared. - * One example is: - * - * migrate_vma_pages() - * migrate_vma_insert_page() - * page_add_new_anon_rmap() - * __page_set_anon_rmap() - * ...checks page->mapping, via PageAnon(page) call, - * and incorrectly concludes that the page is an - * anonymous page. Therefore, it incorrectly, - * silently fails to set up the new anon rmap. - * - * For other types of ZONE_DEVICE pages, migration is either - * handled differently or not done at all, so there is no need - * to clear page->mapping. - */ - if (is_device_private_page(page)) - page->mapping = NULL; + /* notify page idle for dax */ + if (!is_device_private_page(page)) { + wake_up_var(&page->_refcount); + return; + } - page->pgmap->ops->page_free(page); - } else if (!count) - __put_page(page); + /* Clear Active bit in case of parallel mark_page_accessed */ + __ClearPageActive(page); + __ClearPageWaiters(page); + + mem_cgroup_uncharge(page); + + /* + * When a device_private page is freed, the page->mapping field + * may still contain a (stale) mapping value. For example, the + * lower bits of page->mapping may still identify the page as an + * anonymous page. Ultimately, this entire field is just stale + * and wrong, and it will cause errors if not cleared. One + * example is: + * + * migrate_vma_pages() + * migrate_vma_insert_page() + * page_add_new_anon_rmap() + * __page_set_anon_rmap() + * ...checks page->mapping, via PageAnon(page) call, + * and incorrectly concludes that the page is an + * anonymous page. Therefore, it incorrectly, + * silently fails to set up the new anon rmap. + * + * For other types of ZONE_DEVICE pages, migration is either + * handled differently or not done at all, so there is no need + * to clear page->mapping. + */ + page->mapping = NULL; + page->pgmap->ops->page_free(page); } EXPORT_SYMBOL(__put_devmap_managed_page); #endif /* CONFIG_DEV_PAGEMAP_OPS */