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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 1F76AC27C4F for ; Sat, 29 Jun 2024 21:29:42 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=VnqFJx5g; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WBQS33HFDz3cX5 for ; Sun, 30 Jun 2024 07:29:39 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=VnqFJx5g; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=145.40.73.55; helo=sin.source.kernel.org; envelope-from=helgaas@kernel.org; receiver=lists.ozlabs.org) Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WBQRG6gHpz30TK for ; Sun, 30 Jun 2024 07:28:58 +1000 (AEST) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id D148ECE10B9; Sat, 29 Jun 2024 21:28:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07CE9C2BBFC; Sat, 29 Jun 2024 21:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719696533; bh=HtXt70x632jQVkvZVa5+viDAiEo/vLpbpyG46HWBjMw=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=VnqFJx5ghuBk4Ih3CVJjWYCN0/ZeQE4bA9dgueRtqlOBnEj9bpHIblRRQS9pvQOq9 e1eHFjHr5+rNv2dGIMrkk3IAZlqwsKX7p+rD1r1vmjoqPl5r2aEZGCjwsQpiy3/x6B ysyxPdOQzeo0ZX9VEzv6T9NJsfU8dcWOxpkFNYAWzY/LBU0zuLZ2xf3++9jGcptCb1 Xp8Voz7uHR8O3pq3w/ncYUPGbyyGG5MBfyicJ+oqDiGO1BzaG9nKTI9pT87K9/QPad WGmS2gB4YANsUc/hqolrWiMuZCznLg98Ov/R1hZ8gbO540njo89EbUIDosTqYlZeua vy2FDJBTYP9+A== Date: Sat, 29 Jun 2024 16:28:51 -0500 From: Bjorn Helgaas To: Alistair Popple Subject: Re: [PATCH 02/13] pci/p2pdma: Don't initialise page refcount to one Message-ID: <20240629212851.GA1484889@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: linmiaohe@huawei.com, nvdimm@lists.linux.dev, jack@suse.cz, david@redhat.com, djwong@kernel.org, dave.hansen@linux.intel.com, david@fromorbit.com, peterx@redhat.com, linux-mm@kvack.org, will@kernel.org, hch@lst.de, dave.jiang@intel.com, vishal.l.verma@intel.com, linux-doc@vger.kernel.org, willy@infradead.org, jgg@ziepe.ca, catalin.marinas@arm.com, linux-ext4@vger.kernel.org, ira.weiny@intel.com, jhubbard@nvidia.com, npiggin@gmail.com, linux-cxl@vger.kernel.org, bhelgaas@google.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, tytso@mit.edu, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, logang@deltatee.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jun 27, 2024 at 10:54:17AM +1000, Alistair Popple wrote: > The reference counts for ZONE_DEVICE private pages should be > initialised by the driver when the page is actually allocated by the > driver allocator, not when they are first created. This is currently > the case for MEMORY_DEVICE_PRIVATE and MEMORY_DEVICE_COHERENT pages > but not MEMORY_DEVICE_PCI_P2PDMA pages so fix that up. If you tag the subject line with PCI, please run "git log --oneline drivers/pci/p2pdma.c" and make yours look like previous ones ("PCI/P2PDMA"). Also recast it to say something semantically useful about what it *does*, not what it *doesn't* do. Maybe something about initializing the refcount where the page is allocated? Especially since the only p2pdma.c change here is to "set_page_count(..., 1)", which looks like exactly the opposite of "don't initialize refcount to one". > Signed-off-by: Alistair Popple > --- > drivers/pci/p2pdma.c | 2 ++ > mm/memremap.c | 8 ++++---- > mm/mm_init.c | 4 +++- > 3 files changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 4f47a13..1e9ea32 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -128,6 +128,8 @@ static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj, > goto out; > } > > + set_page_count(virt_to_page(kaddr), 1); > + > /* > * vm_insert_page() can sleep, so a reference is taken to mapping > * such that rcu_read_unlock() can be done before inserting the > diff --git a/mm/memremap.c b/mm/memremap.c > index 40d4547..caccbd8 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -488,15 +488,15 @@ void free_zone_device_folio(struct folio *folio) > folio->mapping = NULL; > folio->page.pgmap->ops->page_free(folio_page(folio, 0)); > > - if (folio->page.pgmap->type != MEMORY_DEVICE_PRIVATE && > - folio->page.pgmap->type != MEMORY_DEVICE_COHERENT) > + if (folio->page.pgmap->type == MEMORY_DEVICE_PRIVATE || > + folio->page.pgmap->type == MEMORY_DEVICE_COHERENT) > + put_dev_pagemap(folio->page.pgmap); > + else if (folio->page.pgmap->type != MEMORY_DEVICE_PCI_P2PDMA) > /* > * Reset the refcount to 1 to prepare for handing out the page > * again. > */ > folio_set_count(folio, 1); > - else > - put_dev_pagemap(folio->page.pgmap); > } > > void zone_device_page_init(struct page *page) > diff --git a/mm/mm_init.c b/mm/mm_init.c > index 3ec0493..b7e1599 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -6,6 +6,7 @@ > * Author Mel Gorman > * > */ > +#include "linux/memremap.h" > #include > #include > #include > @@ -1014,7 +1015,8 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, > * which will set the page count to 1 when allocating the page. > */ > if (pgmap->type == MEMORY_DEVICE_PRIVATE || > - pgmap->type == MEMORY_DEVICE_COHERENT) > + pgmap->type == MEMORY_DEVICE_COHERENT || > + pgmap->type == MEMORY_DEVICE_PCI_P2PDMA) > set_page_count(page, 0); > } > > -- > git-series 0.9.1