From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A95FE374FA; Sat, 29 Jun 2024 21:28:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719696533; cv=none; b=ZmmPN+DDth5AUs+dVA3Zy1q67VoTFIY6mqLgXd4HHgCf9QwTljhM2adx2t7uPxdkhpYtnUWkdtHxKWWaFrOykx9JocDNXDjfMO6yC+iLsXuFghAbFrIPrwa36gjMkhFPB0PLk1d6FneoxAVHahetaID1BAG+DVaoUWzZv2MbOMI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719696533; c=relaxed/simple; bh=HtXt70x632jQVkvZVa5+viDAiEo/vLpbpyG46HWBjMw=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=moRBVwhoy0/uBa4JVJZd8I9XbLatM31IwIrc27PcHBuyN3hDwIKJRgCQOLAhonAiTxO+IGqEjh9svFvk5m+cm64fLp1Xs971OLHI74lRWhy8YNv3UwfdSqLx1dmTK5eCOH1hkxTUgvb/9cRo0KxeiOhfuAfqHip7Xn5Tss+jTHE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VnqFJx5g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VnqFJx5g" 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 Cc: dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, logang@deltatee.com, bhelgaas@google.com, jack@suse.cz, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, dave.hansen@linux.intel.com, ira.weiny@intel.com, willy@infradead.org, djwong@kernel.org, tytso@mit.edu, linmiaohe@huawei.com, david@redhat.com, peterx@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com Subject: Re: [PATCH 02/13] pci/p2pdma: Don't initialise page refcount to one Message-ID: <20240629212851.GA1484889@bhelgaas> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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