From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: linux-mm@kvack.org, david@fromorbit.com,
dan.j.williams@intel.com, jhubbard@nvidia.com,
rcampbell@nvidia.com, willy@infradead.org,
linux-fsdevel@vger.kernel.org, jack@suse.cz, djwong@kernel.org,
hch@lst.de, david@redhat.com, ruansy.fnst@fujitsu.com,
nvdimm@lists.linux.dev, linux-xfs@vger.kernel.org,
linux-ext4@vger.kernel.org, jglisse@redhat.com
Subject: Re: [RFC 03/10] pci/p2pdma: Don't initialise page refcount to one
Date: Thu, 11 Apr 2024 09:29:27 -0300 [thread overview]
Message-ID: <20240411122927.GR5383@nvidia.com> (raw)
In-Reply-To: <a443974e64917824e078485d4e755ef04c89d73f.1712796818.git-series.apopple@nvidia.com>
On Thu, Apr 11, 2024 at 10:57:24AM +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.
>
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
> 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 fa7370f..ab7ef18 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;
> }
>
> + get_page(virt_to_page(kaddr));
> +
Should this be
set_page_count(page, 1)
If the refcount is already known to be 0 ?
> @@ -508,15 +508,15 @@ void free_zone_device_page(struct page *page)
> page->mapping = NULL;
> page->pgmap->ops->page_free(page);
>
> - if (page->pgmap->type != MEMORY_DEVICE_PRIVATE &&
> - page->pgmap->type != MEMORY_DEVICE_COHERENT)
> + if (page->pgmap->type == MEMORY_DEVICE_PRIVATE ||
> + page->pgmap->type == MEMORY_DEVICE_COHERENT)
> + put_dev_pagemap(page->pgmap);
Not related, but we should really be getting rid of this devmap
refcount traffic too, IMHO..
If an implementation wants this then it should hook the page
free/alloc callbacks and do this, not put it in the core code.
Jason
next prev parent reply other threads:[~2024-04-11 12:29 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 0:57 [RFC 00/10] fs/dax: Fix FS DAX page reference counts Alistair Popple
2024-04-11 0:57 ` [RFC 01/10] mm/gup.c: Remove redundant check for PCI P2PDMA page Alistair Popple
2024-04-11 12:59 ` Jason Gunthorpe
2024-04-11 13:47 ` David Hildenbrand
2024-04-12 1:37 ` Alistair Popple
2024-04-11 0:57 ` [RFC 02/10] mm/hmm: Remove dead check for HugeTLB and FS DAX Alistair Popple
2024-04-11 12:25 ` Jason Gunthorpe
2024-04-11 13:37 ` Peter Xu
2024-04-12 1:28 ` Alistair Popple
2024-04-11 0:57 ` [RFC 03/10] pci/p2pdma: Don't initialise page refcount to one Alistair Popple
2024-04-11 12:29 ` Jason Gunthorpe [this message]
2024-04-12 5:40 ` Alistair Popple
2024-04-12 17:20 ` Dan Williams
2024-05-09 21:59 ` Logan Gunthorpe
2024-05-09 23:14 ` Alistair Popple
2024-04-11 0:57 ` [RFC 04/10] fs/dax: Don't track page mapping/index Alistair Popple
2024-04-12 15:22 ` Jan Kara
2024-04-12 17:31 ` Dan Williams
2024-04-15 7:03 ` Alistair Popple
2024-04-15 20:51 ` Dan Williams
2024-04-16 0:07 ` Alistair Popple
2024-04-16 0:36 ` Dan Williams
2024-04-12 17:21 ` Dan Williams
2024-04-11 0:57 ` [RFC 05/10] fs/dax: Refactor wait for dax idle page Alistair Popple
2024-04-12 14:37 ` Jan Kara
2024-04-13 20:19 ` John Hubbard
2024-04-15 8:41 ` Alistair Popple
2024-04-11 0:57 ` [RFC 06/10] fs/dax: Add dax_page_free callback Alistair Popple
2024-04-11 0:57 ` [RFC 07/10] mm: Allow compound zone device pages Alistair Popple
2024-04-11 12:32 ` Jason Gunthorpe
2024-04-11 14:10 ` Matthew Wilcox
2024-04-12 1:38 ` Alistair Popple
2024-04-11 0:57 ` [RFC 08/10] fs/dax: Properly refcount fs dax pages Alistair Popple
2024-04-11 0:57 ` [RFC 09/10] mm/khugepage.c: Warn if trying to scan devmap pmd Alistair Popple
2024-04-11 13:45 ` David Hildenbrand
2024-04-12 1:34 ` Alistair Popple
2024-04-11 0:57 ` [RFC 10/10] mm: Remove pXX_devmap Alistair Popple
2024-04-11 12:57 ` Jason Gunthorpe
2024-04-11 17:28 ` [RFC 00/10] fs/dax: Fix FS DAX page reference counts Dan Williams
2024-04-11 17:35 ` Jason Gunthorpe
2024-04-11 17:56 ` Dan Williams
2024-04-12 3:54 ` Alistair Popple
2024-04-12 6:55 ` Alistair Popple
2024-04-12 11:53 ` Jason Gunthorpe
2024-04-12 17:32 ` Dan Williams
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