From: Alistair Popple <apopple@nvidia.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-mm@kvack.org, david@fromorbit.com,
dan.j.williams@intel.com, jhubbard@nvidia.com,
rcampbell@nvidia.com, willy@infradead.org, jgg@nvidia.com,
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, 09 May 2024 16:14:32 -0700 [thread overview]
Message-ID: <878r0ivamq.fsf@nvdebian.thelocal> (raw)
In-Reply-To: <4393e0d9-28c5-4b85-b603-40e457c9beba@deltatee.com>
Logan Gunthorpe <logang@deltatee.com> writes:
> Hi Alistair,
>
> I was working on testing your patch set, however I'm dealing with some
> hardware issues at the moment so I haven't fully tested everything yet.
Oh great. I haven't extensively tested the p2pdma setup yet because I
rely on a pretty janky qemu setup to do so.
> I managed to find one issue though:
>
> On 2024-04-10 18:57, Alistair Popple wrote:
>> 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));
>> +
>
> kaddr may represent more than one page, so this will fail to map
> anything if the mapping size is greater than 4KB. There is a loop just
> below this that calls vm_insert_page(). Moving a set_page_count() call
> just before vm_insert_page() fixes the issue.
Good point. I'm in the middle of respinning this (I was hoping to get it
done before LSF/MM but I suspect my travel will preempt it) so will add
this fix.
Note that there are problems with both fs-dax and device-dax in this
version which the next one fixes, but any p2p dma testing would be
appreciated. Thanks!
> Thanks!
>
> Logan
next prev parent reply other threads:[~2024-05-09 23:17 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
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 [this message]
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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