From: Gerd Hoffmann <kraxel@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: mhocko@suse.com, jmarchan@redhat.com,
Dongwon Kim <dongwon.kim@intel.com>,
David Hildenbrand <david@redhat.com>,
qemu-devel@nongnu.org, Junxiao Chang <junxiao.chang@intel.com>,
muchun.song@linux.dev,
Vivek Kasireddy <vivek.kasireddy@intel.com>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, James Houghton <jthoughton@google.com>,
stable@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH] udmabuf: revert 'Add support for mapping hugepages (v4)'
Date: Mon, 19 Jun 2023 14:35:15 +0200 [thread overview]
Message-ID: <jdfdmwanxzi6udltiezoqli77kutoeuzodet6tsfyyu4sibbom@yxhycebnts6j> (raw)
In-Reply-To: <20230608204927.88711-1-mike.kravetz@oracle.com>
On Thu, Jun 08, 2023 at 01:49:27PM -0700, Mike Kravetz wrote:
> This effectively reverts commit 16c243e99d33 ("udmabuf: Add support
> for mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG
> with page map counting as described here [1]. This issue pointed out
> that the udmabuf driver was making direct use of subpages of hugetlb
> pages. This is not a good idea, and no other mm code attempts such use.
> In addition to the mapcount issue, this also causes issues with hugetlb
> vmemmap optimization and page poisoning.
>
> For now, remove hugetlb support.
>
> If udmabuf wants to be used on hugetlb mappings, it should be changed to
> only use complete hugetlb pages. This will require different alignment
> and size requirements on the UDMABUF_CREATE API.
>
> [1] https://lore.kernel.org/linux-mm/20230512072036.1027784-1-junxiao.chang@intel.com/
>
> Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
prev parent reply other threads:[~2023-06-19 12:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 20:49 [PATCH] udmabuf: revert 'Add support for mapping hugepages (v4)' Mike Kravetz
2023-06-09 6:09 ` Greg Kroah-Hartman
2023-06-12 7:10 ` Kasireddy, Vivek
2023-06-12 7:46 ` David Hildenbrand
2023-06-13 8:26 ` Kasireddy, Vivek
2023-06-13 12:25 ` David Laight
2023-06-13 17:51 ` David Hildenbrand
2023-06-14 3:40 ` Hugh Dickins
2023-06-14 7:51 ` Kasireddy, Vivek
2023-06-15 9:48 ` David Hildenbrand
2023-06-19 12:35 ` Gerd Hoffmann [this message]
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