From: Christoph Hellwig <hch@infradead.org>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, linux-stable@vger.kernel.org,
Vivek Kasireddy <vivek.kasireddy@intel.com>,
David Hildenbrand <david@redhat.com>,
Dave Airlie <airlied@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Jason Gunthorpe <jgg@nvidia.com>, Peter Xu <peterx@redhat.com>,
Arnd Bergmann <arnd@arndb.de>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Dongwon Kim <dongwon.kim@intel.com>,
Hugh Dickins <hughd@google.com>,
Junxiao Chang <junxiao.chang@intel.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH] mm/gup: restore the ability to pin more than 2GB at a time
Date: Tue, 29 Oct 2024 21:33:28 -0700 [thread overview]
Message-ID: <ZyG3GAvTHpRL9tnU@infradead.org> (raw)
In-Reply-To: <249d2614-0bcc-4ca8-b24e-7c0578a81dce@nvidia.com>
On Tue, Oct 29, 2024 at 09:30:41PM -0700, John Hubbard wrote:
> I do, yes. And what happens is that when you use GPUs, drivers like
> to pin system memory, and then point the GPU page tables to that
> memory. For older GPUs that don't support replayable page faults,
> that's required.
>
> So this behavior has been around forever.
>
> The customer was qualifying their software and noticed that before
> Linux 6.10, they could allocate >2GB, and with 6.11, they could
> not.
>
> Whether it is "wise" for user space to allocate that much at once
> is a reasonable question, but at least one place is (or was!) doing
> it.
Still missing a callchain, which make me suspect that it is your weird
out of tree driver, in which case this simply does not matter.
next prev parent reply other threads:[~2024-10-30 4:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-30 3:01 John Hubbard
2024-10-30 4:21 ` Christoph Hellwig
2024-10-30 4:30 ` John Hubbard
2024-10-30 4:33 ` Christoph Hellwig [this message]
2024-10-30 4:39 ` John Hubbard
2024-10-30 4:42 ` Christoph Hellwig
2024-10-30 4:44 ` John Hubbard
2024-10-30 6:18 ` Alistair Popple
2024-10-30 6:50 ` John Hubbard
2024-10-30 8:34 ` David Hildenbrand
2024-10-30 9:01 ` David Hildenbrand
2024-10-30 18:34 ` John Hubbard
2024-10-31 0:02 ` Jason Gunthorpe
2024-10-31 0:17 ` John Hubbard
2024-10-31 0:25 ` Jason Gunthorpe
2024-10-31 0:47 ` John Hubbard
2024-10-30 12:04 ` Jason Gunthorpe
2024-10-30 17:25 ` John Hubbard
2024-10-30 11:59 ` Jason Gunthorpe
2024-10-30 11:03 ` Vlastimil Babka
2024-10-30 17:29 ` John Hubbard
2024-10-30 17:42 ` Vlastimil Babka
2024-10-30 17:49 ` John Hubbard
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