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From: Christoph Hellwig <hch@infradead.org>
To: John Hubbard <jhubbard@nvidia.com>
Cc: 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>,
	Christoph Hellwig <hch@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 21:21:40 -0700	[thread overview]
Message-ID: <ZyG0VKUpFttPF30f@infradead.org> (raw)
In-Reply-To: <20241030030116.670307-1-jhubbard@nvidia.com>

On Tue, Oct 29, 2024 at 08:01:16PM -0700, John Hubbard wrote:
> A user-visible consequence has now appeared: user space can no longer
> pin more than 2GB of memory anymore on x86_64. That's because, on a 4KB
> PAGE_SIZE system, when user space tries to (indirectly, via a device
> driver that calls pin_user_pages()) pin 2GB, this requires an allocation
> of a folio pointers array of MAX_PAGE_ORDER size, which is the limit for
> kmalloc().

Do you have a report whee someone tries to pin that much memor in a
single call?  What driver is this?  Because it seems like a not very
smart thing to do.



  reply	other threads:[~2024-10-30  4:21 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 [this message]
2024-10-30  4:30   ` John Hubbard
2024-10-30  4:33     ` Christoph Hellwig
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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