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Date: Tue, 19 Jun 2018 09:15:48 +0300
From: Leon Romanovsky <leon@kernel.org>
Subject: Re: [PATCH 2/2] mm: set PG_dma_pinned on get_user_pages*()
Message-ID: <20180619061548.GC7557@mtr-leonro.mtl.com>
References: <20180617012510.20139-1-jhubbard@nvidia.com>
 <20180617012510.20139-3-jhubbard@nvidia.com>
 <CAPcyv4i=eky-QrPcLUEqjsASuRUrFEWqf79hWe0mU8xtz6Jk-w@mail.gmail.com>
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To: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>, Jason Gunthorpe <jgg@ziepe.ca>, john.hubbard@gmail.com, Matthew Wilcox <willy@infradead.org>, Michal Hocko <mhocko@kernel.org>, Christopher Lameter <cl@linux.com>, Jan Kara <jack@suse.cz>, Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, linux-rdma <linux-rdma@vger.kernel.org>, John Hubbard <jhubbard@nvidia.com>


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On Mon, Jun 18, 2018 at 10:11:13AM +0200, Christoph Hellwig wrote:
> On Sun, Jun 17, 2018 at 01:10:04PM -0700, Dan Williams wrote:
> > I believe kernel behavior regression is a primary concern as now
> > fallocate() and truncate() can randomly fail where they didn't before.
>
> Fail or block forever due to actions of other unprivileged users.
>
> That is a complete no-go.

They will fail "properly" with some error, which is better than current
situation where those unprivileged users can trigger oops.

Thanks

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