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[2003:cb:c702:dc00:2571:c3c2:c6ea:84ef]) by smtp.gmail.com with ESMTPSA id f19-20020a05600c155300b003c6f3e5ba42sm19113223wmg.46.2022.11.21.00.05.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Nov 2022 00:05:44 -0800 (PST) Message-ID: Date: Mon, 21 Nov 2022 09:05:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [PATCH v1] mm/gup: disallow FOLL_FORCE|FOLL_WRITE on hugetlb mappings Content-Language: en-US To: Mike Kravetz , Jason Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Peter Xu , John Hubbard , syzbot+f0b97304ef90f0d0b1dc@syzkaller.appspotmail.com References: <20221031152524.173644-1-david@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31.10.22 23:13, Mike Kravetz wrote: > On 10/31/22 13:14, Jason Gunthorpe wrote: >> On Mon, Oct 31, 2022 at 04:25:24PM +0100, David Hildenbrand wrote: >>> Cc: Andrew Morton >>> Cc: Mike Kravetz >>> Cc: Peter Xu >>> Cc: John Hubbard >>> Cc: Jason Gunthorpe >>> Reported-by: syzbot+f0b97304ef90f0d0b1dc@syzkaller.appspotmail.com >>> Signed-off-by: David Hildenbrand >>> --- >>> >>> I assume this has been broken at least since 2014, when mm/gup.c came to >>> life. I failed to come up with a suitable Fixes tag quickly. >> >> I'm worried this would break RDMA over hugetlbfs maps - which is a >> real thing people do. > > Yes, it is a real thing. Unfortunately, I do not know exactly how it is used. > >> >> MikeK do you have test cases? > > Sorry, I do not have any test cases. > > I can ask one of our product groups about their usage. But, that would > certainly not be a comprehensive view. With https://lkml.kernel.org/r/20221116102659.70287-1-david@redhat.com on it's way, the RDMA concern should be gone, hopefully. @Andrew, can you queue this one? Thanks. -- Thanks, David / dhildenb