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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Oleg Nesterov , Jason Gunthorpe , John Hubbard , Jan Kara , "Kirill A . Shutemov" , Pavel Begunkov , Mika Penttila , David Hildenbrand , Dave Chinner , Theodore Ts'o , Peter Xu , Matthew Rosato , "Paul E . McKenney" , Christian Borntraeger Subject: Re: [PATCH v9 0/3] mm/gup: disallow GUP writing to file-backed mappings by default Message-ID: References: <0eb31f6f-a122-4a5b-a959-03ed4dee1f3c@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0eb31f6f-a122-4a5b-a959-03ed4dee1f3c@lucifer.local> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: 04266140006 X-Rspam-User: X-Rspamd-Server: rspam06 X-Stat-Signature: tn9sckq61tporn6ogaqn57qnb1qsbnr8 X-HE-Tag: 1684127694-424078 X-HE-Meta: U2FsdGVkX1/ST2yPdsgz2i1bB+tbaap8q1eh3de+I3iLMCLWLMCafRlYipt5u6VJFjNliX92IENcnfEsZ6wBWvIwFQgs4Cf41tIpetEa//cbH2NrJS11hIlNA2BD/nAgIg02wfs/gDkRfohK6hKZiMZPXirHJ5CQccJbG1bxg96Iv2C+mOud+WliuPEGntueb40HPZpymsGC0hNec5ImgUtsbLJtVkDvpLKZQc6KpzEi4hcc4X7L1DajpwpksbUE0mU2lnaOPNtdJxWoQVHmao9lBM15FjSEjLYKuONUfhpXFxicKf6o3upkY6yk6F+DhaupkgyOrjEjToV6oz/PQacX3gRb9c4413NXsBWMrfY+aVM4t++Bfyt5unq9PPpri7YsM59c9GUEgUASW+bBfsW6JHLReKRWWXYyVuo3JTLs7BTCx8W/Z6/2e+EpydVNGeiUqVva4H5aB5XTmGDF2zMtQzjCJ3ubLK9RbYd+JdFkMNXFJ8AsZYZMrqzXIO1QIJsoC5yoc+2KTQtEXf+phRPbkJTC69x67WVjFI49rIZ7z8sWEZWXaM6xa06gFIpyuHRhuWwdkAXXT/rheZf3WNQGTZPYITtcP9Rwc4aOIQ4813f7IoiQ1iGgFjW5KvrVhr1Z18UEwc5m0uKBAmNxMTATOZrNcvImB5GSX5MYkwAuqcjRRmDEZtJSaIisACLUeZpd4XYc/mztiY8VfHTzXBR83j68XF+lEndBlLp+Y3shjGpxAKbmcIjYcuBp7IbiePr9SrkCxTLHEnGHO1xl3/o11iyaxkAEuKyUq1HRCiMZyUnaIIGjUS6YNvy9FCVBbumn4bSuAFTNxOMM6Y81iEW0Di/AvRNDRZh4a8ou4ISnVIr97N08AE8iQR/VeT3LI38BvWMzbc+bfA10USSV72L/vQ/JSrRd3JM7LJqvgjwvrS03JBrhhPaY5gMybls5RVjgI3m+DVmyQUP9c8d B1hbrSL1 52yeWK2g0eutiE5nUhPl2CHujL7M2ph5JosNqtYkHxVBU673EXSuNKWCxQ5PW5lRr0y69JBCB6Y+b6hIFHpinJtODjJBKZ06PFeNTkcWbl6TeWoWDesmaeVR6phs3SfnBYnxsjLwmXqiU24irpq30sdnVPpE/dpeq1kRtMs4p8vm1BRCttxx9lgT9rmIyse/eKBLr3oXf37jPf4JxXh+rBZn3Gs2yCRtZMqm0AjUoj39mxBlpIBYDsP6JSP21PX2pStCIVQ4prL8hCRL1z32sVrxwajZlNR49A7vtF2dqB3t5Bx8a1VDp4NS7Otb/A1sq+u4OgN1TI7N1HrZX2y3IC1QRsM09N3CbSIm6mgogNjYTOsRJFodZtoWwQqETeIE15Bww6lvSXjgRW8cHoSBEogcXmGs0ASVgfICHtMKImjC4eZAhlbWycDRmPRMlnhh2aoBq4bt3KDxjsBg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, May 14, 2023 at 08:20:04PM +0100, Lorenzo Stoakes wrote: > As discussed at LSF/MM, on the flight over I wrote a little repro [0] which > reliably triggers the ext4 warning by recreating the scenario described > above, using a small userland program and kernel module. > > This code is not perfect (plane code :) but does seem to do the job > adequately, also obviously this should only be run in a VM environment > where data loss is acceptable (in my case a small qemu instance). It would be really awesome if you could wire it up with and submit it to xfstests.