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b=XQ+qVZlJVKORfcipef1lFWfojAwgH+j7aVfm+jtfayHGyNZxlkDkiR/BVavfChigE OubmG23nxZaVDGz/3t3nCu13VAtZSvs3W3ptAqfD1i/2cYdNjkwWyhWhKH7BaNnpvy yihmut6lU0YBkhwgWI6ns3ffkMSrvgk4GbP4w+xk= Date: Thu, 10 Apr 2025 20:43:38 -0700 From: Andrew Morton To: Baoquan He Cc: linux-mm@kvack.org, david@redhat.com, osalvador@suse.de, yanjun.zhu@linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Message-Id: <20250410204338.4b2101afdf18d8898390ef58@linux-foundation.org> In-Reply-To: <20250410035717.473207-2-bhe@redhat.com> References: <20250410035717.473207-1-bhe@redhat.com> <20250410035717.473207-2-bhe@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: w9aa9wxs5m319efimw3y5wmbit17uju7 X-Rspam-User: X-Rspamd-Queue-Id: D034A20002 X-HE-Tag: 1744343020-585280 X-HE-Meta: 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 wL8W34IC pr+qPubtSRbALDF8xBH1F6+Enq2NGY6k1MULXfOY4Fc1DTNFwWi+yn7YVQFxKXvXjN2xqqe8u5Azzfc0aqm+yAaHnUMxcUHoVbUCoaOAp5wgSGLfi1MGN6lin7SfTHCKjx1dqECMJL6Dt/9DzHeRAoTlEswCjbQfsrpkADaXtGQKTlBxj976DIj22xLACm/fxm15p+Di5A3ctXn3f10QuWeBNr5KRl/riysuVQww4/XSAsyvqoumTUAyh+EGIm2qqT9gXEziHHI7Mg/XoqDED8df9PtaJmg6kNlU+kIGqc8bU0JGtL7Dh5Z+crBD7r8D3goUO 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: List-Subscribe: List-Unsubscribe: On Thu, 10 Apr 2025 11:57:14 +0800 Baoquan He wrote: > Not like fault_in_readable() or fault_in_writeable(), in > fault_in_safe_writeable() local variable 'start' is increased page > by page to loop till the whole address range is handled. However, > it mistakenly calcalates the size of handled range with 'uaddr - start'. What are the userspace-visible runtime effects of this change?