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Fri, 11 Apr 2025 05:32:48 +0000 (UTC) Date: Fri, 11 Apr 2025 13:32:44 +0800 From: Baoquan He To: Andrew Morton , agruenba@redhat.com, gfs2@lists.linux.dev 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: References: <20250410035717.473207-1-bhe@redhat.com> <20250410035717.473207-2-bhe@redhat.com> <20250410204338.4b2101afdf18d8898390ef58@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250410204338.4b2101afdf18d8898390ef58@linux-foundation.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1E2EB80004 X-Stat-Signature: 8g637nsob8y9847nwd7baxps9y3wbcic X-Rspam-User: X-HE-Tag: 1744349574-559943 X-HE-Meta: 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 YcyGCbT3 R8BxzXoc78AjmEW1gHgHeFgVcfKJQFDvhprivCdHyJOR/Dwd/WS95kfUwnOegoLy0YQeoTehWdRizIBoZL0Xi16FmnaKo15rPBdYkuOd+ViqSnDw697lOhTL62OAjafXpWo4i3F7+CzGh7aJ3M6yjEIE1cVZO8AXcEYqZqbpDG/UR9IILm1uxa8nx4Qasuz38X0aF7bPWgEDbuOSlq511K6OCwa8cRvT+sG/DVtbJE510hnIaKodFfhZypAD5LELcVaL7VnEMRelhHdUrdQL/KwNgfSB7ia6vaA0DIvJMrjcAPqYSLpB/ZnenUklqmjxRajFx31Ca99bMrWG47lBSfGXiny5hbc1agTyjK0Be4xtgTAiAZhiSxA7xIXoL+BP4jy2Tnsd9d8u7fxFztqdC6TP1g0ApKogVw6Ws4y2LTKHjndIZcwOcI7aJyBNh+XjepSFdsFIluRXUC8SN75YNP6lpAOf4BIcagFIg 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 04/10/25 at 08:43pm, Andrew Morton wrote: > 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? I see it mainly affect gfs2_file_direct_read(). Not sure if GFS2 people can sense any exceptional behaviour caused by this code bug. >