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Sun, 30 Mar 2025 22:48:36 +0000 (UTC) Received: from localhost (unknown [10.72.112.9]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 38301180B492; Sun, 30 Mar 2025 22:48:34 +0000 (UTC) Date: Mon, 31 Mar 2025 06:48:25 +0800 From: Baoquan He To: Zhu Yanjun Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/7] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Message-ID: References: <20250330121718.175815-1-bhe@redhat.com> <20250330121718.175815-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspamd-Queue-Id: 0A76E1C0004 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 7r4ee7khtx5q5ge9fq9r16haoz9xwi8i X-HE-Tag: 1743374921-566548 X-HE-Meta: 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 B3Bo7gY3 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 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 03/30/25 at 09:43pm, Zhu Yanjun wrote: > 在 2025/3/30 14:17, Baoquan He 写道: > > Not like fault_in_writeable() or fault_in_writeable(), in > fault_in_readable()? > > In the above, one of the 2 fault_in_writeable should be fault_in_readable() > ? You are right, I will fix it in v2. Thanks. > > 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'. > > > > Fix it here. > > > > Signed-off-by: Baoquan He > > --- > > mm/gup.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/gup.c b/mm/gup.c > > index 855ab860f88b..73777b1de679 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -2207,8 +2207,8 @@ size_t fault_in_safe_writeable(const char __user *uaddr, size_t size) > > } while (start != end); > > mmap_read_unlock(mm); > > - if (size > (unsigned long)uaddr - start) > > - return size - ((unsigned long)uaddr - start); > > + if (size > start - (unsigned long)uaddr) > > + return size - (start - (unsigned long)uaddr); > > return 0; > > } > > EXPORT_SYMBOL(fault_in_safe_writeable); > >