From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08A0BC36014 for ; Tue, 1 Apr 2025 14:12:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 91C9C280004; Tue, 1 Apr 2025 10:11:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8CFA5280002; Tue, 1 Apr 2025 10:11:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 76CF6280004; Tue, 1 Apr 2025 10:11:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 54979280002 for ; Tue, 1 Apr 2025 10:11:59 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id E67A2A80EF for ; Tue, 1 Apr 2025 14:11:59 +0000 (UTC) X-FDA: 83285663958.25.E760711 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf27.hostedemail.com (Postfix) with ESMTP id 0CE4A40010 for ; Tue, 1 Apr 2025 14:11:57 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=H58zNYJo; spf=pass (imf27.hostedemail.com: domain of bhe@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1743516718; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=suAxeaNpOjK2xWYvWoyiGhS57tRLw1UbrXfTqrCY4sY=; b=o+kBPm+BwsLPJtw3NYFCZtcQkvRlgcGxi5UFzyaYwZCPJY5rs4urq9j3KqKIpVeYTayx7q MMs2c9ZSsdaA2DhW22YK/8h4HYgcT4kymbXmmUxwK5ld4lJkEwth9Etn1EPxm1ac9MsAYh bEo212/BE2D0PTH430zWpX29is5Z4n8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1743516718; a=rsa-sha256; cv=none; b=aGrtDfCB51kuRha4Ajr/ix8Fw6QEtkxB4ImXw6azwdULXsIH/KZ7C6CioVbQX+slCUW7fA TgQBL1IJZ6chCFfE8iR19rehVHlIBym9+NHiZ9Mx9EyCoO68zaLniz/a6aov7m30AlzqGT pMjCBSjCjlQzH3Oj/FW8kiJIMufjGH8= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=H58zNYJo; spf=pass (imf27.hostedemail.com: domain of bhe@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743516717; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=suAxeaNpOjK2xWYvWoyiGhS57tRLw1UbrXfTqrCY4sY=; b=H58zNYJohPPrJxMZL0xhNTOMv85OSVgvL7gY33EgUjCJEnXVr+JgO0xAgZ8V+PZewPjrXX Jz+0qvnM13+JSeoWpLxx1mdNdUbl+ld++hJZ9Cbb99P7N3y3+hw/s7Yg0Ta+RHqugbU9u8 jsZTknCpYMyFPxBKK4k/w4fLWv6e/e0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-423-5HaEc5wiP2Cp8mbFAb_PfA-1; Tue, 01 Apr 2025 10:11:54 -0400 X-MC-Unique: 5HaEc5wiP2Cp8mbFAb_PfA-1 X-Mimecast-MFC-AGG-ID: 5HaEc5wiP2Cp8mbFAb_PfA_1743516713 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E6E14180882E; Tue, 1 Apr 2025 14:11:52 +0000 (UTC) Received: from localhost (unknown [10.72.112.12]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1F6481955D81; Tue, 1 Apr 2025 14:11:50 +0000 (UTC) Date: Tue, 1 Apr 2025 22:11:46 +0800 From: Baoquan He To: David Hildenbrand Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yanjun.zhu@linux.dev Subject: Re: [PATCH v2 1/7] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Message-ID: References: <20250331081327.256412-1-bhe@redhat.com> <20250331081327.256412-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0CE4A40010 X-Stat-Signature: p9yo47gm9n6unixoz6x6fm1zzbcaiyk1 X-HE-Tag: 1743516717-752227 X-HE-Meta: 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 wyYmXADi mQ/WsqvyRmfhYyR236RWsZa5J0WU5WkrHIAJXbf4eaYpmPcm3GgaO/1A6+RlXe67gRMHBHcImUrSQ9IhVC6SjUMhsOMjcr5/J2FxaAoDhZYbJu7SFM2vA1se3/zo/EDyURQmf/Us/gF6j9KoWkbL+cMnvc0mls8q4eN+hUMAh/5GLDQcFezgywkAiFh6nIQ7jgIDZmLP4HOSI+4UQ3NLvFw7Ze2Jgq/5ErkByrmYaOEFGbyu3B03HjhhRoyCxLKJPZBtrMNQPMxitJR0jIuZRWvtad8IJnkG5Gw3rQZ8Yjy852WljV+RZjmNNuC8mwgrJyuttbjLJb7jvS156x20GbB4uavclLpYFPcF/vrQLc3ZDbN+qef4W/IJRzCei+JhMcbBPC4P1vVjV0n6wTpBVF1gQMPFADVYZRFDdBG6XvBXgd8+5slvHvOazBzQuBGRa5+HVS9PmLfuTX7MBkkgvXUkmLJ3f3XS33oiw 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 04/01/25 at 10:10am, David Hildenbrand wrote: > On 31.03.25 10:13, 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'. > > > > Fix it here. > > Fixes: ? Do we know of user-visible effects? I believe it should impact, while I didn't hear of any complaint. Yeah, it's worth to have one Fixes. > > > > > Signed-off-by: Baoquan He > > --- > > v1->v2: > > - Fix a patch log typo caused by copy-and-paste error. Thanks > > to Yanjun. > > > > 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); > > Can we instead just use the uaddr and start variables like in > fault_in_readable? > > That is, turn "start" into a const and adjust uaddr instead. Sounds good to me, that makes these similar blocks own consistent code style. Will change in v3. Thanks for reviewing. > > (maybe we should also handle the types of these variables similar to as in > fault_in_readable) > > -- > Cheers, > > David / dhildenb >