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([2001:b07:6468:f312:5d12:7fa9:fb2d:7edb]) by smtp.gmail.com with ESMTPSA id f134sm1257977wmg.20.2019.08.13.02.29.09 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 13 Aug 2019 02:29:10 -0700 (PDT) Subject: Re: DANGER WILL ROBINSON, DANGER To: Matthew Wilcox , =?UTF-8?Q?Adalbert_Laz=c4=83r?= Cc: kvm@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Konrad Rzeszutek Wilk , Tamas K Lengyel , Mathieu Tarral , =?UTF-8?Q?Samuel_Laur=c3=a9n?= , Patrick Colp , Jan Kiszka , Stefan Hajnoczi , Weijiang Yang , Zhang@kvack.org, Yu C , =?UTF-8?Q?Mihai_Don=c8=9bu?= , =?UTF-8?Q?Mircea_C=c3=aerjaliu?= References: <20190809160047.8319-1-alazar@bitdefender.com> <20190809160047.8319-72-alazar@bitdefender.com> <20190809162444.GP5482@bombadil.infradead.org> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Tue, 13 Aug 2019 11:29:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190809162444.GP5482@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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 09/08/19 18:24, Matthew Wilcox wrote: > On Fri, Aug 09, 2019 at 07:00:26PM +0300, Adalbert Laz=C4=83r wrote: >> +++ b/include/linux/page-flags.h >> @@ -417,8 +417,10 @@ PAGEFLAG(Idle, idle, PF_ANY) >> */ >> #define PAGE_MAPPING_ANON 0x1 >> #define PAGE_MAPPING_MOVABLE 0x2 >> +#define PAGE_MAPPING_REMOTE 0x4 > Uh. How do you know page->mapping would otherwise have bit 2 clear? > Who's guaranteeing that? >=20 > This is an awfully big patch to the memory management code, buried in > the middle of a gigantic series which almost guarantees nobody would > look at it. I call shenanigans. Are you calling shenanigans on the patch submitter (which is gratuitous) or on the KVM maintainers/reviewers? It's not true that nobody would look at it. Of course no one from linux-mm is going to look at it, but the maintainer that looks at the gigantic series is very much expected to look at it and explain to the submitter that this patch is unacceptable as is. In fact I shouldn't have to to explain this to you; you know better than believing that I would try to sneak it past the mm folks. I am puzzled. Paolo