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[209.85.208.169]) by smtp.gmail.com with ESMTPSA id 12-v6sm8771054ljs.29.2018.12.28.13.09.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Dec 2018 13:09:05 -0800 (PST) Received: by mail-lj1-f169.google.com with SMTP id q2-v6so19594447lji.10 for ; Fri, 28 Dec 2018 13:09:05 -0800 (PST) X-Received: by 2002:a2e:9c7:: with SMTP id 190-v6mr11608679ljj.120.1546031345296; Fri, 28 Dec 2018 13:09:05 -0800 (PST) MIME-Version: 1.0 References: <1542702858-4318-1-git-send-email-wanpengli@tencent.com> <442fc8ca-f92c-eded-9ede-c800a03bf39a@redhat.com> In-Reply-To: From: Linus Torvalds Date: Fri, 28 Dec 2018 13:08:49 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] KVM: X86: Fix scan ioapic use-before-initialization To: Dmitry Vyukov Cc: Paolo Bonzini , LKML , Wanpeng Li , Greg Kroah-Hartman , dledford@redhat.com, KVM list , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Wei Wu , Kostya Serebryany , Daniel Vetter , syzkaller , Dan Williams , Chris Mason , Jonathan Corbet , Kees Cook , Laura Abbott , Olof Johansson , Steven Rostedt , Theodore Tso , Tim.Bird@sony.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 28, 2018 at 1:43 AM Dmitry Vyukov wrote: > > > Nobody reads the kernel mailing list directly - there's just too much traffic. > > As the result bug reports and patches got lots and this is bad and it > would be useful to stop it from happening and there are known ways for > this. Well, let me be a bit more specific: you will find that people read the very _targeted_ mailing lists, because they not only tend to be more specific to some particular interest, but also aren't the flood of hundreds of emails a day. And don't get me wrong: I'm not saying that lkml is useless. Not at all. It's just that it's really more of an archival model than a "people read it" - so you send your emails to a group of people, and then you cc lkml so that when that group gets expanded people can be pointed at the whole thread. Or, obviously, so that commit messages etc can point to discussion. But that does mean that any lkml cc shouldn't be expected to cause a reaction in itself. It's about other things. > syzbot not doing bisection is not the root cause of this Root case? No. But if you do bisection, it means that you can now target things much better. So then it's not lkml and "random collection of maintainers", but a much more targeted group. And that targeted group also ends up being a lot more receptive to it. Again, look at the raw syzbot email and the email by Wanpeng Li. Yes, the syzbot email did bring in a reasonable set of people just based on the oops (I think it did "get_mainainter" on kvm_ioapic_scan_entry()). But Wangpeng ended up sending it to the *particular* people who were directly responsible. > 2. syzbot reports are not worse then average human reports, frequently better. No, they really aren't. They are better in a *technical* sense, but they are also very much obviously automated, which makes the target people take them much less seriously. When you see lots of syzbot emails, and there are lots of more or less random recipients that may or may not be correct, what's the natural reaction to that? Look up "bystander effect". > 3. Bisection is useful, but not important in most cases. No. Exactly because of the problem syzbot has. It's too scatter-shot. People clearly ignore it, because people feel it's not _their_ issue. The advantage of bisection is that it makes the problem much more specific. Right now, you'll find that many developers ignore syzbot simply because it's not worth their time to chase down whether it's even their problem. See what I'm saying? It's the whole "data vs information" issue. Particularly when cc'ing maintainers, who get hundreds of emails a day, you need to convince them that this email is _relevant_. Linus