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[209.85.208.175]) by smtp.gmail.com with ESMTPSA id n9sm13990130ljo.89.2020.04.08.10.32.33 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Apr 2020 10:32:33 -0700 (PDT) Received: by mail-lj1-f175.google.com with SMTP id k21so8572397ljh.2 for ; Wed, 08 Apr 2020 10:32:33 -0700 (PDT) X-Received: by 2002:a2e:8911:: with SMTP id d17mr5847808lji.16.1586367152876; Wed, 08 Apr 2020 10:32:32 -0700 (PDT) MIME-Version: 1.0 References: <20200408155924.107722-1-peterx@redhat.com> <20200408172723.GR20730@hirez.programming.kicks-ass.net> In-Reply-To: <20200408172723.GR20730@hirez.programming.kicks-ass.net> From: Linus Torvalds Date: Wed, 8 Apr 2020 10:32:16 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm/gup: Let __get_user_pages_locked() return -EINTR for fatal signal To: Peter Zijlstra Cc: Peter Xu , Linux-MM , Linux Kernel Mailing List , Andrew Morton , Hillf Danton , Thomas Gleixner , syzbot+3be1a33f04dc782e9fd5@syzkaller.appspotmail.com, Michal Hocko Content-Type: text/plain; charset="UTF-8" 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 Wed, Apr 8, 2020 at 10:27 AM Peter Zijlstra wrote: > > > > - if (fatal_signal_pending(current)) > > + if (fatal_signal_pending(current)) { > > + if (!pages_done) > > + pages_done = -EINTR; > > Why -EINTR here and -ERESTARTSYS at the other site? I'd prefer EINTR for all fatal signals. Not because it should matter (it's fatal, after all, the thread should die before it ever sees it), but because I think it's less confusing. If something is fatal, it sure as hell isn't going to restart any system calls. But interrupting things because of fatal signals sounds sane (even if the error code makes it to user space it's interrupting the flow of code). So I'd say that the other place should probably be EINTR too. But it would obviously be a good idea to verify that no caller cares.. Linus Linus