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[209.85.208.172]) by smtp.gmail.com with ESMTPSA id n1sm1531626lfl.77.2019.06.24.06.40.00 for (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jun 2019 06:40:00 -0700 (PDT) Received: by mail-lj1-f172.google.com with SMTP id v18so12644121ljh.6 for ; Mon, 24 Jun 2019 06:40:00 -0700 (PDT) X-Received: by 2002:a2e:95d5:: with SMTP id y21mr63467183ljh.84.1561383118160; Mon, 24 Jun 2019 06:31:58 -0700 (PDT) MIME-Version: 1.0 References: <20190620022008.19172-1-peterx@redhat.com> <20190620022008.19172-3-peterx@redhat.com> <20190624074250.GF6279@xz-x1> In-Reply-To: <20190624074250.GF6279@xz-x1> From: Linus Torvalds Date: Mon, 24 Jun 2019 21:31:42 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 02/25] mm: userfault: return VM_FAULT_RETRY on signals To: Peter Xu Cc: Linux-MM , Linux List Kernel Mailing , David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , Shaohua Li , Andrea Arcangeli , Mike Kravetz , Marty McFadden , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" 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 Mon, Jun 24, 2019 at 3:43 PM Peter Xu wrote: > > Should we still be able to react on signal_pending() as part of fault > handling (because that's what this patch wants to do, at least for an > user-mode page fault)? Please kindly correct me if I misunderstood... I think that with this patch (modulo possible fix-ups) then yes, as long as we're returning to user mode we can do signal_pending() and return RETRY. But I think we really want to add a new FAULT_FLAG_INTERRUPTIBLE bit for that (the same way we already have FAULT_FLAG_KILLABLE for things that can react to fatal signals), and only do it when that is set. Then the page fault handler can set that flag when it's doing a user-mode page fault. Does that sound reasonable? Linus