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[209.85.220.65]) by mx.google.com with SMTPS id q202sor559964ywg.190.2019.03.18.07.45.04 for (Google Transport Security); Mon, 18 Mar 2019 07:45:04 -0700 (PDT) Received-SPF: pass (google.com: domain of edumazet@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b="eUd7YMW/"; spf=pass (google.com: domain of edumazet@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=edumazet@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/+Gencg0JswbAigLpd/T2ItS1NnphPhR+c6rD3BwH/4=; b=eUd7YMW/iwbeqVYkUaaw/cUWk71SOkrkn+hXu01mjWUDyol7Y3918h8Me2N/Lmwg82 BACBnVwkosRYGgNkB+MEv3CCkEWOrHu3xf7N5dwYHmmMELnYsQNqsOaeyK88/Ckff/ef kh+B6RhAXAgdrluebHSVHeJbDqxICihTurm6Izpbs8uJk/KpMx9fOP+CQm89PWz1so10 k5Hy+rI3GiWNLVnAFbpLH1eywVv8873JwRYu/a9tdS5LPAoqYign21IdkWCo14GRLZpi +1s6lB6RpgPoZI0uN8BuvtNMRbB8sYv/Hh/TeFFlme7Oddb+rSFYGGHMaF7cYJURP6Fs tbhg== X-Google-Smtp-Source: APXvYqy/LrBuUxgMYxjRei67FuMQP0H17hpJ7z4CK4VwoXLf7Je3qt70qo9gwTM2VSIhDx1PncSnTBxTzploGurMk0s= X-Received: by 2002:a81:2843:: with SMTP id o64mr13821364ywo.441.1552920303807; Mon, 18 Mar 2019 07:45:03 -0700 (PDT) MIME-Version: 1.0 References: <56d3373c1c5007d776fcd5de4523f4b9da341fb6.1552679409.git.andreyknvl@google.com> <04c5b2de-7fde-7625-9d42-228160879ea0@gmail.com> In-Reply-To: From: Eric Dumazet Date: Mon, 18 Mar 2019 07:44:52 -0700 Message-ID: Subject: Re: [PATCH v11 08/14] net, arm64: untag user pointers in tcp_zerocopy_receive To: Andrey Konovalov Cc: Eric Dumazet , Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Linux ARM , "open list:DOCUMENTATION" , Linux Memory Management List , linux-arch , netdev , bpf , "open list:KERNEL SELFTEST FRAMEWORK" , LKML , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy 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, Mar 18, 2019 at 6:17 AM Andrey Konovalov wrote: > > Looking at the code, what's the point of this address != zc->address > check? Should I just remove it? No you must not remove it. The test detects if a u64 ->unsigned long conversion might have truncated bits. Quite surprisingly some people still use 32bit kernels. The ABI is 64bit only, because we did not want to have yet another compat layer. struct tcp_zerocopy_receive { __u64 address; /* in: address of mapping */ __u32 length; /* in/out: number of bytes to map/mapped */ __u32 recv_skip_hint; /* out: amount of bytes to skip */ };