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[209.85.220.65]) by mx.google.com with SMTPS id r35sor18446062qtr.48.2019.02.06.23.43.13 for (Google Transport Security); Wed, 06 Feb 2019 23:43:13 -0800 (PST) Received-SPF: pass (google.com: domain of bjorn.topel@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=sFQS50W9; spf=pass (google.com: domain of bjorn.topel@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=bjorn.topel@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=hgWiPuQktGDPbFQrOQ3Zw6WnbDS/jHeyLQ4R4JqPa1k=; b=sFQS50W9xOhD0g+DL/NQVoLqngbI0oniG4ARw3FONq4btMQmjVPCfS42/cOhgliKff mHNiWREzOlNAZQQfB6khK4OXLyIVNU1rGp1rC8pYQO2Ya0HHmKAgI8Eavkcfuy55ml52 4olKvAZxp5sN4kexTIBg1uJWLSig2IxB4KSEnMqjYAT8HqAufCATorfSWA1Ao3SjSw3+ 43GvsJRzNyGZUiP9mOD8SxFKHP0lloRYV/lP3gCiNYwtpneDOFTPsilQvoHf8xTrr9jD yNI5rYE4CQQn8CXTriDBXZ/XFInKCk6BrP2/na8mpXw6X/5tobMJ4p8gBT8ORaXuevud g7Gw== X-Google-Smtp-Source: AHgI3IbWQOMVE5pdb7AUDgZmR0M9ALEakMOW8WteZdZIB6Ntsh0TzahDpdKwo1h1zwuIehnKKjj/0e+1Mtl8buJTpho= X-Received: by 2002:ac8:4453:: with SMTP id m19mr855654qtn.303.1549525393551; Wed, 06 Feb 2019 23:43:13 -0800 (PST) MIME-Version: 1.0 References: <20190207053740.26915-1-dave@stgolabs.net> <20190207053740.26915-2-dave@stgolabs.net> In-Reply-To: <20190207053740.26915-2-dave@stgolabs.net> From: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Date: Thu, 7 Feb 2019 08:43:02 +0100 Message-ID: Subject: Re: [PATCH 1/2] xsk: do not use mmap_sem To: Davidlohr Bueso Cc: akpm@linux-foundation.org, linux-mm@kvack.org, LKML , "David S . Miller" , Bjorn Topel , Magnus Karlsson , Netdev , Davidlohr Bueso Content-Type: text/plain; charset="UTF-8" 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: Den tors 7 feb. 2019 kl 06:38 skrev Davidlohr Bueso : > > Holding mmap_sem exclusively for a gup() is an overkill. > Lets replace the call for gup_fast() and let the mm take > it if necessary. > > Cc: David S. Miller > Cc: Bjorn Topel > Cc: Magnus Karlsson > CC: netdev@vger.kernel.org > Signed-off-by: Davidlohr Bueso > --- > net/xdp/xdp_umem.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c > index 5ab236c5c9a5..25e1e76654a8 100644 > --- a/net/xdp/xdp_umem.c > +++ b/net/xdp/xdp_umem.c > @@ -265,10 +265,8 @@ static int xdp_umem_pin_pages(struct xdp_umem *umem) > if (!umem->pgs) > return -ENOMEM; > > - down_write(¤t->mm->mmap_sem); > - npgs =3D get_user_pages(umem->address, umem->npgs, > - gup_flags, &umem->pgs[0], NULL); > - up_write(¤t->mm->mmap_sem); > + npgs =3D get_user_pages_fast(umem->address, umem->npgs, > + gup_flags, &umem->pgs[0]); > Thanks for the patch! The lifetime of the pinning is similar to RDMA umem mapping, so isn't gup_longterm preferred? Bj=C3=B6rn > if (npgs !=3D umem->npgs) { > if (npgs >=3D 0) { > -- > 2.16.4 >