From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 25250C433EF for ; Thu, 18 Nov 2021 19:22:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F4CF610F8 for ; Thu, 18 Nov 2021 19:22:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232554AbhKRTZy (ORCPT ); Thu, 18 Nov 2021 14:25:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231381AbhKRTZy (ORCPT ); Thu, 18 Nov 2021 14:25:54 -0500 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01948C061574; Thu, 18 Nov 2021 11:22:54 -0800 (PST) Received: by mail-pg1-x543.google.com with SMTP id 206so1268164pgb.4; Thu, 18 Nov 2021 11:22:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=9DwYPEuVSdd48njM32+CTEoTL5NcWu+kd/UXfUNYqNA=; b=PxoIvjhLE8yD5/colNf5+K2IUwNlaiSNkpSJhn92x7ZEAd5zKU/Kjk+YwoOI/d07x3 RzxuH7OiR6s8l7DEtKrV9F3xTJ3FM6zkDxxKX4HNIdsped7obh9+5ZOKVTsrDcMGm90U eUYp+mXiQrcZy1zeVhTIMJ3Cd7+nNC1YQf9TvJoGFwZNwiyORVWpzH09loOw0LkXcCmh hHTqH9ICalJjO6bNLSjZwmc1hVGEoWwMZap4FHngnMxergk7At+A5+KDCAn2aL0VuZIj SKw7ouFSYETvynkd/byLw5dmo+CbvPrXkrT0joCorh/CBWEwZuSPeMI13UYjG9CTEBOu IDvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=9DwYPEuVSdd48njM32+CTEoTL5NcWu+kd/UXfUNYqNA=; b=B23LWfqkhLMS2r8OdOgPI2i35679HHxi2foriPT/EDaMZ5gXa1l51QI8MfZIOTlvcG r7gM7JCmkqo/Frb/jaRa+5ewX7a/+YQ6lg3CArl1PTxNcuqJ6yFkQ9oGj/kDlCUzLsM0 CKBjTuWwdNmekKluVRO2bnwo104xU7g1xwCo6/7DksEIXgC68gRWj5ZZBcZyZgkDi9IP 84vHNikFrMye/a235pDfxsPXaN4suUKDQyvtoRh7rU4J/Vpi5rmuAfXH2+2Ys6o8Q6MA YWg77fz+Ti968Zp7v/+mDRmrpYLYv/IB6W6YNi6l2lc30A0JIEK87DPJDhQdV5Iao/Dn SFew== X-Gm-Message-State: AOAM5300kmOfZonCx5075TUh1AGZ8K+xmTj/dOOjaIql/TrLb+G5XkAe jdhGWmXLPIshKsqC9ibs1FY= X-Google-Smtp-Source: ABdhPJx4J59KcZh//S44pDR3o7vIblqZR/9qmk8K0W5n2pI+QRJt6oHWMipVHSTfO0A/zLwp97S9wA== X-Received: by 2002:a63:5961:: with SMTP id j33mr13068515pgm.56.1637263373511; Thu, 18 Nov 2021 11:22:53 -0800 (PST) Received: from localhost ([2405:201:6014:d064:502e:73f4:8af1:9522]) by smtp.gmail.com with ESMTPSA id g17sm370500pfv.136.2021.11.18.11.22.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Nov 2021 11:22:53 -0800 (PST) Date: Fri, 19 Nov 2021 00:52:50 +0530 From: Kumar Kartikeya Dwivedi To: Yonghong Song Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Pavel Emelyanov , Alexander Mihalicyn , Andrei Vagin , criu@openvz.org, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH bpf-next v1 2/8] bpf: Add bpf_page_to_pfn helper Message-ID: <20211118192250.izzbajkorok6hvsv@apollo.localdomain> References: <20211116054237.100814-1-memxor@gmail.com> <20211116054237.100814-3-memxor@gmail.com> <7efcf912-46be-1ed4-7e12-88c2baeaab12@fb.com> <20211118183022.tiijkhno57uwtytm@apollo.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Fri, Nov 19, 2021 at 12:48:39AM IST, Yonghong Song wrote: > > > On 11/18/21 10:30 AM, Kumar Kartikeya Dwivedi wrote: > > On Thu, Nov 18, 2021 at 10:57:15PM IST, Yonghong Song wrote: > > > > > > > > > On 11/15/21 9:42 PM, Kumar Kartikeya Dwivedi wrote: > > > > In CRIU, we need to be able to determine whether the page pinned by > > > > io_uring is still present in the same range in the process VMA. > > > > /proc//pagemap gives us the PFN, hence using this helper we can > > > > establish this mapping easily from the iterator side. > > > > > > > > It is a simple wrapper over the in-kernel page_to_pfn helper, and > > > > ensures the passed in pointer is a struct page PTR_TO_BTF_ID. This is > > > > obtained from the bvec of io_uring_ubuf for the CRIU usecase. > > > > > > > > Signed-off-by: Kumar Kartikeya Dwivedi > > > > --- > > > > fs/io_uring.c | 17 +++++++++++++++++ > > > > include/linux/bpf.h | 1 + > > > > include/uapi/linux/bpf.h | 9 +++++++++ > > > > kernel/trace/bpf_trace.c | 2 ++ > > > > scripts/bpf_doc.py | 2 ++ > > > > tools/include/uapi/linux/bpf.h | 9 +++++++++ > > > > 6 files changed, 40 insertions(+) > > > > > > > > diff --git a/fs/io_uring.c b/fs/io_uring.c > > > > index 46a110989155..9e9df6767e29 100644 > > > > --- a/fs/io_uring.c > > > > +++ b/fs/io_uring.c > > > > @@ -11295,6 +11295,23 @@ static struct bpf_iter_reg io_uring_buf_reg_info = { > > > > .seq_info = &bpf_io_uring_buf_seq_info, > > > > }; > > > > +BPF_CALL_1(bpf_page_to_pfn, struct page *, page) > > > > +{ > > > > + /* PTR_TO_BTF_ID can be NULL */ > > > > + if (!page) > > > > + return U64_MAX; > > > > + return page_to_pfn(page); > > > > +} > > > > + > > > > +BTF_ID_LIST_SINGLE(btf_page_to_pfn_ids, struct, page) > > > > + > > > > +const struct bpf_func_proto bpf_page_to_pfn_proto = { > > > > + .func = bpf_page_to_pfn, > > > > + .ret_type = RET_INTEGER, > > > > + .arg1_type = ARG_PTR_TO_BTF_ID, > > > > + .arg1_btf_id = &btf_page_to_pfn_ids[0], > > > > > > Does this helper need to be gpl_only? > > The typically guideline whether the same info can be retrieved from > userspace. If yes, no gpl is needed. Otherwe, it needs to be gpl. > I think it can already be obtained using /proc//pagemap, so not needed. > Also, the helper is implemented in io_uring.c and the helper > is used by tracing programs. Maybe we can put the helper > in bpf_trace.c? The helper itself is not tied to io_uring, right? > Right, I'll move it outside CONFIG_IO_URING in v2. That's also why the build failed on this patch. -- Kartikeya