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 X-Spam-Level: X-Spam-Status: No, score=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6701AC433FE for ; Wed, 8 Sep 2021 18:15:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 192426115B for ; Wed, 8 Sep 2021 18:15:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 192426115B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 92D296B0071; Wed, 8 Sep 2021 14:15:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8DCB36B0072; Wed, 8 Sep 2021 14:15:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7A4926B0073; Wed, 8 Sep 2021 14:15:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0194.hostedemail.com [216.40.44.194]) by kanga.kvack.org (Postfix) with ESMTP id 62E916B0071 for ; Wed, 8 Sep 2021 14:15:30 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 04D002FD9F for ; Wed, 8 Sep 2021 18:15:30 +0000 (UTC) X-FDA: 78565208820.38.00AD4E6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf13.hostedemail.com (Postfix) with ESMTP id A410D1029BDA for ; Wed, 8 Sep 2021 18:15:29 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 656E861100; Wed, 8 Sep 2021 18:15:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1631124928; bh=G9enD3BK6oGuRKGWCXkTjniebaPc0KdYuaPPqV3q80A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cTCIvgQSGjSt3cQVQO+EYTwnCE7lZr9v5WJ45kCaDFBRIVj4Od7K/Sjw1RmONruHS HIxFkdeaP5W5q6xJaDLGA48LlwveR9X+FiKpN0fhmz3WPo93US8uuH7kWhviOKbuiL FF6ek7PEYgI5G5hqZnBZCticc2GNpACi84cC2mT8= Date: Wed, 8 Sep 2021 11:15:27 -0700 From: Andrew Morton To: Alexei Starovoitov Cc: Luigi Rizzo , Yonghong Song , Liam Howlett , Peter Zijlstra , Jason Gunthorpe , Daniel Borkmann , Michel Lespinasse , bpf , "linux-mm@kvack.org" , Alexei Starovoitov , Andrii Nakryiko , "kernel-team@fb.com" Subject: Re: [PATCH mm/bpf v2] mm: bpf: add find_vma_no_check() without lockdep_assert on mm->mmap_lock Message-Id: <20210908111527.9a611426e257d55ccbbf46eb@linux-foundation.org> In-Reply-To: <20210908180258.yjh62e5oouckar5b@ast-mbp.dhcp.thefacebook.com> References: <20210908044427.3632119-1-yhs@fb.com> <20210908135326.GZ1200268@ziepe.ca> <20210908151230.m2zyslt4qrufm4bv@revolver> <20210908172118.n2f4w7epm6hh62zf@ast-mbp.dhcp.thefacebook.com> <20210908105259.c47dcc4e4371ebb5e147ee6e@linux-foundation.org> <20210908180258.yjh62e5oouckar5b@ast-mbp.dhcp.thefacebook.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A410D1029BDA X-Stat-Signature: sktz3dwj4azbzhm719xnswaxhjfyiptx Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=cTCIvgQS; spf=pass (imf13.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-HE-Tag: 1631124929-143112 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, 8 Sep 2021 11:02:58 -0700 Alexei Starovoitov wrote: > > Please describe the expected userspace-visible change from Peter's > > patch in full detail? > > User space expects build_id to be available. Peter patch simply removes > that feature. Are you sure? He ends up with static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u64 *ips, u32 trace_nr, bool user) { int i; /* cannot access current->mm, fall back to ips */ for (i = 0; i < trace_nr; i++) { id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); } return; } and you're saying that userspace won't like this because we didn't set BPF_STACK_BUILD_ID_VALID?