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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C9B1C001DE for ; Mon, 31 Jul 2023 09:28:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229965AbjGaJ2x (ORCPT ); Mon, 31 Jul 2023 05:28:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229552AbjGaJ2v (ORCPT ); Mon, 31 Jul 2023 05:28:51 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 957B710D for ; Mon, 31 Jul 2023 02:28:49 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id a640c23a62f3a-99c136ee106so138435866b.1 for ; Mon, 31 Jul 2023 02:28:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; t=1690795728; x=1691400528; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:from:to:cc:subject:date:message-id:reply-to; bh=wtH3YJMD11ClFBOSnTSJccRhxUCi2rBb0qglhfD80e4=; b=hpEhwkYRUgPwcYiX5zoW238M0RpToVCkf2zw8CHjXVjUcpOhbFkx44f6DRF2fH3C/O kIL36gVAKuHoEpU24X+lAGQ3NWBEAKledAPHkMu3sx53L6rTxWDl+x8mnjdn0ZH7kSml s1ZDnBF/acdwWm6mCquKVy5KmvlDNEr+SnAjI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690795728; x=1691400528; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=wtH3YJMD11ClFBOSnTSJccRhxUCi2rBb0qglhfD80e4=; b=bcSLTTAufdz4SiTqv1CbrNTn9xKf67y+s2HX0Bv7g1yViVu7lBhMkbFUi/M89and8C Is+8ag6i8A3zyOQdyDjZJ9Mc0HK9RETvfiXzw97KlD3iObufYZc2DA8wvpTSQd+1qqKo 9cKhwXgGFapCzRR4fCOZmWzmLjnyuDjgxf5t+qyvDErwRk3ftAvOjbwY66uhHNB8az1P dK4Cqhlb86o1uWfJPm2Fge+SNybmMWKFTgjJWVX1vshsnyck0B6zgqHBWyQRe6+sHzeI 4Buuu8xvs8JlHAA2y0RFXUXnfQkELJ2Pm503aAFQfDC2Fn8LFow8y7cd+xz44lB04NiC mCVQ== X-Gm-Message-State: ABy/qLZNbrgWNUVr3RPmLNtenDmqcX5gYHYg+CCWaku6Xxo7q0u7rhe8 lfBuYkKeMvJe4qQR9Jzp4ue8RA== X-Google-Smtp-Source: APBJJlH5vz9bIOjc/NhazbMjjsF4NHsoCSJFQ/SXvy3HcL+W4PkPGZj3rOCrhgK6jwYyNkWtfd8x7A== X-Received: by 2002:a17:906:1053:b0:99c:441:ffa with SMTP id j19-20020a170906105300b0099c04410ffamr5972053ejj.29.1690795728002; Mon, 31 Jul 2023 02:28:48 -0700 (PDT) Received: from cloudflare.com (79.184.136.135.ipv4.supernova.orange.pl. [79.184.136.135]) by smtp.gmail.com with ESMTPSA id a11-20020a17090680cb00b009892cca8ae3sm5856176ejx.165.2023.07.31.02.28.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jul 2023 02:28:47 -0700 (PDT) References: <20230728064411.305576-1-tglozar@redhat.com> User-agent: mu4e 1.6.10; emacs 28.2 From: Jakub Sitnicki To: tglozar@redhat.com Cc: linux-kernel@vger.kernel.org, john.fastabend@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH net] bpf: sockmap: Remove preempt_disable in sock_map_sk_acquire Date: Mon, 31 Jul 2023 11:16:12 +0200 In-reply-to: <20230728064411.305576-1-tglozar@redhat.com> Message-ID: <87ila0fn01.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 28, 2023 at 08:44 AM +02, tglozar@redhat.com wrote: > From: Tomas Glozar > > Disabling preemption in sock_map_sk_acquire conflicts with GFP_ATOMIC > allocation later in sk_psock_init_link on PREEMPT_RT kernels, since > GFP_ATOMIC might sleep on RT (see bpf: Make BPF and PREEMPT_RT co-exist > patchset notes for details). > > This causes calling bpf_map_update_elem on BPF_MAP_TYPE_SOCKMAP maps to > BUG (sleeping function called from invalid context) on RT kernels. > > preempt_disable was introduced together with lock_sk and rcu_read_lock > in commit 99ba2b5aba24e ("bpf: sockhash, disallow bpf_tcp_close and update > in parallel"), probably to match disabled migration of BPF programs, and > is no longer necessary. > > Remove preempt_disable to fix BUG in sock_map_update_common on RT. > > Signed-off-by: Tomas Glozar > --- We disable softirq and hold a spin lock when modifying the map/hash in sock_{map,hash}_update_common so this LGTM: Reviewed-by: Jakub Sitnicki You might want some extra tags: Link: https://lore.kernel.org/all/20200224140131.461979697@linutronix.de/ Fixes: 99ba2b5aba24 ("bpf: sockhash, disallow bpf_tcp_close and update in parallel")