From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 367A11426B for ; Mon, 31 Jul 2023 09:28:51 +0000 (UTC) Received: from mail-ed1-x530.google.com (mail-ed1-x530.google.com [IPv6:2a00:1450:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9616111A for ; Mon, 31 Jul 2023 02:28:49 -0700 (PDT) Received: by mail-ed1-x530.google.com with SMTP id 4fb4d7f45d1cf-522bc9556f5so2213903a12.0 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=j5piyoZ4gUWJe0Uhv8KquexQkp3XHEC007rxBCg2kRMZIJi+BNtfN3YSfWKIG7L/h6 4Ch7eUZNzA1JN9w95z55CvSEuGPW968go7J5UG6w8fS/IkMCKrXXqyhbU6mSGk8wEHT3 Eu6gBqni3zmltaNpwRLXff1F1rlxFjH1yMwyzp0SuWbvLH1mojvPT970tfjTKnsaKQW5 AYOKjAXfwKnOD3EvtLB1pGF7CqUQ7tgxGdgvv14rnMpfbWxh2IBQRZGtaYbblNOVnwK3 iCmzoV6QojCUinqCjsv5SfoVPJ7mTSJr/BThl2dIKZy1oQgAhnbymQ14MZrRUmwQm9xz XaNQ== X-Gm-Message-State: ABy/qLaIAahvhIsZ81AJqbSSt66WV2fh8gEZmWc9jOo5ACA48Ug42lKw SYzTEWEtL9Fl7GXcddmluiGu9bAn5lhPyETH/s8= 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> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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")