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 A97395228 for ; Wed, 26 Jul 2023 08:55:51 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52EFB4237 for ; Wed, 26 Jul 2023 01:55:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1690361745; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=XtYwhjvqgWz9QjsOakEd2O0h4kwm2uV/DxKMgZHITXQ=; b=gR90ZHTsIFPJbAg2V6QtHYtdEIqf2mztrfr0Mgys9KrMhyuyY0t/FSMznnqYIoC/FdnCJ5 UleAVqbAVPU/Q6qM/4fPFnhkhvDrswBoaCVTV7NFetsh8GE+y7msa1LmcZgi2YxDl9X7Ik EcWj1iqRLydknv2UFssVsyJgK70VqtA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-80--kpPVwcUMIqEd3se6Fhlag-1; Wed, 26 Jul 2023 04:55:42 -0400 X-MC-Unique: -kpPVwcUMIqEd3se6Fhlag-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id AE08D803470; Wed, 26 Jul 2023 08:55:41 +0000 (UTC) Received: from fedora.. (unknown [10.43.17.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4A4754094DC0; Wed, 26 Jul 2023 08:55:40 +0000 (UTC) From: tglozar@redhat.com To: linux-kernel@vger.kernel.org Cc: john.fastabend@gmail.com, jakub@cloudflare.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, bpf@vger.kernel.org, Tomas Glozar Subject: [PATCH RFC net] bpf: sockmap: Remove preempt_disable in sock_map_sk_acquire Date: Wed, 26 Jul 2023 10:50:03 +0200 Message-ID: <20230726085003.261112-1-tglozar@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,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 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") with no comment on why it is necessary. Remove preempt_disable to fix BUG in sock_map_update_common on RT. Signed-off-by: Tomas Glozar --- net/core/sock_map.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 19538d628714..08ab108206bf 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -115,7 +115,6 @@ static void sock_map_sk_acquire(struct sock *sk) __acquires(&sk->sk_lock.slock) { lock_sock(sk); - preempt_disable(); rcu_read_lock(); } @@ -123,7 +122,6 @@ static void sock_map_sk_release(struct sock *sk) __releases(&sk->sk_lock.slock) { rcu_read_unlock(); - preempt_enable(); release_sock(sk); } base-commit: 22117b3ae6e37d07225653d9ae5ae86b3a54f99c -- 2.39.3