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=-12.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 25096C433DF for ; Fri, 9 Oct 2020 12:48:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6EBA222B8 for ; Fri, 9 Oct 2020 12:48:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="YzZHxFMx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732410AbgJIMsW (ORCPT ); Fri, 9 Oct 2020 08:48:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:60487 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732380AbgJIMsW (ORCPT ); Fri, 9 Oct 2020 08:48:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602247700; 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=Ma9SFMzdkJ5yBVRsnLxMjp1y9pGoX30Pnen2ZZiqr2c=; b=YzZHxFMx92JG+gEAjgwJAQeT7/csjBqPOVm8xaVdBq8j4NcmWZLUfo/+dwhp7JoUElMLhg udGZhp0UaZ4CULGTH1mVAR7rdLBxT6PGSWRTfupeLhH7GRiicUgCX5n6quhqjh/xvXDgZj vKPfr7/r3DCpDC54059Gr/spDKAjzNQ= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-400-fMFfU50YP36gxb9f65J4Gg-1; Fri, 09 Oct 2020 08:48:18 -0400 X-MC-Unique: fMFfU50YP36gxb9f65J4Gg-1 Received: by mail-wr1-f72.google.com with SMTP id i10so5179094wrq.5 for ; Fri, 09 Oct 2020 05:48:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Ma9SFMzdkJ5yBVRsnLxMjp1y9pGoX30Pnen2ZZiqr2c=; b=QzO+fC8Y3hxBPbaL5etgbgzKvIPr1K0537uePdZSOC73eN/pdvTQANK8TLykrJCSNO VZkoNdsqij6mepnhiY67hLeHKbIM8PDWEPRJ2UDc1RZaK7JuvIZw4aEBqUlHN/qD0RPJ 0d4zCbyF5N9brnXoyYYPa8/DSjEbC9sh4vpT7EAqEl/4abOu3VPpdE3u8dPVZYF3ADrJ XEUG5YJ7GYJnbT/XC1hW41RfXg5lQiKECyaxMDd7DNGacYguLYzevsQwjDKvE+kLkUpd 2GOotqmH8UeC1Jz6qEqbQR5PF4VK0zHATIDpmDe0Vu5vPSRp8a3/ghebUFnmcDvuUaxT JSkw== X-Gm-Message-State: AOAM532IfID3sOiur8QJOdjGIlpSeP9R37XJVfSfR5dRQlxGmb7jYz0T AiU6OwyjFeg/OqIU8ZaLy/Nhsa+fHB7Zkg4X21sZHX9rc24zhc+876HYLk4pi5jWNxndIT/SgLB eeK0XF4eFNZqFZI217Bzd87ocEo0= X-Received: by 2002:a1c:dd0b:: with SMTP id u11mr13791370wmg.186.1602247697165; Fri, 09 Oct 2020 05:48:17 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy/SF4ChAJKbRcFTapWkvjhgpreOJnLpLJRd4p4YON4As2iwS/TFebC8I8ajLwpyNDeDdDSDg== X-Received: by 2002:a1c:dd0b:: with SMTP id u11mr13791343wmg.186.1602247696899; Fri, 09 Oct 2020 05:48:16 -0700 (PDT) Received: from localhost.localdomain.com ([151.29.23.182]) by smtp.gmail.com with ESMTPSA id j13sm12542411wru.86.2020.10.09.05.48.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 05:48:16 -0700 (PDT) From: Juri Lelli To: tglx@linutronix.de, bigeasy@linutronix.de Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, bristot@redhat.com, williams@redhat.com, echaudro@redhat.com, atheurer@redhat.com, Juri Lelli Subject: [PATCH 5.9 RT] net: openvswitch: Fix using smp_processor_id() in preemptible code Date: Fri, 9 Oct 2020 14:47:59 +0200 Message-Id: <20201009124759.592550-1-juri.lelli@redhat.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org The following BUG has been reported (slightly edited): BUG: using smp_processor_id() in preemptible [00000000] code: handler106/3082 caller is flow_lookup.isra.15+0x2c/0xf0 [openvswitch] CPU: 46 PID: 3082 Comm: handler106 Not tainted ... #1 Hardware name: Dell Inc. PowerEdge R640/06DKY5, BIOS 2.5.4 01/13/2020 Call Trace: dump_stack+0x5c/0x80 check_preemption_disabled+0xc4/0xd0 flow_lookup.isra.15+0x2c/0xf0 [openvswitch] ovs_flow_tbl_lookup+0x3b/0x60 [openvswitch] ovs_flow_cmd_new+0x2d8/0x430 [openvswitch] ? __switch_to_asm+0x35/0x70 ? __switch_to_asm+0x41/0x70 ? __switch_to_asm+0x35/0x70 genl_family_rcv_msg+0x1d7/0x410 ? migrate_enable+0x123/0x3a0 genl_rcv_msg+0x47/0x8c ? __kmalloc_node_track_caller+0xff/0x2e0 ? genl_family_rcv_msg+0x410/0x410 netlink_rcv_skb+0x4c/0x120 genl_rcv+0x24/0x40 netlink_unicast+0x197/0x230 netlink_sendmsg+0x204/0x3d0 sock_sendmsg+0x4c/0x50 ___sys_sendmsg+0x29f/0x300 ? migrate_enable+0x123/0x3a0 ? ep_send_events_proc+0x8a/0x1f0 ? ep_scan_ready_list.constprop.23+0x237/0x260 ? rt_spin_unlock+0x23/0x40 ? ep_poll+0x1b3/0x390 ? __fget+0x72/0xa0 __sys_sendmsg+0x57/0xa0 do_syscall_64+0x87/0x1a0 entry_SYSCALL_64_after_hwframe+0x65/0xca RIP: 0033:0x7f1ed72ccb07 Code: ... RSP: 002b:00007f1ecbd9ba80 EFLAGS: 00003293 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000000007b RCX: 00007f1ed72ccb07 RDX: 0000000000000000 RSI: 00007f1ecbd9bb10 RDI: 000000000000007b RBP: 00007f1ecbd9bb10 R08: 0000000000000000 R09: 00007f1ecbd9d390 R10: 0000000019616156 R11: 0000000000003293 R12: 0000000000000000 R13: 00007f1ecbd9d338 R14: 00007f1ecbd9bfb0 R15: 00007f1ecbd9bb10 This happens because openvswitch/flow_table::flow_lookup() accesses per-cpu data while being preemptible (and migratable). Fix it by adding get/put_cpu_light(), so that, even if preempted, the task executing this code is not migrated (operation is also guarded by ovs_mutex mutex). Signed-off-by: Juri Lelli --- net/openvswitch/flow_table.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c index e2235849a57e..7df27ef7da09 100644 --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -732,11 +732,14 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl, u32 *n_cache_hit, u32 *index) { - u64 *usage_counters = this_cpu_ptr(ma->masks_usage_cntr); + u64 *usage_counters; struct sw_flow *flow; struct sw_flow_mask *mask; int i; + get_cpu_light(); + usage_counters = this_cpu_ptr(ma->masks_usage_cntr); + if (likely(*index < ma->max)) { mask = rcu_dereference_ovsl(ma->masks[*index]); if (mask) { @@ -746,6 +749,7 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl, usage_counters[*index]++; u64_stats_update_end(&ma->syncp); (*n_cache_hit)++; + put_cpu_light(); return flow; } } @@ -766,10 +770,12 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl, u64_stats_update_begin(&ma->syncp); usage_counters[*index]++; u64_stats_update_end(&ma->syncp); + put_cpu_light(); return flow; } } + put_cpu_light(); return NULL; } -- 2.26.2