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=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 DC4C4C4360C for ; Thu, 26 Sep 2019 16:21:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1DEE217F4 for ; Thu, 26 Sep 2019 16:21:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="p3Ef7gDV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727447AbfIZQVF (ORCPT ); Thu, 26 Sep 2019 12:21:05 -0400 Received: from mail-io1-f44.google.com ([209.85.166.44]:32992 "EHLO mail-io1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbfIZQVF (ORCPT ); Thu, 26 Sep 2019 12:21:05 -0400 Received: by mail-io1-f44.google.com with SMTP id z19so8198546ior.0; Thu, 26 Sep 2019 09:21:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=QJ4hddZZaCwzQ+urngLpzSBE5Lf+YMOX+zDksoDMMVc=; b=p3Ef7gDVoD0fgo0Sf4pwFv3Q0EAo/Q1dAmBcMiTosyfrETgIyoGlcxBs5nOGrhd36p uoSNZJmj1brKW4FuwI8i+ZXe90LL3O41GZVRV4Dq7XguvehC9wzdjWaCmBtOrP1HzIDE Q/NgzMYEmrespkFCIVQdBUd3q6AzEYe6S03hwkCrYo82w/tkbgjIlGQNKxLErGWE+mn2 QKdJfMebk6r5P36VjKbhJG30kK4WJPRPZWQH7XrJ3CaZwwucebIzhTMbwWlg4fVATu8B OQhWZ+UXcFYmfFPvOZ6PEQ/ThRF75tgiKLBTw3Y9tCQMcxfeLC3jeO8LvcK3ZMoUirjb p6fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=QJ4hddZZaCwzQ+urngLpzSBE5Lf+YMOX+zDksoDMMVc=; b=ZzuRtflI96IGIW3GS6EZvCazrgjEoBgGKa/U3VMYTu8juqDS1+PWg6/5cNxZxkbHNM NSBbYzaiV8KGj6B0v9BnmjUWML5K1efHZw+QH4r1vAptbyo6Sy0vU34h3A9jmW6ErG34 loVHN2yGuLB/xpWEnf0wcZPh+k5L/rx/AQd8Y/fy5LOrGJIvh65rTbdCwc9mmVG2WCtY n8ipGOUcsag8tJDJjLEVLxe9PvxKc6EtJwGqBD4LUPX11x6EG6IGjRlUdrfeOCvgTsI9 7SB0RrK9bjpiPVfCk/BOavvaluD/f8JFkH17b0PMZt42N3yScCTd+hs6cJkRWjHwcc8e akdQ== X-Gm-Message-State: APjAAAVQkYvRtfYx9dQZZn6ce3HS775wvqkLu54ugAbtDGlarDt5ipf1 qd3ski3RcLaWLjC14L6eTjc= X-Google-Smtp-Source: APXvYqz6t1kCxh8lTNZOhE7J7L3/nqpQXJlXfCPWyk91LwCf3w3QZAZ+J/Ep52xFAx5bjyPdXi1bVQ== X-Received: by 2002:a5d:8b12:: with SMTP id k18mr3750297ion.93.1569514864037; Thu, 26 Sep 2019 09:21:04 -0700 (PDT) Received: from localhost ([184.63.162.180]) by smtp.gmail.com with ESMTPSA id t17sm1127473ioc.18.2019.09.26.09.21.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Sep 2019 09:21:03 -0700 (PDT) Date: Thu, 26 Sep 2019 09:20:56 -0700 From: John Fastabend To: Allan Zhang , daniel@iogearbox.net, songliubraving@fb.com, netdev@vger.kernel.org, bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Allan Zhang , Stanislav Fomichev , Eric Dumazet Message-ID: <5d8ce5686ef9f_34102b0cab5805c4b6@john-XPS-13-9370.notmuch> In-Reply-To: <20190925234312.94063-2-allanzhang@google.com> References: <20190925234312.94063-1-allanzhang@google.com> <20190925234312.94063-2-allanzhang@google.com> Subject: RE: [PATCH 1/1] bpf: Fix bpf_event_output re-entry issue Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Allan Zhang wrote: > BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can > be called from atomic and non-atomic contexts since we don't have > bpf_prog_active to prevent it happen. > > This patch enables 3 level of nesting to support normal, irq and nmi > context. > > We can easily reproduce the issue by running neper crr mode with 100 flows > and 10 threads from neper client side. > > Here is the whole stack dump: > > [ 515.228898] WARNING: CPU: 20 PID: 14686 at kernel/trace/bpf_trace.c:549 bpf_event_output+0x1f9/0x220 > [ 515.228903] CPU: 20 PID: 14686 Comm: tcp_crr Tainted: G W 4.15.0-smp-fixpanic #44 > [ 515.228904] Hardware name: Intel TBG,ICH10/Ikaria_QC_1b, BIOS 1.22.0 06/04/2018 > [ 515.228905] RIP: 0010:bpf_event_output+0x1f9/0x220 [...] > Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops") > > Effort: BPF > Signed-off-by: Allan Zhang > Reviewed-by: Stanislav Fomichev > Reviewed-by: Eric Dumazet > --- LGTM thanks. Acked-by: John Fastabend