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 1E4EFC433EF for ; Mon, 13 Jun 2022 09:22:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240338AbiFMJWa (ORCPT ); Mon, 13 Jun 2022 05:22:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232021AbiFMJW3 (ORCPT ); Mon, 13 Jun 2022 05:22:29 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 18FEA1262A for ; Mon, 13 Jun 2022 02:22:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655112147; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dMsPhpNVvNr+iFjDlmObttc0WGu8hFlqVqfZpEVrzew=; b=c0k4+Qck2qqVzcDxZ/v4daban6XKrRM3uFtHW7c8WlcEGa3omEXTYettCz6pfPzNwnM53r 59O3R9luzuR1e2dNvcIzzL+jasLkfjEUaT6pUvBfs0A60feaAPRUDMfPpuQUKGLJit3/uV I2+J3GDDC88lM5406f53Ru70kPbB7+4= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-605-uN_YvowAMMizsk4hdZZm0Q-1; Mon, 13 Jun 2022 05:22:26 -0400 X-MC-Unique: uN_YvowAMMizsk4hdZZm0Q-1 Received: by mail-ej1-f71.google.com with SMTP id gr1-20020a170906e2c100b006fefea3ec0aso1547312ejb.14 for ; Mon, 13 Jun 2022 02:22:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=dMsPhpNVvNr+iFjDlmObttc0WGu8hFlqVqfZpEVrzew=; b=fXFNXk+XU85fzLz9y/7vbEoFNrDP3tkLtU/pzckJMB1YcFtebQ9BINwzFuVabZxfZQ GxMj+a2Ym2uaHQhF1QYMJufUPVOF/5oARMJgASYP9JrYwuHiqoRZwVigR9xqQXRrwG9d J/cADvQvO4h0g8E2JzVg+kEV87dAVfR6ut60GoPM2ydEJ4xToORgCRaZ+zLD3dAsR0Hd +qQO0FFnoiGatK40CIX4uVVkRv49yLhOqWHenh+wyIFCVGSs/S7ud70922WQ3MA5Rvgu r4/k3QOFkJTcwKkSrCkOpH3YozP1yDEPTGTE4wDq1K0566AShamVR6l/VlbVd25TuAYH yh+g== X-Gm-Message-State: AOAM531sQSZCyTrYOC5y75GYnM5szmIGDcmo83hisA0MoxG4dpZWkYhE /fdT5+GF+tpmZR5SbkG1IsIa2rWqp82cAthjnsSJGT83liEA3pmvx0z+tqjvU1zRlZ3gIwdfGGd j6CS2oZGbiqmE X-Received: by 2002:a05:6402:ca2:b0:433:4a31:d0ee with SMTP id cn2-20020a0564020ca200b004334a31d0eemr19030571edb.288.1655112142770; Mon, 13 Jun 2022 02:22:22 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyY/g6w7khMaqsUdYgiQRYbXm6AODDlqhoYxvYkUq+nE43RhLQtKmwLbYMypMxWhac6YIsmQQ== X-Received: by 2002:a05:6402:ca2:b0:433:4a31:d0ee with SMTP id cn2-20020a0564020ca200b004334a31d0eemr19030497edb.288.1655112141611; Mon, 13 Jun 2022 02:22:21 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id h8-20020a1709060f4800b0070a50832376sm3573051ejj.154.2022.06.13.02.22.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jun 2022 02:22:20 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 2FFBA406851; Mon, 13 Jun 2022 11:22:20 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Satya Durga Srinivasu Prabhala , bpf@vger.kernel.org Cc: Satya Durga Srinivasu Prabhala , ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, joannelkoong@gmail.com, brouer@redhat.com Subject: Re: [PATCH] bpf: fix rq lock recursion issue In-Reply-To: <20220613025244.31595-1-quic_satyap@quicinc.com> References: <20220613025244.31595-1-quic_satyap@quicinc.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Mon, 13 Jun 2022 11:22:20 +0200 Message-ID: <87r13s2a0j.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Satya Durga Srinivasu Prabhala writes: > Below recursion is observed in a rare scenario where __schedule() > takes rq lock, at around same time task's affinity is being changed, > bpf function for tracing sched_switch calls migrate_enabled(), > checks for affinity change (cpus_ptr != cpus_mask) lands into > __set_cpus_allowed_ptr which tries acquire rq lock and causing the > recursion bug. So this only affects tracing programs that attach to tasks that can have their affinity changed? Or do we need to review migrate_enable() vs preempt_enable() for networking hooks as well? -Toke