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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 C620BC46475 for ; Thu, 25 Oct 2018 14:00:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7ADAE2075D for ; Thu, 25 Oct 2018 14:00:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7ADAE2075D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727527AbeJYWdD (ORCPT ); Thu, 25 Oct 2018 18:33:03 -0400 Received: from mga01.intel.com ([192.55.52.88]:52396 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727363AbeJYWdD (ORCPT ); Thu, 25 Oct 2018 18:33:03 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Oct 2018 07:00:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,424,1534834800"; d="scan'208";a="103224003" Received: from linux.intel.com ([10.54.29.200]) by orsmga002.jf.intel.com with ESMTP; 25 Oct 2018 07:00:10 -0700 Received: from [10.251.10.119] (kliang2-mobl1.ccr.corp.intel.com [10.251.10.119]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by linux.intel.com (Postfix) with ESMTPS id 1E0FD580496; Thu, 25 Oct 2018 07:00:09 -0700 (PDT) Subject: Re: [PATCH 1/2] perf: Add munmap callback To: Peter Zijlstra Cc: tglx@linutronix.de, mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org, bp@alien8.de, ak@linux.intel.com, eranian@google.com References: <20181024151116.30935-1-kan.liang@linux.intel.com> <20181025002943.GT3109@worktop.c.hoisthospitality.com> From: "Liang, Kan" Message-ID: <0083c5c2-8a53-3aca-543b-16bd764e31ab@linux.intel.com> Date: Thu, 25 Oct 2018 10:00:07 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181025002943.GT3109@worktop.c.hoisthospitality.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/24/2018 8:29 PM, Peter Zijlstra wrote: > On Wed, Oct 24, 2018 at 08:11:15AM -0700, kan.liang@linux.intel.com wrote: >> +void perf_event_munmap(void) >> +{ >> + struct perf_cpu_context *cpuctx; >> + unsigned long flags; >> + struct pmu *pmu; >> + >> + local_irq_save(flags); > > It is impossible to get here with IRQs already disabled. I don't think so. Based on my test, IRQs are still enabled here. I once observed dead lock with my stress test. So I have to explicitly disable the IRQs here. > >> + list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) { >> + pmu = cpuctx->ctx.pmu; >> + >> + if (!pmu->munmap) >> + continue; >> + >> + perf_ctx_lock(cpuctx, cpuctx->task_ctx); >> + perf_pmu_disable(pmu); >> + >> + pmu->munmap(); >> + >> + perf_pmu_enable(pmu); >> + >> + perf_ctx_unlock(cpuctx, cpuctx->task_ctx); >> + } >> + local_irq_restore(flags); >> +} >> + >> static void perf_event_switch(struct task_struct *task, >> struct task_struct *next_prev, bool sched_in); >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 5f2b2b184c60..61978ad8c480 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -2777,6 +2777,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, >> /* >> * Remove the vma's, and unmap the actual pages >> */ >> + perf_event_munmap(); > > I think that if you add the munmap hook, you should do it right and at > least do it such that we can solve the other munmap problem. > Is this patch you mentioned? https://lkml.org/lkml/2017/1/27/452 I will take a look and find a right place for both problems. Thanks, Kan >> detach_vmas_to_be_unmapped(mm, vma, prev, end); >> unmap_region(mm, vma, prev, start, end); >> >> -- >> 2.17.1 >>