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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 DB969C3A5A9 for ; Mon, 4 May 2020 17:04:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ADE4F206D9 for ; Mon, 4 May 2020 17:04:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729955AbgEDREz (ORCPT ); Mon, 4 May 2020 13:04:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:40134 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729910AbgEDREz (ORCPT ); Mon, 4 May 2020 13:04:55 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7BD1D206C0; Mon, 4 May 2020 17:04:53 +0000 (UTC) Date: Mon, 4 May 2020 13:04:51 -0400 From: Steven Rostedt To: Mathieu Desnoyers Cc: Joerg Roedel , linux-kernel , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Borislav Petkov , Andrew Morton , Shile Zhang , Andy Lutomirski , "Rafael J. Wysocki" , Dave Hansen , Tzvetomir Stoyanov Subject: Re: [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free_percpu() Message-ID: <20200504130451.7aef72b1@gandalf.local.home> In-Reply-To: <1533922227.82188.1588606723786.JavaMail.zimbra@efficios.com> References: <20200429054857.66e8e333@oasis.local.home> <20200430191434.GC8135@suse.de> <20200430211308.74a994dc@oasis.local.home> <1902703609.78863.1588300015661.JavaMail.zimbra@efficios.com> <20200430223919.50861011@gandalf.local.home> <20200504151236.GI8135@suse.de> <99290786.82178.1588606126392.JavaMail.zimbra@efficios.com> <20200504153135.GJ8135@suse.de> <1533922227.82188.1588606723786.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 4 May 2020 11:38:43 -0400 (EDT) Mathieu Desnoyers wrote: > ----- On May 4, 2020, at 11:31 AM, Joerg Roedel jroedel@suse.de wrote: > > > On Mon, May 04, 2020 at 11:28:46AM -0400, Mathieu Desnoyers wrote: > >> ----- On May 4, 2020, at 11:12 AM, Joerg Roedel jroedel@suse.de wrote: > >> Placing this here is inefficient. It syncs mappings for each percpu allocation. > >> I would recommend moving it right after __vmalloc() is called to allocate the > >> underlying memory chunk instead: > >> > >> static void *pcpu_mem_zalloc(size_t size, gfp_t gfp) > >> { > > > > Tried this before, actually I put it into the caller of > > pcpu_mem_zalloc(), but that didn't fix the problem for me. Stevens > > test-case still hangs the machine. > > That's unexpected. > > Did you confirm that those hangs were also caused by percpu allocations ? > > Maybe adding the vmalloc_sync_mappings() at each percpu allocation happens > to luckily sync mappings after some other vmalloc. > It doesn't surprise me because my alloc_percpu() call never gets to that path. But systemd does hit it for me earlier on. -- Steve