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 EA6FDC761A6 for ; Thu, 6 Apr 2023 14:05:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238929AbjDFOFH (ORCPT ); Thu, 6 Apr 2023 10:05:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238926AbjDFOFG (ORCPT ); Thu, 6 Apr 2023 10:05:06 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0A9F86AC; Thu, 6 Apr 2023 07:05:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=92YHTTMfDlN4SnJGHYPEf7ALbRz1gExsNSlQbfCkiJE=; b=VD9zdoH+cdV2/P8HJ83hRBLEjI JpdueSAzOmoj5lCh7T87b9I6gbGuMKT0JVGD26qs0FHKIB3yJoXQe+Y4WcX1wGtdc5Gf3D5swAlSD EXr1mZc5rPBC5shJ4xrHAyWqSOcNkw5tuIyHXQO1g47XKYVj5hQlqd5LcUwNCCAn1cGW9SS3G7uax zmp5ipQM/zPtv02Uri8vdyNZuZVVZGKIWz2E7oa+uuBEOkZHVNccAKz2SL3V1kMqabFQew4XDjGMP UDtpCwd9Y5Asm9kd3xNpC2rhBHIMzw4QpCAoQ3vLq5u1SjJpvC/3lviLAn7JaG9fKetrRHP2MOqLI rQxkw6jQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pkQDx-00AXes-0w; Thu, 06 Apr 2023 14:04:25 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 94388300194; Thu, 6 Apr 2023 16:04:23 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7CEE5212E36AC; Thu, 6 Apr 2023 16:04:23 +0200 (CEST) Date: Thu, 6 Apr 2023 16:04:23 +0200 From: Peter Zijlstra To: Marcelo Tosatti Cc: Frederic Weisbecker , Yair Podemsky , linux@armlinux.org.uk, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, will@kernel.org, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org, arnd@arndb.de, keescook@chromium.org, paulmck@kernel.org, jpoimboe@kernel.org, samitolvanen@google.com, ardb@kernel.org, juerg.haefliger@canonical.com, rmk+kernel@armlinux.org.uk, geert+renesas@glider.be, tony@atomide.com, linus.walleij@linaro.org, sebastian.reichel@collabora.com, nick.hawkins@hpe.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, vschneid@redhat.com, dhildenb@redhat.com, alougovs@redhat.com, jannh@google.com Subject: Re: [PATCH 3/3] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to CPUs in kernel mode Message-ID: <20230406140423.GA386634@hirez.programming.kicks-ass.net> References: <20230404134224.137038-1-ypodemsk@redhat.com> <20230404134224.137038-4-ypodemsk@redhat.com> <20230405195226.GB365912@hirez.programming.kicks-ass.net> <20230406132928.GM386572@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230406132928.GM386572@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Thu, Apr 06, 2023 at 03:29:28PM +0200, Peter Zijlstra wrote: > On Thu, Apr 06, 2023 at 09:38:50AM -0300, Marcelo Tosatti wrote: > > > > To actually hit this path you're doing something really dodgy. > > > > Apparently khugepaged is using the same infrastructure: > > > > $ grep tlb_remove_table khugepaged.c > > tlb_remove_table_sync_one(); > > tlb_remove_table_sync_one(); > > > > So just enabling khugepaged will hit that path. > > Urgh, WTF.. > > Let me go read that stuff :/ At the very least the one on collapse_and_free_pmd() could easily become a call_rcu() based free. I'm not sure I'm following what collapse_huge_page() does just yet.