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=-6.6 required=3.0 tests=BAYES_00,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,URIBL_BLOCKED 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 E2106C433E2 for ; Tue, 15 Sep 2020 03:24:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5B1FE208DB for ; Tue, 15 Sep 2020 03:24:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="czG0uxgt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B1FE208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BAD4A900003; Mon, 14 Sep 2020 23:24:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B5CFD8E0009; Mon, 14 Sep 2020 23:24:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A4C39900003; Mon, 14 Sep 2020 23:24:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id 8FA9A8E0009 for ; Mon, 14 Sep 2020 23:24:14 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 53835181AEF10 for ; Tue, 15 Sep 2020 03:24:14 +0000 (UTC) X-FDA: 77263852428.13.sock16_20137952710e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id 239C518140B67 for ; Tue, 15 Sep 2020 03:24:14 +0000 (UTC) X-HE-Tag: sock16_20137952710e X-Filterd-Recvd-Size: 4025 Received: from mail-pj1-f65.google.com (mail-pj1-f65.google.com [209.85.216.65]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Sep 2020 03:24:13 +0000 (UTC) Received: by mail-pj1-f65.google.com with SMTP id b17so1019024pji.1 for ; Mon, 14 Sep 2020 20:24:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=irbkPgnfVyWMQHxRCFB56no1LsWgtr4nyisml0hvN5M=; b=czG0uxgtgmPzrOOxLt4QmLQjK9z2MyB/I3cVw41+bQI4inEF/0imI47qizBZzP9IGA aBeVvkgZgvUlmGO2x8HpojXnjrb/SGdRb+rxGVk5Hi+J75XNmSIBsJm+ELSzvsps7+iM PlzLu7vx2uxw8UhKzIJFQ0gG7dMa+Lrl/iexLy9ADk/w8PHdlJk55PaKztDmo2caxnDM uuAx55TUPcqvnCij2WTA3qURpI03MY7RB1Kd4/9YOpa6Uu6mvRlmkJx4/oWQOQ08OxNN pOQiS+d6LMOl95lawfzdaUZZiaSJmAfMgbX/vN6C0ESuYiXRkUOiP/GTSg15ZiE8vcuZ 0mXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=irbkPgnfVyWMQHxRCFB56no1LsWgtr4nyisml0hvN5M=; b=d40u+M3iHLbzDYELhdkqusXS8LJOP0WDFerfEG0e+rTinHjAOwS0ouzCftgBknqlmY 3bH5LKNvh5XQngGh41XOZRqZQK2tGsKJGEjnAsLe8Q0W0vJbEQyV3y3UBF21viH7ShoA K8myERiJnnHlyg/DbC0KbgygtN57eHs5IPU8w7AkZ7RyK+XSeDrNVhUWX0Qx0RjGSWuf V126GkN/qsek+BnsrtPBwu3uYLdB6WrqrbifBkUWjjWrrTTSDwffj77KaK0255ghsa+7 6KLLTHeRigcuj4ZeUaPdJb+ZNdsV7WDCzKdOmBlcfTsEMnmwEwkjoltV8USprwz/dRtC gJLQ== X-Gm-Message-State: AOAM5326JQnISsEEIwTO5hMvqHUnew08MYgg5sBN9eJktF6zg3ozLltL LlBE21KG6Ohf/k2R+WcOJjg= X-Google-Smtp-Source: ABdhPJySSgYe8lF/6JDS960pKpGJxF72ZmNu6Ie+xgS/tQum+ZxCJr6+X0CzlaFCQ2vkb+wTaG3xAA== X-Received: by 2002:a17:90a:6e45:: with SMTP id s5mr2238591pjm.12.1600140252750; Mon, 14 Sep 2020 20:24:12 -0700 (PDT) Received: from localhost ([203.185.249.227]) by smtp.gmail.com with ESMTPSA id b20sm12442113pfb.198.2020.09.14.20.24.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2020 20:24:12 -0700 (PDT) Date: Tue, 15 Sep 2020 13:24:07 +1000 From: Nicholas Piggin Subject: Re: [PATCH v2 3/4] sparc64: remove mm_cpumask clearing to fix kthread_use_mm race To: David Miller Cc: akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, axboe@kernel.dk, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, peterz@infradead.org, sparclinux@vger.kernel.org References: <20200914045219.3736466-1-npiggin@gmail.com> <20200914045219.3736466-4-npiggin@gmail.com> <20200914.125942.5644261129883859.davem@davemloft.net> In-Reply-To: <20200914.125942.5644261129883859.davem@davemloft.net> MIME-Version: 1.0 Message-Id: <1600139445.qwycwjuwdq.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 239C518140B67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Excerpts from David Miller's message of September 15, 2020 5:59 am: > From: Nicholas Piggin > Date: Mon, 14 Sep 2020 14:52:18 +1000 >=20 > ... >> The basic fix for sparc64 is to remove its mm_cpumask clearing code. The >> optimisation could be effectively restored by sending IPIs to mm_cpumask >> members and having them remove themselves from mm_cpumask. This is more >> tricky so I leave it as an exercise for someone with a sparc64 SMP. >> powerpc has a (currently similarly broken) example. >>=20 >> Signed-off-by: Nicholas Piggin >=20 > Sad to see this optimization go away, but what can I do: >=20 > Acked-by: David S. Miller >=20 Thanks Dave, any objection if we merge this via the powerpc tree to keep the commits together? Thanks, Nick