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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 385D5C433ED for ; Mon, 19 Apr 2021 09:44:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BF89561073 for ; Mon, 19 Apr 2021 09:44:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF89561073 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5788B6B0036; Mon, 19 Apr 2021 05:44:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5294F6B006E; Mon, 19 Apr 2021 05:44:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3CAE76B0070; Mon, 19 Apr 2021 05:44:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id 1DCDB6B0036 for ; Mon, 19 Apr 2021 05:44:22 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id D854B180AD837 for ; Mon, 19 Apr 2021 09:44:21 +0000 (UTC) X-FDA: 78048631122.17.9CE9419 Received: from mail-oo1-f46.google.com (mail-oo1-f46.google.com [209.85.161.46]) by imf09.hostedemail.com (Postfix) with ESMTP id 3A62A6000124 for ; Mon, 19 Apr 2021 09:44:17 +0000 (UTC) Received: by mail-oo1-f46.google.com with SMTP id m25-20020a4abc990000b02901ed4500e31dso628717oop.1 for ; Mon, 19 Apr 2021 02:44:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=C4SsjBBBWAk9PglcpWZrcZB88JEvecexvFUi0GD5O9o=; b=Fnpl5H0etWSmKyfe2GsN2TRAI0qkylTHELE4LbYuKhWUKxlgbRGl90BJWvQjsnKB9t mqZ0xwCiCM/AibNY+58YgNmT+qEUb+m1c5yewpfpqUgjfjFt1fTU0C3R/5+29DXsmwqc TFLptvpbNkHFundGMJ79T9oLlGHKqcPMlRbcn6YeDWRNrFAgT4aTLWbNnGQKUIC/hIkU VSXQGBjkzXnmlnH3ysi6cYg1bur/hiPeIne1gG4frKdGqF6M9D14VlmFFn4oBdHiBwmh yiqeXIiIaYT8AITTAgrbXL4tFVEnT8cxMqj3fXUTjq0DMO89rfwKvoh6+k4V0iJLYdTe 7+Pg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=C4SsjBBBWAk9PglcpWZrcZB88JEvecexvFUi0GD5O9o=; b=WYDKlx2jDOT+T0sSEgxCPrGf1iMFjlFhTprtPqEmp8cFtaKQ4I9V0qFJmoiKFNgG9A aQr/XOZAQ7eLo+bHowQTrGrpOkCfrwfcErfIB7nXcVa90v5yIK0StRobIFENhIrrhLvF mChhNnWnRQiEZcRpptiImfc4WF2lNFvp04P0pH25MuSk+GbkuigOuLUuCaCUyNowtxIy TBzozGCT7x18o/y/vjStQkedA+ajvlQL+toeF4YGV3HbRnyLBQPw54DlCqePVak88qn7 wbIMFMLukvzA/upmGRWs2go0tTeMl6bIz+BqwZzVfn3wT/eHb0F+B5CdGvCnx/Qp7Q5O N+hw== X-Gm-Message-State: AOAM533kEkG/NQGYixQdymPzolNdgDesxGTc6OvchF5hpuPU8TJ4/cII 5kks/SVT8sjLwtddCghiw+bz1ZDM1NImPdrVuEFdxw== X-Google-Smtp-Source: ABdhPJx8V+fYrfsN3nTvs02sCEhF15TCAcIp6fVMcPZIvT+JjyJGqWTZfvLiVmqBDOCw+wunTkoXSQRfjng2FBECoR4= X-Received: by 2002:a4a:d29c:: with SMTP id h28mr12940962oos.14.1618825460590; Mon, 19 Apr 2021 02:44:20 -0700 (PDT) MIME-Version: 1.0 References: <20210419085027.761150-1-elver@google.com> <20210419085027.761150-2-elver@google.com> <20210419094044.311-1-hdanton@sina.com> In-Reply-To: <20210419094044.311-1-hdanton@sina.com> From: Marco Elver Date: Mon, 19 Apr 2021 11:44:09 +0200 Message-ID: Subject: Re: [PATCH 1/3] kfence: await for allocation using wait_event To: Hillf Danton Cc: Andrew Morton , Alexander Potapenko , Dmitry Vyukov , Jann Horn , Mark Rutland , LKML , Linux Memory Management List , kasan-dev Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3A62A6000124 X-Stat-Signature: xz61zkmwuagkwfn7h7yz3d4zcwtidrhw Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=mail-oo1-f46.google.com; client-ip=209.85.161.46 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618825457-252763 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000677, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 19 Apr 2021 at 11:41, Hillf Danton wrote: > > On Mon, 19 Apr 2021 10:50:25 Marco Elver wrote: > > + > > + WRITE_ONCE(kfence_timer_waiting, true); > > + smp_mb(); /* See comment in __kfence_alloc(). */ > > This is not needed given task state change in wait_event(). Yes it is. We want to avoid the unconditional irq_work in __kfence_alloc(). When the system is under load doing frequent allocations, at least in my tests this avoids the irq_work almost always. Without the irq_work you'd be correct of course. > > + wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ); > > + smp_store_release(&kfence_timer_waiting, false); /* Order after wait_event(). */ > > +