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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 590FDC5ACAE for ; Thu, 12 Sep 2019 00:44:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1C31C20872 for ; Thu, 12 Sep 2019 00:44:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="1YIRu7OB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C31C20872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A91D86B000A; Wed, 11 Sep 2019 20:44:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A1B296B0275; Wed, 11 Sep 2019 20:44:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E7DD6B027C; Wed, 11 Sep 2019 20:44:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0205.hostedemail.com [216.40.44.205]) by kanga.kvack.org (Postfix) with ESMTP id 6676A6B000A for ; Wed, 11 Sep 2019 20:44:03 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id DC8C78786 for ; Thu, 12 Sep 2019 00:44:02 +0000 (UTC) X-FDA: 75924421524.17.way20_629d485f0456 X-HE-Tag: way20_629d485f0456 X-Filterd-Recvd-Size: 4050 Received: from mail-ed1-f67.google.com (mail-ed1-f67.google.com [209.85.208.67]) by imf32.hostedemail.com (Postfix) with ESMTP for ; Thu, 12 Sep 2019 00:44:02 +0000 (UTC) Received: by mail-ed1-f67.google.com with SMTP id c20so13345487eds.1 for ; Wed, 11 Sep 2019 17:44:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=6StUCxf+BWs9paiGrgjzm2Rs3EDZa4/BKSwVoScmogM=; b=1YIRu7OBWjHb8fUC4OZsQnAZgF+XMXsYulmcYNiwsD9u1wQ8+Utdc1dw+m66iuQdix v5p81DWC0EjIhrdOnyRFKeqr5rM/g3udJ6VSr1MasKrLYYkh3Z4RzAF3qYUxsmA2Gnlc N4GHSmsEAARs3WKCX7kEct9w976BVLZXa6PkGWm4NZFKsMo7VyjuhEJCNBOWW5jc9KEJ vHFzHJznDAECzPgjTfQ8E23aVgbLlyG1AbpmrBx34xi0WwzzawqOkcfkQm0jqtr3FedN vUFDJiEZh58lxtic/ZjYeSEGnfQv/9tSJqml56+sMByvXjeASfUxcLOWfM6EzLF6sg0n 6o8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=6StUCxf+BWs9paiGrgjzm2Rs3EDZa4/BKSwVoScmogM=; b=cbMkYTUoXCHTSbLKfKhp2F5NysdLfoE4tcfLBlI/er8JNHo0TTGDOn0L7ZLtc6pELv NQusaK4+FWLBLA8kEVjYplJEIIpiVf7MmcNpgPgCrzk3PQCLWj9cHWtn4r0sXjv5Gco3 eqIjBPsJt6jYMULfhqPYFmlWbxal8rjj7HqiIoJ5gdJA8GTiIMmay3mVUI3Xiw9x5MZk hIAxPx8XeHqI9t6/4oWmJGK4w5th3QVdjrMPJeu+imGT0KoqebdtnDfAb8v9e7M/Sh0F AXVsxrO/tGxAL8odPV0uSh7WCFeIADw81g4ahBOsixPc7yJwWbgvB1qvd7OMk1FEuSiu PWSA== X-Gm-Message-State: APjAAAX1BAJspRvKqGnsMahQtfsCf6lm3I3rKXS5KOVJV4M2yjfZH3wL 44Kt7fkkAscHk3sUSrFYHOOGLA== X-Google-Smtp-Source: APXvYqzi7ktkOl27RjHC7fqkd1PP4Q4XGWiLksyI41yH4eDgMgZtb4qs2+CSjrzffnaM6EtMV1Zp4Q== X-Received: by 2002:a17:906:d922:: with SMTP id rn2mr31668293ejb.169.1568249041020; Wed, 11 Sep 2019 17:44:01 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id b36sm4490966edc.53.2019.09.11.17.44.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Sep 2019 17:44:00 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 58DAF101601; Thu, 12 Sep 2019 03:44:01 +0300 (+03) Date: Thu, 12 Sep 2019 03:44:01 +0300 From: "Kirill A. Shutemov" To: Yu Zhao Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Tetsuo Handa , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] mm: avoid slub allocation while holding list_lock Message-ID: <20190912004401.jdemtajrspetk3fh@box> References: <20190911071331.770ecddff6a085330bf2b5f2@linux-foundation.org> <20190912002929.78873-1-yuzhao@google.com> <20190912002929.78873-2-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190912002929.78873-2-yuzhao@google.com> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Sep 11, 2019 at 06:29:28PM -0600, Yu Zhao wrote: > If we are already under list_lock, don't call kmalloc(). Otherwise we > will run into deadlock because kmalloc() also tries to grab the same > lock. > > Instead, statically allocate bitmap in struct kmem_cache_node. Given > currently page->objects has 15 bits, we bloat the per-node struct by > 4K. So we waste some memory but only do so when slub debug is on. Why not have single page total protected by a lock? Listing object from two pages at the same time doesn't make sense anyway. Cuncurent validating is not something sane to do. -- Kirill A. Shutemov