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 mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFEDFCD4F3D for ; Wed, 20 May 2026 17:07:45 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id D46DA4042F; Wed, 20 May 2026 19:07:44 +0200 (CEST) Received: from mail-yw1-f181.google.com (mail-yw1-f181.google.com [209.85.128.181]) by mails.dpdk.org (Postfix) with ESMTP id F031B400EF for ; Wed, 20 May 2026 19:07:42 +0200 (CEST) Received: by mail-yw1-f181.google.com with SMTP id 00721157ae682-7cfc382d896so17291837b3.3 for ; Wed, 20 May 2026 10:07:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20251104.gappssmtp.com; s=20251104; t=1779296862; x=1779901662; darn=dpdk.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=zMxhDWxbMs01OYNeVfx9EdLJRs/I4aD59xafYm6/WRY=; b=oZsS3CkmN9ECendjU03LA/VhQNm+eGyp9/X8SK+u5FdrYzabpZXtIdoTlZ3hc3G3sN jPdezZ3FUHN/rpBXf5SqZJl80/da2E8/KgWMYowPP5ohzhsMqx+04N+QO743GUGIqiCr Poo1b2U6VLuRaS3H0JsgASU8vefC47oEJSbDWFNIZFGAXDh3kdfDecZzjO0469Tx6mXP UIKWXL09e3tLp2yBe/pSE8l5nsh0YUbNKUoYzrjVr5SY6B0T9W8pSygmBMxOgsDqKXW2 j5UCVEfKjVtuSd2Mcs1zuW5ELZdoHzLY5Nmp+H2JpwIdK4sduEUWPxZRysT7j0EOfWDo 9Hwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779296862; x=1779901662; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=zMxhDWxbMs01OYNeVfx9EdLJRs/I4aD59xafYm6/WRY=; b=pxNV738iLOalvk1g5dSO2aL00tx5vdv22C4tzA2At+hfdORtmfQEnYTbORDC03pq9D hnr6Rj5nCMRNHfGfrI8PL81IG0J2sl01AYlVRBB7nDcCRkyU25OVL7iUyCxwMBrBQuy8 TgwefzyQRlya3rOg9VjnivFVYF4NJi8THZ9tDP5Y00+S2bS5VjF5/M8PDN8NIrnVdWX9 oojEFzZ+j7Fkn0AQzfiHZ7jF0NIAuuCpt5omZlX/QJsgJb4qbVzGB6XUpWWPhL/zh756 YqhYsVm+nrBaBRkM3tBAzeqXD+CY9NlLxOJym0N12Vg/aD3RSIi9TJFa9niCa5I5Gneu LFjg== X-Gm-Message-State: AOJu0YyTHlp1BMAA221VF8UzXvBYcSuMFvwCpiaDGgnoDkGdWkysBnHH PtkZvAin+HKRyN1LIIoos3CSxjgWPqVYLiiWPAMzeNtQ09GPE02z3lyTaPoZBua6Ln8= X-Gm-Gg: Acq92OHN0b1zNsX5ZNc0EYJR5/2kxIzv5oNzz3nfywOWO1u+379wy0il3kWO/7nehKa qnFRbIppygksy0UpBtb3uBcPvFjD6OkkpC0/umr8oV2C25Lcd8BdINs/m2fs9k8XZ8lWeyNNc/Y 7Ke9Dj+FPoVqCIqj64scvjzNjEu7UW1J9YXvFm75O3ARDLxjRcE2bcHpmTDTtYnOiUXFNd05spd y6kCsFhA8GDMuW3rJVoSEHvFxwm/r1f+tEpVbd3277LQW5NgO3y/VbM6DsI3Zi8C6HuFMAd8Uui Jv2zzhoxGcoVX3AWv8hnP6qhOKI/TJicFl3CcA8MwSMFNMuZyH0P5td9VzCvf+kbm7aTbtTyBTY e2HMKnpwoBT0JmdkLBf8tEJsah0I4vf0y9F2k0l6WdNLPan3FkQrNjQIRIJ2Bg60cTfPgTFIBxJ Mvd4mkq6UNtRq4Wejlda+dFtZipXTVNs0krOuhboJFMTTeuwPnVvIHD1zhEAFYL/ZiI1jm6p34z RU= X-Received: by 2002:a53:c04c:0:20b0:65d:b6dd:69f3 with SMTP id 956f58d0204a3-65e227f6c40mr20082168d50.36.1779296862120; Wed, 20 May 2026 10:07:42 -0700 (PDT) Received: from phoenix.local (204-195-96-226.wavecable.com. [204.195.96.226]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-65e0dbd101asm9477962d50.19.2026.05.20.10.07.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2026 10:07:41 -0700 (PDT) Date: Wed, 20 May 2026 10:07:38 -0700 From: Stephen Hemminger To: Michal Sieron Cc: dev@dpdk.org Subject: Re: [PATCH] linux/mem: atomically prefault hugepages in alloc_seg Message-ID: <20260520100738.7042b965@phoenix.local> In-Reply-To: <20260520125756.530808-1-michal.sieron@nokia.com> References: <20260520125756.530808-1-michal.sieron@nokia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Wed, 20 May 2026 14:57:56 +0200 Michal Sieron wrote: > In rare cases, when a secondary process calls rte_eal_init() it can > cause a data race during page prefaulting in alloc_seg(). > > An atomic compare-exchange in a loop should eliminate the data race. > > Signed-off-by: Michal Sieron > --- AI had good suggestion when reviewing this. Your version is still racy (on the read side). A simple non-racy, and no loop version would be: rte_atomic_fetch_or_explicit((int *)addr, 0, rte_memory_order_relaxed);