From nobody Fri Dec 19 02:50:38 2025 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA2167F484; Mon, 29 Apr 2024 14:48:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714402095; cv=none; b=GLFVUH1Mf+frv2OSvhYjOTpGHps8b7vle5gWNkrjnz+X888jCByt2STM1n9RlricPVXLrIykKADzR5O0/7TVqQcGB+CV9mgMEGIwtTb3rQEBNNj5JSmhgrpmKJjOe3nEUml3TmttFrguP83IvNg7GiSX/u+5P96gnDuShGccIy0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714402095; c=relaxed/simple; bh=f2huQc8fgahHmmdrk7phmkAWcANNiX2OWpdSEhRxXQY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=a/SXiYWp9h7BTKgpAA7uwB7J8G+uVL1F8CSKVr9+DLvJ2LOGf4XSz5WET8d/yQ4veBK7R1PSGEjSuquiszaM8ddEzh87JEJIbEpizfKK38GtApGvt2Z1xrdyRFF0Vqlwha0tlqtf8AX5JJ1LtazAhC3gkQu8AjuwqkcfyOMkGGE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=M4lUK+ST; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="M4lUK+ST" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:Content-Type: MIME-Version:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:In-Reply-To:References; bh=a72aaBnq0xl8vUQw09satK7vYq0lUsnM7DmGvD8Qw/w=; b=M4lUK+STHg96v36YHu6yR1iWnh lFHxxPMnAQ3FOJycNnT6ILXyel8hhibbfB2qCvlsMFpj0+qNAYLWaUQatyjngBbAumkx3hNk/uiqh Nv0/alzeyMASuDFhRoWQDR0p1cFqkNNqrG5XIu8u1aHyVaW0X88Qfi59qF5HUxobM5Mk6MbrMoqX6 EWRSSY0JFLc2jYUve76OI7v2P4+2JpGFkiR5AVjxVtro4UWU9jcZNpuQv119yu0kVBEDjKG6d36ZA W/skIqqQJeSqHcMlCoKN7XvsNFS52gKuF/4h2/Ux5aR18HmIjDmN2l1+xlJcxvns83PSznzOiHoy8 0rOqKhMw==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s1SIb-0000000Cdfi-3vd5; Mon, 29 Apr 2024 14:48:10 +0000 From: "Matthew Wilcox (Oracle)" To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, "Matthew Wilcox (Oracle)" , =?UTF-8?q?=D0=9C=D0=B8=D1=85=D0=B0=D0=B8=D0=BB=20=D0=9D=D0=BE=D0=B2=D0=BE=D1=81=D0=B5=D0=BB=D0=BE=D0=B2?= , =?UTF-8?q?=D0=98=D0=BB=D1=8C=D1=84=D0=B0=D1=82=20=D0=93=D0=B0=D0=BF=D1=82=D1=80=D0=B0=D1=85=D0=BC=D0=B0=D0=BD=D0=BE=D0=B2?= , stable@vger.kernel.org, Rik van Riel , Mel Gorman , Peter Zijlstra , Ingo Molnar , Andrew Morton Subject: [PATCH] bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS Date: Mon, 29 Apr 2024 15:47:51 +0100 Message-ID: <20240429144807.3012361-1-willy@infradead.org> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable bits_per() rounds up to the next power of two when passed a power of two. This causes crashes on some machines and configurations. Reported-by: =D0=9C=D0=B8=D1=85=D0=B0=D0=B8=D0=BB =D0=9D=D0=BE=D0=B2=D0=BE= =D1=81=D0=B5=D0=BB=D0=BE=D0=B2 Tested-by: =D0=98=D0=BB=D1=8C=D1=84=D0=B0=D1=82 =D0=93=D0=B0=D0=BF=D1=82=D1= =80=D0=B0=D1=85=D0=BC=D0=B0=D0=BD=D0=BE=D0=B2 Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3347 Link: https://lore.kernel.org/all/1c978cf1-2934-4e66-e4b3-e81b04cb3571@rosa= linux.ru/ Fixes: f2d5dcb48f7b (bounds: support non-power-of-two CONFIG_NR_CPUS) Cc: stable@vger.kernel.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Rik van Riel Cc: Mel Gorman Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Andrew Morton --- kernel/bounds.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bounds.c b/kernel/bounds.c index c5a9fcd2d622..8553368ccf79 100644 --- a/kernel/bounds.c +++ b/kernel/bounds.c @@ -19,7 +19,7 @@ int main(void) DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS); DEFINE(MAX_NR_ZONES, __MAX_NR_ZONES); #ifdef CONFIG_SMP - DEFINE(NR_CPUS_BITS, bits_per(CONFIG_NR_CPUS)); + DEFINE(NR_CPUS_BITS, bits_per(CONFIG_NR_CPUS - 1)); #endif DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t)); #ifdef CONFIG_LRU_GEN --=20 2.43.0