From mboxrd@z Thu Jan 1 00:00:00 1970 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 BE80A18C910 for ; Mon, 28 Oct 2024 10:16:40 +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=1730110602; cv=none; b=oMd5upZiBg1u3U6soAjekaETcyMd0XHw2LZR7ap0WwBlrDylRbPvcT0cPHtGIF26By1hvTesnCgzbA1GuqkOd5CBDAdcSPWxWHWWzdx6X+Ze9toa88DqKBj4FXZhXPuy1ThtUJagvTmGEjzuzQrWLhVNpaokIOFMBPyLFJu/SUw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730110602; c=relaxed/simple; bh=pZkcm+KV+yjm9a2ASWvSYVQ57m9OBeAd5fup9Y303XE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=G7YPezNwlV3RQ+iG363Pk7cshZqiEhmj5QI3dx0R0+RoONxwuqWld5V+kJDcwpvp1Q+LQSIFsnAncEJfyn/dAPlt/BVSiuiscQjCVVnVzHZvMRXXSJI/UJYe7kbgR3GMUaRPKgyvtJ0hjCN0e2EZ6cYGsqGpDNQBT7rh0bH3vNI= 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=f56RSobF; 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="f56RSobF" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0C8KesZBo9hE0DFXc72TfXvQTFF0Y2Df9m8IM9xFT0c=; b=f56RSobFwX3qTSzjA3QUkVe1yj tLEcJb/wKjzjLRjxUbflcajLdZM8BPny4XRJlJbsMx22eQy+uEA+qpn/pYUvKdsCvOfaYCpzl76cN U2qQy2nYg+HQ/qXD6wZiRNS64Nj3deDgUt/nYzOzMBtTckKqeEHP/bHLbmLClQ3ylNxZu5ZxprxBu o0atp8Xek9+ZJ7stcQNzyLx+a0NvSvhcdPT8C04ixsZltWUj3jVqJ12UjAd2aXYSSygdsK/e3y+4+ gsIyW9feC56+KnCxb8pI/gUDkJ0z7UqpvPeYYSwWJ6Fnt8TsIczljgCE3jFrRPBktw1DjB2pQBwe3 vaz0UDqg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t5Mna-00000008FLk-16Ra; Mon, 28 Oct 2024 10:16:35 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0C7AF30083E; Mon, 28 Oct 2024 11:16:34 +0100 (CET) Date: Mon, 28 Oct 2024 11:16:33 +0100 From: Peter Zijlstra To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, =?iso-8859-1?Q?Andr=E9?= Almeida , Darren Hart , Davidlohr Bueso , Ingo Molnar , Juri Lelli , Valentin Schneider , Waiman Long Subject: Re: [RFC PATCH 2/3] futex: Add basic infrastructure for local task local hash. Message-ID: <20241028101633.GM9767@noisy.programming.kicks-ass.net> References: <20241026224306.982896-1-bigeasy@linutronix.de> <20241026224306.982896-3-bigeasy@linutronix.de> 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=us-ascii Content-Disposition: inline In-Reply-To: <20241026224306.982896-3-bigeasy@linutronix.de> On Sun, Oct 27, 2024 at 12:34:51AM +0200, Sebastian Andrzej Siewior wrote: > Introduce a task local hash map. The hashmap can be allocated via > prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_ALLOCATE, 0) Per process, per task is useless and will make things malfunction. Things missing in this patch are CLONE_THREAD / CLONE_VM, and create must be absolutely forbidden once mm_users != 1.