From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by mx.groups.io with SMTP id smtpd.web10.7665.1601540427351852488 for ; Thu, 01 Oct 2020 01:20:27 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=Vj8BfNhk; spf=none, err=permanent DNS error (domain: infradead.org, ip: 90.155.50.34, mailfrom: peterz@infradead.org) 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=4xFuVy4XXtBpTUWYQ2Ea29srN5GWUr2xjmeW/GpcGh0=; b=Vj8BfNhkjnHd+qucd0Y3YZIbMr /8v6MUmL5V7lE1aYrJeIxmJdA8KP4SZcjrFn+6Fx4AKUcWJaBPTR/hT1jTSjS5RhCaz4ZHOAE0bfu HF91bOTY+bDxhOAZBt6koOVLvang6a7pZgwZa0Atj7aYvb0LKRP20hDesNO8bYgxzkDbD/9KkRED+ 1BhtIsyQ6dBpaoPGPLLGmiUK1JtXHVOCAMaqjDSIU93/Ncxuh6+Tkv8AHYSjBeBLFbuDjWqDjrtqN YsM1fahM/p3DMTrCofj4W0Zezk9RGtiPRm+JlcZAMmm3yBBb2/Z5lZ+BFeXD+J01ohCyHQ16JfHan tEm/mc9w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kNtop-0001ov-0A; Thu, 01 Oct 2020 08:20:03 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B5BA93011F0; Thu, 1 Oct 2020 10:19:58 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0E661205FF78B; Thu, 1 Oct 2020 10:19:58 +0200 (CEST) Date: Thu, 1 Oct 2020 10:19:58 +0200 From: Peter Zijlstra To: "Singh, Balbir" Cc: Thomas Gleixner , Lukas Bulwahn , Dave Hansen , Andy Lutomirski , Ingo Molnar , Borislav Petkov , "x86@kernel.org" , "H. Peter Anvin" , Nathan Chancellor , Nick Desaulniers , "linux-kernel@vger.kernel.org" , "clang-built-linux@googlegroups.com" , "kernel-janitors@vger.kernel.org" , "linux-safety@lists.elisa.tech" Subject: Re: [PATCH -next for tip:x86/pti] x86/tlb: drop unneeded local vars in enable_l1d_flush_for_task() Message-ID: <20201001081958.GO2628@hirez.programming.kicks-ass.net> References: <20200928124457.27289-1-lukas.bulwahn@gmail.com> <20200929071211.GJ2628@hirez.programming.kicks-ass.net> <20200929083709.GC2651@hirez.programming.kicks-ass.net> <87eemji887.fsf@nanos.tec.linutronix.de> <20200930170316.GB2628@hirez.programming.kicks-ass.net> <87blhni1pg.fsf@nanos.tec.linutronix.de> <20200930183552.GG2628@hirez.programming.kicks-ass.net> <87k0wbgd2s.fsf@nanos.tec.linutronix.de> <19f57cbe-ba33-17d5-440c-2765e670782f@amazon.com> MIME-Version: 1.0 In-Reply-To: <19f57cbe-ba33-17d5-440c-2765e670782f@amazon.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Your MUA is having trouble wrapping text at 78 chars. On Thu, Oct 01, 2020 at 09:49:30AM +1000, Singh, Balbir wrote: > So this is the change I am playing with, I don't like the idea of > killing the task, but it's better than silently not flushing, I guess > system administrators will learn with time not to correctly the > affinity of tasks flushing L1D. For the affinity bits, not being able > to change the affinity is better, but not being able to provide > feedback on as to why is a bit weird as well, but I wonder if there > are other cases where we might want to lock the affinity of a task for > it's lifetime. You can't really do that, hot-unplug can (and will) destroy any affinity setting, and if the task/admin wants to recover it needs to be able to re-set affinity after that.