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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EF172C61DBE for ; Sat, 29 Aug 2026 08:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=eHtGfUyv+NDEIFhJ+rL3MIjkKe1E4CjtH7InBn8uMWg=; b=nur6MYuhtLObW7yiwtBq1gvTmV t52a2HW90kf2eUwqC/RAC4j6r/XlcTUM17ha4OWpniCiRTeEFLl7fcci0Zb2l56iWeLf/oHOQMRil jdKvkEZkm5RBPNUKsnnisM5npVY+fHCcVGWyf75ZfrPjfLRO1h3QgWs3murht/adG9it6zGq/rfBI PrN4mcg3Vsf79xV1tvnZccZut4mIgwfZN7VkUQDsWS7NJO/poKuqjzMbNyWeDcOjhjQRLS1rtkwDf vq6NwVGAri9YvMy9jkLNp+gXuwZ0liLl1jLVzoDUj4DjGPk1ps8/6xcffHJwYLN9hEOE64ZYXO+4t /0Ts3VXA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0Ef3-00000006rrq-38es; Sat, 29 Aug 2026 08:43:37 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0Ef3-00000006rrf-02dd; Sat, 29 Aug 2026 08:43:37 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=eHtGfUyv+NDEIFhJ+rL3MIjkKe1E4CjtH7InBn8uMWg=; b=ZvkODfUjRXxzIXS3gx3ArInBac P7e8ollFJxQa2Sca0uHxuOn78euth+7/OAAiWvXv6gEwDtQknf7cRvXWnrXRC2yeBBdca7QE2cGUH JLa79YPVenz9rxuNyOEFGhm+ccbJeNvWEB/Z9nIUAC1YCfAmY55xMmC+9uUBr3nXDppmCSjZZpwnO vlJJLLxWzK+kbzE/MwrXBaW/lg+/Mrae2Kn9aV6xeIJ9gZQMa/vniKr1+V2AjwDvjTcBspOXTbRnY 1xt11Kr2Yb71UtBujJZUKVfj22zEn/HMC9+E3dvI9A4FxgJ3Tw4qpqLo1axhRxTkOeP/iD7/GtYdA m4xg5f1g==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.2 #2 (Red Hat Linux)) id 1x0Eew-00000008le1-27hC; Sat, 29 Aug 2026 08:43:31 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 63BD7300382; Sat, 29 Aug 2026 10:43:28 +0200 (CEST) Date: Sat, 29 Aug 2026 10:43:28 +0200 From: Peter Zijlstra To: David Stevens Cc: Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Andrew Morton , Dave Chinner , Qi Zheng , Roman Gushchin , Muchun Song , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Uladzislau Rezki , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Sebastian Andrzej Siewior , Clark Williams , suleiman@google.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-rt-devel@lists.linux.dev Subject: Re: [RFC 06/10] Reclaim memory from blocked kernel stacks Message-ID: <20260829084328.GO788244@noisy.programming.kicks-ass.net> References: <20260827232948.2520558-1-stevensd@google.com> <20260827232948.2520558-7-stevensd@google.com> <20260828120408.GN687043@noisy.programming.kicks-ass.net> <20260829083929.GZ776954@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260829083929.GZ776954@noisy.programming.kicks-ass.net> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, Aug 29, 2026 at 10:39:29AM +0200, Peter Zijlstra wrote: > > The optimistic fast path for repopulate_stack() could be modified to > > try pulling from a pre-allocated pool of zero'ed pages. That would > > reduce the function to a couple of memcg_kmem_charge_page() calls and > > Afaict memcg_kmem_charge_page() ends up in a local_lock, which is a > spinlock, so that cannot be. Perhaps just don't uncharge them on reclaim, then you don't have to re-charge.