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 7FC11C61DBD for ; Fri, 28 Aug 2026 12:41:21 +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=JsdYFNlmu3mZtC0DhffCWqMCuB12dqERlIoFUoVuPCg=; b=HZtt43orAuWxrukIf9rlUOG2eP P2l10gFKk78jBrwiVxsqyMdiwAmjHBNW+h7ZEXdEubujjMp/kdFRyATVCd4uR8pM31p8WtcgScxb/ 75G/pOmtbfHwc+fKMMUH3ke3PMvPi5KiIsKty1lQH844lMb4UO7dEJXvCoDPzXIh7KQacZ/jFExwA OfgRaddAKLEk3oc1fxRQSeoc8PGilip9KU+UhGsovzppFFhWd8bGEGHQlOs3pCjH3MJmpvejY1aZp ZcjU46GfMTvLEuG/sXohSdFbgFLp4RYsw/EfNw6AJ+Kl1d0kC2V2PKFDi81z0PWdEbU6Z5g8b0zKR uXKrLtAg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wzvtO-00000005ka3-2RVf; Fri, 28 Aug 2026 12:41:10 +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 1wzvtN-00000005kZu-0Bwr; Fri, 28 Aug 2026 12:41:09 +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=JsdYFNlmu3mZtC0DhffCWqMCuB12dqERlIoFUoVuPCg=; b=HzpcEx3Zje4gJfUb+ceU/x1FvE Zl3Mh4+eWu1HIJa93GBWDAjBGZo41IkX2S3AHDLV+ABH8Iudi6x4SUr8JFb7Xp+1f8Ta90NUfIQpx xATI1wocphSZX/9LCrdJL9vLsfbJVD4ikAX0dnigoFCt2X36M6tqukfVSkYUTSw7/RpzWURd7G2B7 ky42+wb5W0wgO3bhKN8rW0nZqed7CeNX1TYQw6coaPu0LDtCbvXRJ5cNfOXMnNwCO/uM4nFSEQZzM jAGWSRVFbt1xFQbORlb47ptVlPQUcPizFCQgguncsUiMarbI0Ol/17cCxaQrLbrIovxFgxl4kOQLa mZsBqG5g==; 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 1wzvtH-00000008FbN-2c6I; Fri, 28 Aug 2026 12:41:04 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 07F9C30030F; Fri, 28 Aug 2026 14:41:01 +0200 (CEST) Date: Fri, 28 Aug 2026 14:41:00 +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: <20260828124100.GO687043@noisy.programming.kicks-ass.net> References: <20260827232948.2520558-1-stevensd@google.com> <20260827232948.2520558-7-stevensd@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260827232948.2520558-7-stevensd@google.com> 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 Thu, Aug 27, 2026 at 04:29:44PM -0700, David Stevens wrote: > This feature does work on PREEMPT_RT, but is likely undesirable due to > the extra uncertainty. The fact that alloc_pages_nolock_noprof() cannot > be called from under the scheduler lock also makes repopulating stacks > more expensive. Aaah, so you knew it was hot garbage :-( Please don't ever post anything like this again.