From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 D5B95371880 for ; Fri, 28 Aug 2026 15:58:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787932728; cv=none; b=iLGpTqNAhgfW/HeIKsRXMROsas0iIKbH0tmvtzgjJQDkSgdUJ/+VL5oRiQscNm1q398zMXiiyfk1LvHZq/+LddSHm8BLNgN5fPRowNEpGaqOD5hyvO8NgIlUipiRIsoeZ5jdfgV6gNdV3DIkXzKDDpPCATgNNc+j8u+whqpZe2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787932728; c=relaxed/simple; bh=x5IFlUG3Gp1H70vRS982SS1fEJ7RE3Giv2Qt4O6gvhE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LR/lC3siGwrQrCXx9LuO+49E0iZ076SZGtrsZat1e7jbtJar0W4TM0G+6xBiubxa7uyPEdDMNb6vKgat8NTbR8wcsUcLi96NDWd2ryHCdoDREmOvl9Sgg4eNnhXpIjqrcrZq7/iCIdvIkairAM4DL5L9HgAYIdBvPSeGA6siYUw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=o2SzTzUs; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Eit7LjiA; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="o2SzTzUs"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Eit7LjiA" Date: Fri, 28 Aug 2026 17:58:42 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1787932724; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MjQ31cfuQKa5k82uaGT/Cyx34wNELqTN6/K1Rh0XD+c=; b=o2SzTzUsSOuV/AWS4fKiiKyn/1LhaPYC6Yfdi9fN77edZ6oncnntoZNhDlY+g5FN0uIwEw zDLTrEojOcnJRJhRQAb5HCWHd7BbTk9sIN0zPDHE7URywDDDKInIzLBonFQjkJNHVimBoL kWzGMCLwRRmRuqGEMRRmC+06LriM6fJe9MbsK+pBSojb6eX8G3SqLu20XaIhwBNbTl5OoI 9/FFI5P8JkXnl0wGKMTDSeUYaukHKz3pwoo7a0R18G6ypphqw6MC2H45rnhcZbOQ/ClAs7 vMj0j3h3AzvP+zmWK/m3B+PnqHU7/qIvx3PIK31jHYeE3+dcsciApSaUFtlioA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1787932724; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MjQ31cfuQKa5k82uaGT/Cyx34wNELqTN6/K1Rh0XD+c=; b=Eit7LjiABhdeRfzT4glURHG1RCeV2ZAjuv33J9ECHEaXD7arcRHH/58kzIbGZWU8KSPYLR Vh8qqix9q1P5ueBA== From: Sebastian Andrzej Siewior To: Peter Zijlstra Cc: David Stevens , 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 , 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: <20260828155842.kIh5T7iS@linutronix.de> References: <20260827232948.2520558-1-stevensd@google.com> <20260827232948.2520558-7-stevensd@google.com> <20260828133620._x2XfJR_@linutronix.de> <20260828135947.GU776954@noisy.programming.kicks-ass.net> <20260828142552.GN788244@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260828142552.GN788244@noisy.programming.kicks-ass.net> On 2026-08-28 16:25:52 [+0200], Peter Zijlstra wrote: > Taking faults on the task-stack is not going to work. That fault will > happen while you have locks held and IRQs disabled. Ideally, it'll > happen when you're knee deep in the allocator. > > That fault will then again call the allocator to allocator your stack > page, and... indeed. So I do have a few ideas floating around but I leave it at it. Sebastian