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 25242378D6B for ; Tue, 18 Aug 2026 23:46:17 +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=1787096782; cv=none; b=eBNlS/I/qFB1Smwj6sf1RRdNVSvUbXu/bXotBYQ6YVh0++UjGeFo/JYXpKAALQY5lhcP2OTThtadeK46Ox83lYao2eQatG7R9c+aVhxwXRw3FbAERCs6/jJtd/lCyPHjKTgwNkpGjyDOXMTs8iJiKXR6ScOmrkmMc9a/EyEI8yA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787096782; c=relaxed/simple; bh=NsSlpt5oTYlGDTRhFpAYcsU9iWX6eABT22cutg7gq3Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=h/zLy0tvM6wYsoQRzzgLttINCraLuTbcmhJsS+2Zeue3C7N5ipf1xDwaZ7OfWQLoqZl8cJt35J0y3lc9qfTxOKuuD35Z4x0YAWqZtBJ1H26jJuODud9G5lLim1OC102EdvE5BHeZJDKsFb3V4zXJM0hYgmZLIBb3D9bouwlzBRU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=IOEZHV9d; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass 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="IOEZHV9d" 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=aEupeHIpt7OfU2n3KVFf/NixP6ZlUu34HUVlp84fKL8=; b=IOEZHV9dHZvSA7iWBZfSP2TaEZ /CAujOUJr9/N9i+hkSstmcRlvCofYvaKWeYpYRmcnfFVapO05dnpDrYg/YdPbPRfZDgPGqepC8snE wJjA+biMXikKvdno5NdhmPC0Q7WATxmbmksOLp8/5b/Cz8H2a1sOEY54OdToZyh5hD5q3s4ZYBzsT LCRHNfXXM+ztGo31EDztA12S4L7nCxj9/AOlmYwohWQexoqG/ZysAaasf6AIj1q12K5RgwkLa51+l X2Q0D/qFuyldYzGr0+eOC4qipuuKS33P3ERjE4m9DjJOdFpYnBta1TrBwvtoLCOtYT5lxlSP09oEp fOmuZ/rQ==; Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wwTVR-0000000Cmxv-0rwC; Tue, 18 Aug 2026 23:46:09 +0000 Date: Wed, 19 Aug 2026 00:46:09 +0100 From: Matthew Wilcox To: Andrew Morton Cc: Lance Yang , david@kernel.org, mhocko@suse.com, leon.hwang@linux.dev, linux-mm@kvack.org, muchun.song@linux.dev, osalvador@suse.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH] hugetlb: add cond_resched() to __unmap_hugepage_range() Message-ID: References: <20260818115526.654d7311366b66cd031c67e4@linux-foundation.org> <20260818221858.86452-1-lance.yang@linux.dev> <20260818162430.0a51522ac9bd671cce62650f@linux-foundation.org> 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: <20260818162430.0a51522ac9bd671cce62650f@linux-foundation.org> On Tue, Aug 18, 2026 at 04:24:30PM -0700, Andrew Morton wrote: > On Wed, 19 Aug 2026 06:18:58 +0800 Lance Yang wrote: > > > >> > > > >> > That's pretty bad behavior and we might want to fix it in earlier > > >> > kernels. Is PREEMPT_NONE effectively dead in 6.18.x and its > > >> > existing users? > > >> > > > >> > If yes, we do want to fix older kernels then we should merge this. > > >> > > > >> > > >> Okay, but that would be stable-only fixes? > > > > > >Not understanding. > > > > > >Maybe you refer to adding a patch to -stable but not to -linus? That's > > >against the -stable rules > > >(Documentation/process/stable-kernel-rules.rst). > > > > Since cond_resched() is a scheduling no-op under LAZY/FULL anyway (only > > the __might_resched() debug check remains), why not take this upstream > > with Cc: stable? > > I think so - as long as PREEPMT_NONE exists we should support it as > well as we can. If the day comes that PREEMPT_NONE is removed, then we > get to remove lots of cond_resched()s. mm/ has 200 of the things. > > > Mainline scheduling stays unchanged, and stable can pick it up for old > > PREEMPT_NONE kernels. wdyt? > > Addressing this issue in older kernels is another reason. That is not the direction that the scheduler developers wish us to take.