From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5D95037266E for ; Tue, 18 Aug 2026 23:24:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787095472; cv=none; b=IgKdsRZeIq+jLShrJn0NOpx2T5ui21Fme7Y53xbI0yj2zcSxR1bwSnSgRzgvn2mHlzFkgRDVSg+vM7WT1ykTVroIUb+BsU+Q4Nhdf/q02hUz1M1ARpWHPWJoVF5XD1cbq4mwqXEnKhm1NNdgtoyo8zPKPIPNUHeBV4lLyvtdJTo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787095472; c=relaxed/simple; bh=98uHjCuNvCIy63kUfT5t+wov+YQCUz6Oi56z4eZbo80=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=BRFbgN0gqtqbxpfaGKqgycmlg4g/3NAza4Qftx1DVfjzmtKCaZy/MKOzpbOTMl9GhC0pRfKY4Lcd+WfSFkutRumFUv4rW6PHEks6q3Oew9ofIaz/yQ3PmyoY4ADam2pquDYa7l9xiAJPG80HWVf0JR7l2JekI3xffaz1uqupiN0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=SRT+6pzv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="SRT+6pzv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D20C1F000E9; Tue, 18 Aug 2026 23:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1787095470; bh=aIH6X1fb1/sEriLyBuiVQ+EzB6m/VSmiOnvuHrxsua4=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=SRT+6pzvcUuM9ptCo1ACCXsrdwT3tbAev1mMeJyRN1103rh5P5+6ZFZuV848WQqdC B8J2zyv+PDS8MvzNm9P7lMTPXlh590jG+ktscuQ2Eq/dGZp0GR7PCMOGZ35f0eyup0 BQ/Rz5F4OmQIiwKEMiViXHjuJjGzHBQwp1NkTgq0= Date: Tue, 18 Aug 2026 16:24:30 -0700 From: Andrew Morton To: Lance Yang Cc: 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: <20260818162430.0a51522ac9bd671cce62650f@linux-foundation.org> In-Reply-To: <20260818221858.86452-1-lance.yang@linux.dev> References: <20260818115526.654d7311366b66cd031c67e4@linux-foundation.org> <20260818221858.86452-1-lance.yang@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit 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.