From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CA0F3179AF; Tue, 2 Jul 2024 03:14:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719890095; cv=none; b=tbJ0nJ+Nqx4Wq6WdZyQGcyjAB4+Z03ca7/ChZXndSmf4VK6d51m7wk0cd++vfCr6j7inEvs5i2TWaNrKCYr3jGctsJvnRRv8SPAsHN3KyscTD/VgfFvEWj93J4EiZ6ATdyrep2pEy8nGIQh7cYEv4fNJ1x0Fu6EFKORlWy9QtlE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719890095; c=relaxed/simple; bh=VynH34JpyMUrFX8rVBXDWM4HW084ZpTphUcMDiCukkk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=c1puqNDP8WUy6IWOECMsqJ6uacw0rc9xlqe31LUTaPUYtfVZvuSk/nOz/G8iCUyWqCh4w87YRuNhea4XfyQJQ7dSLdKAjqX2LQ2xI6M7ZgSWlZXenxvDLLiw1yp2CmmwPpkYwWsRi4uKs3pkkUB4Dl3pyVqIY5B6+F5GhK52Dgk= 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=CK/A/iNy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="CK/A/iNy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58C62C116B1; Tue, 2 Jul 2024 03:14:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1719890094; bh=VynH34JpyMUrFX8rVBXDWM4HW084ZpTphUcMDiCukkk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=CK/A/iNydY7m8Khg8bq6h3xgb1p7GwrKU/w6tPUTMoDe6uBCqPhuFWVUYZzakhtK0 uys8JQ2aCzczHLb0f7ipMWe1uLzGrRBFnk/0UrBcfd2f9uDTAylN8d2pMMPKet8dHi ZU+KUhgyw3pFDNAIe7GeZe3e83dtnXALur+oe+FE= Date: Mon, 1 Jul 2024 20:14:48 -0700 From: Andrew Morton To: Stephen Rothwell Cc: Jiaqi Yan , Linux Kernel Mailing List , Linux Next Mailing List , linux-doc@vger.kernel.org Subject: Re: linux-next: build warnings after merge of the mm tree Message-Id: <20240701201448.7878e9b35e1569bfc1f2ddbc@linux-foundation.org> In-Reply-To: <20240701184912.01f1f9ce@canb.auug.org.au> References: <20240701184912.01f1f9ce@canb.auug.org.au> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-next@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 Mon, 1 Jul 2024 18:49:12 +1000 Stephen Rothwell wrote: > Hi all, > > After merging the mm tree, today's linux-next build (htmldocs) produced > these warnings: > > Documentation/admin-guide/sysctl/vm.rst:278: ERROR: Unexpected indentation. > Documentation/admin-guide/sysctl/vm.rst:279: WARNING: Block quote ends without a blank line; unexpected unindent. > > Introduced by commit > > 2cba7831f62c ("docs: mm: add enable_soft_offline sysctl") Well that's annoying. @@ -267,6 +268,37 @@ used:: These are informational only. They do not mean that anything is wrong with your system. To disable them, echo 4 (bit 2) into drop_caches. +enable_soft_offline +=================== +Correctable memory errors are very common on servers. Soft-offline is kernel's +solution for memory pages having (excessive) corrected memory errors. + +For different types of page, soft-offline has different behaviors / costs. +- For a raw error page, soft-offline migrates the in-use page's content to + a new raw page. +- For a page that is part of a transparent hugepage, soft-offline splits the + transparent hugepage into raw pages, then migrates only the raw error page. + As a result, user is transparently backed by 1 less hugepage, impacting + memory access performance. +- For a page that is part of a HugeTLB hugepage, soft-offline first migrates + the entire HugeTLB hugepage, during which a free hugepage will be consumed + as migration target. Then the original hugepage is dissolved into raw + pages without compensation, reducing the capacity of the HugeTLB pool by 1. + + ... This seems a reasonable thing to do so there's probably some way in which to do it, but a bit of grepping failed to turn up examples in existing .rst files. Can someone please suggest?