Re: linux-next: build warnings after merge of the mm tree

[Andrew Morton]

On Mon, 1 Jul 2024 18:49:12 +1000 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> 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?