linux-kernel - Re: [PATCH 1/7] mm/sparse.c: Introduce new function fill_subsection

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Message-ID: <20200209230556.GA7326@richard>
Date:   Mon, 10 Feb 2020 07:05:56 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, dan.j.williams@...el.com,
        richardw.yang@...ux.intel.com, david@...hat.com
Subject: Re: [PATCH 1/7] mm/sparse.c: Introduce new function
 fill_subsection_map()

On Sun, Feb 09, 2020 at 06:48:20PM +0800, Baoquan He wrote:
>Wrap the codes filling subsection map in section_activate() into
>fill_subsection_map(), this makes section_activate() cleaner and
>easier to follow.
>

This looks a preparation for #ifdef the code for VMEMMAP, then why not take
the usage handling into this function too?

>Signed-off-by: Baoquan He <bhe@...hat.com>
>---
> mm/sparse.c | 45 ++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 34 insertions(+), 11 deletions(-)
>
>diff --git a/mm/sparse.c b/mm/sparse.c
>index c184b69460b7..9ad741ccbeb6 100644
>--- a/mm/sparse.c
>+++ b/mm/sparse.c
>@@ -788,24 +788,28 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> 		depopulate_section_memmap(pfn, nr_pages, altmap);
> }
> 
>-static struct page * __meminit section_activate(int nid, unsigned long pfn,
>-		unsigned long nr_pages, struct vmem_altmap *altmap)
>+/**
>+ * fill_subsection_map - fill subsection map of a memory region
>+ * @pfn - start pfn of the memory range
>+ * @nr_pages - number of pfns to add in the region
>+ *
>+ * This clears the related subsection map inside one section, and only

s/clears/fills/ ?

>+ * intended for hotplug.
>+ *
>+ * Return:
>+ * * 0		- On success.
>+ * * -EINVAL	- Invalid memory region.
>+ * * -EEXIST	- Subsection map has been set.
>+ */
>+static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
> {
>-	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> 	struct mem_section *ms = __pfn_to_section(pfn);
>-	struct mem_section_usage *usage = NULL;
>+	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> 	unsigned long *subsection_map;
>-	struct page *memmap;
> 	int rc = 0;
> 
> 	subsection_mask_set(map, pfn, nr_pages);
> 
>-	if (!ms->usage) {
>-		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
>-		if (!usage)
>-			return ERR_PTR(-ENOMEM);
>-		ms->usage = usage;
>-	}
> 	subsection_map = &ms->usage->subsection_map[0];
> 
> 	if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
>@@ -816,6 +820,25 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn,
> 		bitmap_or(subsection_map, map, subsection_map,
> 				SUBSECTIONS_PER_SECTION);
> 
>+	return rc;
>+}
>+
>+static struct page * __meminit section_activate(int nid, unsigned long pfn,
>+		unsigned long nr_pages, struct vmem_altmap *altmap)
>+{
>+	struct mem_section *ms = __pfn_to_section(pfn);
>+	struct mem_section_usage *usage = NULL;
>+	struct page *memmap;
>+	int rc = 0;
>+
>+	if (!ms->usage) {
>+		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
>+		if (!usage)
>+			return ERR_PTR(-ENOMEM);
>+		ms->usage = usage;
>+	}
>+
>+	rc = fill_subsection_map(pfn, nr_pages);
> 	if (rc) {
> 		if (usage)
> 			ms->usage = NULL;
>-- 
>2.17.2

-- 
Wei Yang
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