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

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Date:   Mon, 10 Feb 2020 11:25:12 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Wei Yang <richardw.yang@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, dan.j.williams@...el.com,
        david@...hat.com
Subject: Re: [PATCH 1/7] mm/sparse.c: Introduce new function
 fill_subsection_map()

On 02/10/20 at 07:05am, Wei Yang wrote:
> >-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/ ?

Good catch, thanks for your careful review.

I will wait a while to see if there's any input from other reviewers,
then update this post accordingly together.

> 
> >+ * 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
> Help you, Help me
>