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

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Date:   Mon, 10 Feb 2020 07:11:44 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     Wei Yang <richardw.yang@...ux.intel.com>
Cc:     Baoquan He <bhe@...hat.com>, 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 Mon, Feb 10, 2020 at 07:05:56AM +0800, Wei Yang wrote:
>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?
>

Oops, you are right. My mistake.

>>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
>Help you, Help me

-- 
Wei Yang
Help you, Help me