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authorAndy Whitcroft <apw@shadowen.org>2005-06-23 00:08:00 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 09:45:05 -0700
commit29751f6991e845f7d002a6ae520bf996b38c8dcd (patch)
treef76c4c660ac4d204436f68851979343d2a9ba224 /mm
parent641c767389b19859a45e6de46d8e18cd935bdb60 (diff)
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[PATCH] sparsemem hotplug base
Make sparse's initalization be accessible at runtime. This allows sparse mappings to be created after boot in a hotplug situation. This patch is separated from the previous one just to give an indication how much of the sparse infrastructure is *just* for hotplug memory. The section_mem_map doesn't really store a pointer. It stores something that is convenient to do some math against to get a pointer. It isn't valid to just do *section_mem_map, so I don't think it should be stored as a pointer. There are a couple of things I'd like to store about a section. First of all, the fact that it is !NULL does not mean that it is present. There could be such a combination where section_mem_map *is* NULL, but the math gets you properly to a real mem_map. So, I don't think that check is safe. Since we're storing 32-bit-aligned structures, we have a few bits in the bottom of the pointer to play with. Use one bit to encode whether there's really a mem_map there, and the other one to tell whether there's a valid section there. We need to distinguish between the two because sometimes there's a gap between when a section is discovered to be present and when we can get the mem_map for it. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Bob Picco <bob.picco@hp.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c4
-rw-r--r--mm/sparse.c92
2 files changed, 74 insertions, 22 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1eb683f9b3a..7ee675ad101 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1650,8 +1650,8 @@ void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
unsigned long start_pfn)
{
struct page *page;
- int end_pfn = start_pfn + size;
- int pfn;
+ unsigned long end_pfn = start_pfn + size;
+ unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn++, page++) {
if (!early_pfn_valid(pfn))
diff --git a/mm/sparse.c b/mm/sparse.c
index f888385b9e1..b54e304df4a 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -25,7 +25,7 @@ void memory_present(int nid, unsigned long start, unsigned long end)
for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
unsigned long section = pfn_to_section_nr(pfn);
if (!mem_section[section].section_mem_map)
- mem_section[section].section_mem_map = (void *) -1;
+ mem_section[section].section_mem_map = SECTION_MARKED_PRESENT;
}
}
@@ -51,6 +51,56 @@ unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
}
/*
+ * Subtle, we encode the real pfn into the mem_map such that
+ * the identity pfn - section_mem_map will return the actual
+ * physical page frame number.
+ */
+static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
+{
+ return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+}
+
+/*
+ * We need this if we ever free the mem_maps. While not implemented yet,
+ * this function is included for parity with its sibling.
+ */
+static __attribute((unused))
+struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
+{
+ return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
+}
+
+static int sparse_init_one_section(struct mem_section *ms,
+ unsigned long pnum, struct page *mem_map)
+{
+ if (!valid_section(ms))
+ return -EINVAL;
+
+ ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
+
+ return 1;
+}
+
+static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
+{
+ struct page *map;
+ int nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
+
+ map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
+ if (map)
+ return map;
+
+ map = alloc_bootmem_node(NODE_DATA(nid),
+ sizeof(struct page) * PAGES_PER_SECTION);
+ if (map)
+ return map;
+
+ printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
+ mem_section[pnum].section_mem_map = 0;
+ return NULL;
+}
+
+/*
* Allocate the accumulated non-linear sections, allocate a mem_map
* for each and record the physical to section mapping.
*/
@@ -58,28 +108,30 @@ void sparse_init(void)
{
unsigned long pnum;
struct page *map;
- int nid;
for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
- if (!mem_section[pnum].section_mem_map)
+ if (!valid_section_nr(pnum))
continue;
- nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
- map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
- if (!map)
- map = alloc_bootmem_node(NODE_DATA(nid),
- sizeof(struct page) * PAGES_PER_SECTION);
- if (!map) {
- mem_section[pnum].section_mem_map = 0;
- continue;
- }
-
- /*
- * Subtle, we encode the real pfn into the mem_map such that
- * the identity pfn - section_mem_map will return the actual
- * physical page frame number.
- */
- mem_section[pnum].section_mem_map = map -
- section_nr_to_pfn(pnum);
+ map = sparse_early_mem_map_alloc(pnum);
+ if (map)
+ sparse_init_one_section(&mem_section[pnum], pnum, map);
}
}
+
+/*
+ * returns the number of sections whose mem_maps were properly
+ * set. If this is <=0, then that means that the passed-in
+ * map was not consumed and must be freed.
+ */
+int sparse_add_one_section(unsigned long start_pfn, int nr_pages, struct page *map)
+{
+ struct mem_section *ms = __pfn_to_section(start_pfn);
+
+ if (ms->section_mem_map & SECTION_MARKED_PRESENT)
+ return -EEXIST;
+
+ ms->section_mem_map |= SECTION_MARKED_PRESENT;
+
+ return sparse_init_one_section(ms, pfn_to_section_nr(start_pfn), map);
+}