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authorMel Gorman <mgorman@suse.de>2011-10-17 16:38:20 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-08-01 12:26:55 -0700
commit1126e70953638f9516b6a0b96385799c708815e4 (patch)
treeec88cddd81bc6d8df8e3172905e7d24a6ad86b7e /drivers
parent9116bc4fb2f96d4a3190932bf17088174da04401 (diff)
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mm: memory hotplug: Check if pages are correctly reserved on a per-section basis
commit 2bbcb8788311a40714b585fc11b51da6ffa2ab92 upstream. Stable note: Fixes https://bugzilla.novell.com/show_bug.cgi?id=721039 . Without the patch, memory hot-add can fail for kernel configurations that do not set CONFIG_SPARSEMEM_VMEMMAP. (Resending as I am not seeing it in -next so maybe it got lost) mm: memory hotplug: Check if pages are correctly reserved on a per-section basis It is expected that memory being brought online is PageReserved similar to what happens when the page allocator is being brought up. Memory is onlined in "memory blocks" which consist of one or more sections. Unfortunately, the code that verifies PageReserved is currently assuming that the memmap backing all these pages is virtually contiguous which is only the case when CONFIG_SPARSEMEM_VMEMMAP is set. As a result, memory hot-add is failing on those configurations with the message; kernel: section number XXX page number 256 not reserved, was it already online? This patch updates the PageReserved check to lookup struct page once per section to guarantee the correct struct page is being checked. [Check pages within sections properly: rientjes@google.com] [original patch by: nfont@linux.vnet.ibm.com] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/memory.c58
1 files changed, 40 insertions, 18 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 45d7c8f..5fb6aae 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -224,13 +224,48 @@ int memory_isolate_notify(unsigned long val, void *v)
}
/*
+ * The probe routines leave the pages reserved, just as the bootmem code does.
+ * Make sure they're still that way.
+ */
+static bool pages_correctly_reserved(unsigned long start_pfn,
+ unsigned long nr_pages)
+{
+ int i, j;
+ struct page *page;
+ unsigned long pfn = start_pfn;
+
+ /*
+ * memmap between sections is not contiguous except with
+ * SPARSEMEM_VMEMMAP. We lookup the page once per section
+ * and assume memmap is contiguous within each section
+ */
+ for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
+ if (WARN_ON_ONCE(!pfn_valid(pfn)))
+ return false;
+ page = pfn_to_page(pfn);
+
+ for (j = 0; j < PAGES_PER_SECTION; j++) {
+ if (PageReserved(page + j))
+ continue;
+
+ printk(KERN_WARNING "section number %ld page number %d "
+ "not reserved, was it already online?\n",
+ pfn_to_section_nr(pfn), j);
+
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/*
* MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
* OK to have direct references to sparsemem variables in here.
*/
static int
memory_block_action(unsigned long phys_index, unsigned long action)
{
- int i;
unsigned long start_pfn, start_paddr;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
struct page *first_page;
@@ -238,26 +273,13 @@ memory_block_action(unsigned long phys_index, unsigned long action)
first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
- /*
- * The probe routines leave the pages reserved, just
- * as the bootmem code does. Make sure they're still
- * that way.
- */
- if (action == MEM_ONLINE) {
- for (i = 0; i < nr_pages; i++) {
- if (PageReserved(first_page+i))
- continue;
-
- printk(KERN_WARNING "section number %ld page number %d "
- "not reserved, was it already online?\n",
- phys_index, i);
- return -EBUSY;
- }
- }
-
switch (action) {
case MEM_ONLINE:
start_pfn = page_to_pfn(first_page);
+
+ if (!pages_correctly_reserved(start_pfn, nr_pages))
+ return -EBUSY;
+
ret = online_pages(start_pfn, nr_pages);
break;
case MEM_OFFLINE: