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-rw-r--r--mm/sparse.c78
1 files changed, 77 insertions, 1 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index 7a3650923d9a..8ffc08990008 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -269,16 +269,92 @@ static unsigned long *__kmalloc_section_usemap(void)
}
#endif /* CONFIG_MEMORY_HOTPLUG */
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static unsigned long * __init
+sparse_early_usemap_alloc_pgdat_section(struct pglist_data *pgdat)
+{
+ unsigned long section_nr;
+
+ /*
+ * A page may contain usemaps for other sections preventing the
+ * page being freed and making a section unremovable while
+ * other sections referencing the usemap retmain active. Similarly,
+ * a pgdat can prevent a section being removed. If section A
+ * contains a pgdat and section B contains the usemap, both
+ * sections become inter-dependent. This allocates usemaps
+ * from the same section as the pgdat where possible to avoid
+ * this problem.
+ */
+ section_nr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
+ return alloc_bootmem_section(usemap_size(), section_nr);
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+ unsigned long usemap_snr, pgdat_snr;
+ static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
+ static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
+ struct pglist_data *pgdat = NODE_DATA(nid);
+ int usemap_nid;
+
+ usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
+ pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
+ if (usemap_snr == pgdat_snr)
+ return;
+
+ if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
+ /* skip redundant message */
+ return;
+
+ old_usemap_snr = usemap_snr;
+ old_pgdat_snr = pgdat_snr;
+
+ usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
+ if (usemap_nid != nid) {
+ printk(KERN_INFO
+ "node %d must be removed before remove section %ld\n",
+ nid, usemap_snr);
+ return;
+ }
+ /*
+ * There is a circular dependency.
+ * Some platforms allow un-removable section because they will just
+ * gather other removable sections for dynamic partitioning.
+ * Just notify un-removable section's number here.
+ */
+ printk(KERN_INFO "Section %ld and %ld (node %d)", usemap_snr,
+ pgdat_snr, nid);
+ printk(KERN_CONT
+ " have a circular dependency on usemap and pgdat allocations\n");
+}
+#else
+static unsigned long * __init
+sparse_early_usemap_alloc_pgdat_section(struct pglist_data *pgdat)
+{
+ return NULL;
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
static unsigned long *__init sparse_early_usemap_alloc(unsigned long pnum)
{
unsigned long *usemap;
struct mem_section *ms = __nr_to_section(pnum);
int nid = sparse_early_nid(ms);
- usemap = alloc_bootmem_node(NODE_DATA(nid), usemap_size());
+ usemap = sparse_early_usemap_alloc_pgdat_section(NODE_DATA(nid));
if (usemap)
return usemap;
+ usemap = alloc_bootmem_node(NODE_DATA(nid), usemap_size());
+ if (usemap) {
+ check_usemap_section_nr(nid, usemap);
+ return usemap;
+ }
+
/* Stupid: suppress gcc warning for SPARSEMEM && !NUMA */
nid = 0;