memory hotplug: fix early allocation handling

Trying to add memory via add_memory() from within an initcall function
results in

bootmem alloc of 163840 bytes failed!
Kernel panic - not syncing: Out of memory

This is caused by zone_wait_table_init() which uses system_state to decide
if it should use the bootmem allocator or not.

When initcalls are handled the system_state is still SYSTEM_BOOTING but
the bootmem allocator doesn't work anymore.  So the allocation will fail.

To fix this use slab_is_available() instead as indicator like we do it
everywhere else.

[akpm@linux-foundation.org: coding-style fix]
Reviewed-by: Andy Whitcroft <apw@shadowen.org>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7f4c66ff65b796a840086301eccf2c9c94044076..8e83f02cd2d3d0bdb7124588e11e6d2950bd67ea 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2807,7 +2807,7 @@ int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
        alloc_size = zone->wait_table_hash_nr_entries
                                        * sizeof(wait_queue_head_t);
 
-       if (system_state == SYSTEM_BOOTING) {
+       if (!slab_is_available()) {
                zone->wait_table = (wait_queue_head_t *)
                        alloc_bootmem_node(pgdat, alloc_size);
        } else {