[PATCH] fix in __alloc_bootmem_core() when there is no free page in first node's...

Hitting BUG_ON() in __alloc_bootmem_core() when there is no free page
available in the first node's memory.  For the case of kdump on PPC64
(Power 4 machine), the captured kernel is used two memory regions - memory
for TCE tables (tce-base and tce-size at top of RAM and reserved) and
captured kernel memory region (crashk_base and crashk_size).  Since we
reserve the memory for the first node, we should be returning from
__alloc_bootmem_core() to search for the next node (pg_dat).

Currently, find_next_zero_bit() is returning the n^th bit (eidx) when there
is no free page.  Then, test_bit() is failed since we set 0xff only for the
actual size initially (init_bootmem_core()) even though rounded up to one
page for bdata->node_bootmem_map.  We are hitting the BUG_ON after failing
to enter second "for" loop.

Signed-off-by: Haren Myneni <haren@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/bootmem.c b/mm/bootmem.c
index e8c5671..16b9465 100644 (file)
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -204,6 +204,8 @@ restart_scan:
                unsigned long j;
                i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
                i = ALIGN(i, incr);
+               if (i >= eidx)
+                       break;
                if (test_bit(i, bdata->node_bootmem_map))
                        continue;
                for (j = i + 1; j < i + areasize; ++j) {