memblock: memblock should be able to handle zero length operations
Commit 24aa07882b ("memblock, x86: Replace memblock_x86_reserve/
free_range() with generic ones") replaced x86 specific memblock
operations with the generic ones; unfortunately, it lost zero length
operation handling in the process making the kernel panic if somebody
tries to reserve zero length area.
There isn't much to be gained by being cranky to zero length operations
and panicking is almost the worst response. Drop the BUG_ON() in
memblock_reserve() and update memblock_add_region/isolate_range() so
that all zero length operations are handled as noops.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Reported-by: Valere Monseur <valere.monseur@ymail.com>
Bisected-by: Joseph Freeman <jfree143dev@gmail.com>
Tested-by: Joseph Freeman <jfree143dev@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43098
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memblock.c b/mm/memblock.c
index 99f2855..a44eab3 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -330,6 +330,9 @@
phys_addr_t end = base + memblock_cap_size(base, &size);
int i, nr_new;
+ if (!size)
+ return 0;
+
/* special case for empty array */
if (type->regions[0].size == 0) {
WARN_ON(type->cnt != 1 || type->total_size);
@@ -430,6 +433,9 @@
*start_rgn = *end_rgn = 0;
+ if (!size)
+ return 0;
+
/* we'll create at most two more regions */
while (type->cnt + 2 > type->max)
if (memblock_double_array(type) < 0)
@@ -514,7 +520,6 @@
(unsigned long long)base,
(unsigned long long)base + size,
(void *)_RET_IP_);
- BUG_ON(0 == size);
return memblock_add_region(_rgn, base, size, MAX_NUMNODES);
}