From b3dc627cabb33fc95f93da78457770c1b2a364d2 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 20 Apr 2012 08:31:34 -0700 Subject: [PATCH] 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 Cc: stable@vger.kernel.org Reported-by: Valere Monseur Bisected-by: Joseph Freeman Tested-by: Joseph Freeman Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43098 Signed-off-by: Linus Torvalds --- mm/memblock.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/memblock.c b/mm/memblock.c index 99f285599501..a44eab3157f8 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -330,6 +330,9 @@ static int __init_memblock memblock_add_region(struct memblock_type *type, 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 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type, *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 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size) (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); }