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 <[email protected]> Cc: [email protected] Reported-by: Valere Monseur <[email protected]> Bisected-by: Joseph Freeman <[email protected]> Tested-by: Joseph Freeman <[email protected]> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43098 --- This is causing early panics if anyone tries to reserve zero len area, which unfortunately isn't too uncommon depending on BIOS. The fix is fairly safe. Unsure which tree it should go through. Cc'ing Linus and Ingo. Thanks. mm/memblock.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) 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 @@ 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); } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
