[PATCH] x86: fix lower bound of crash kernel low reservation

From: Jiri Bohac
Date: Fri Jun 16 2017 - 12:16:07 EST

Commit 0212f9159694 (x86: Add Crash kernel low reservation)
introduced reserve_crashkernel_low. This is used to reserve
crash kernel memory either if crashkernel=size,low is given
on the command line or if the region reserved by
reserve_crashkernel is entirely above 4G.

reserve_crashkernel_low tries to find a block of low_size bytes.
But there seems to be no good reason to restrict the lower bound
of the range to low_size.

Make memblock_find_in_range search from the start of memory.

Signed-off-by: Jiri Bohac <jbohac@xxxxxxx>
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f81823695014..65622f07e633 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -503,7 +503,7 @@ static int __init reserve_crashkernel_low(void)
return 0;

- low_base = memblock_find_in_range(low_size, 1ULL << 32, low_size, CRASH_ALIGN);
+ low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
if (!low_base) {
pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
(unsigned long)(low_size >> 20));

Jiri Bohac <jbohac@xxxxxxx>
SUSE Labs, Prague, Czechia