Introduce flags for reserve_bootmem()

This patchset adds a flags variable to reserve_bootmem() and uses the
BOOTMEM_EXCLUSIVE flag in crashkernel reservation code to detect collisions
between crashkernel area and already used memory.

This patch:

Change the reserve_bootmem() function to accept a new flag BOOTMEM_EXCLUSIVE.
If that flag is set, the function returns with -EBUSY if the memory already
has been reserved in the past.  This is to avoid conflicts.

Because that code runs before SMP initialisation, there's no race condition
inside reserve_bootmem_core().

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix powerpc build]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: <linux-arch@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 8cd3a60954f0..63c62fdea521 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -27,9 +27,11 @@ void __init reserve_node_zero(pg_data_t *pgdat)
          * Note that this can only be in node 0.
          */
 #ifdef CONFIG_XIP_KERNEL
-        reserve_bootmem_node(pgdat, __pa(&__data_start), &_end - &__data_start);
+        reserve_bootmem_node(pgdat, __pa(&__data_start), &_end - &__data_start,
+                        BOOTMEM_DEFAULT);
 #else
-        reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);
+        reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext,
+                        BOOTMEM_DEFAULT);
 #endif
 
         /*
@@ -37,7 +39,8 @@ void __init reserve_node_zero(pg_data_t *pgdat)
          * some architectures which the DRAM is the exception vector to trap,
          * alloc_page breaks with error, although it is not NULL, but "0."
          */
-        reserve_bootmem_node(pgdat, CONFIG_VECTORS_BASE, PAGE_SIZE);
+        reserve_bootmem_node(pgdat, CONFIG_VECTORS_BASE, PAGE_SIZE,
+                        BOOTMEM_DEFAULT);
 }
 
 /*