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, 7 insertions, 4 deletions

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 29ae165d1749..f9f8779022a0 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -649,21 +649,24 @@ setup_memory(void)
         /*
          * Reserve memory used for lowcore/command line/kernel image.
          */
-        reserve_bootmem(0, (unsigned long)_ehead);
+        reserve_bootmem(0, (unsigned long)_ehead, BOOTMEM_DEFAULT);
         reserve_bootmem((unsigned long)_stext,
-                        PFN_PHYS(start_pfn) - (unsigned long)_stext);
+                        PFN_PHYS(start_pfn) - (unsigned long)_stext,
+                        BOOTMEM_DEFAULT);
         /*
          * Reserve the bootmem bitmap itself as well. We do this in two
          * steps (first step was init_bootmem()) because this catches
          * the (very unlikely) case of us accidentally initializing the
          * bootmem allocator with an invalid RAM area.
          */
-        reserve_bootmem(start_pfn << PAGE_SHIFT, bootmap_size);
+        reserve_bootmem(start_pfn << PAGE_SHIFT, bootmap_size,
+                        BOOTMEM_DEFAULT);
 
 #ifdef CONFIG_BLK_DEV_INITRD
         if (INITRD_START && INITRD_SIZE) {
                 if (INITRD_START + INITRD_SIZE <= memory_end) {
-                        reserve_bootmem(INITRD_START, INITRD_SIZE);
+                        reserve_bootmem(INITRD_START, INITRD_SIZE,
+                                        BOOTMEM_DEFAULT);
                         initrd_start = INITRD_START;
                         initrd_end = initrd_start + INITRD_SIZE;
                 } else {