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, 21 insertions, 6 deletions

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 00a96970b237..f6ff4337b424 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -111,11 +111,12 @@ static unsigned long __init init_bootmem_core(pg_data_t *pgdat,
  * might be used for boot-time allocations - or it might get added
  * to the free page pool later on.
  */
-static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
-                                        unsigned long size)
+static int __init reserve_bootmem_core(bootmem_data_t *bdata,
+                        unsigned long addr, unsigned long size, int flags)
 {
         unsigned long sidx, eidx;
         unsigned long i;
+        int ret;
 
         /*
          * round up, partially reserved pages are considered
@@ -133,7 +134,20 @@ static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long add
 #ifdef CONFIG_DEBUG_BOOTMEM
                         printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
 #endif
+                        if (flags & BOOTMEM_EXCLUSIVE) {
+                                ret = -EBUSY;
+                                goto err;
+                        }
                 }
+
+        return 0;
+
+err:
+        /* unreserve memory we accidentally reserved */
+        for (i--; i >= sidx; i--)
+                clear_bit(i, bdata->node_bootmem_map);
+
+        return ret;
 }
 
 static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
@@ -374,9 +388,9 @@ unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
 }
 
 void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
-                                 unsigned long size)
+                                 unsigned long size, int flags)
 {
-        reserve_bootmem_core(pgdat->bdata, physaddr, size);
+        reserve_bootmem_core(pgdat->bdata, physaddr, size, flags);
 }
 
 void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
@@ -398,9 +412,10 @@ unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
 }
 
 #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
-void __init reserve_bootmem(unsigned long addr, unsigned long size)
+int __init reserve_bootmem(unsigned long addr, unsigned long size,
+                            int flags)
 {
-        reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
+        return reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size, flags);
 }
 #endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */