vmap: add flag to allow lazy unmap to be disabled at runtime

Add a flag to force lazy_max_pages() to zero to prevent any outstanding
mapped pages.  We'll need this for Xen.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Nick Piggin <npiggin@suse.de>

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 227c2a585e4f326a4e3355fc01f34a1eb4901b03..b840fdaf438c7814cadd0b3800aa5e9e14fcd913 100644 (file)
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -7,6 +7,8 @@
 
 struct vm_area_struct;         /* vma defining user mapping in mm_types.h */
 
+extern bool vmap_lazy_unmap;
+
 /* bits in flags of vmalloc's vm_struct below */
 #define VM_IOREMAP     0x00000001      /* ioremap() and friends */
 #define VM_ALLOC       0x00000002      /* vmalloc() */

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ae007462b7f6e8c2463d83edc2d202107f996a32..7f35fe2cf9e7cbbef465fe1b985608e8c1f99d84 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -31,6 +31,7 @@
 #include <asm/tlbflush.h>
 #include <asm/shmparam.h>
 
+bool vmap_lazy_unmap __read_mostly = true;
 
 /*** Page table manipulation functions ***/
 
@@ -502,6 +503,9 @@ static unsigned long lazy_max_pages(void)
 {
        unsigned int log;
 
+       if (!vmap_lazy_unmap)
+               return 0;
+
        log = fls(num_online_cpus());
 
        return log * (32UL * 1024 * 1024 / PAGE_SIZE);