mm/vmalloc.c: fix align value calculation error

It causes double align requirement for __get_vm_area_node() if parameter
size is power of 2 and VM_IOREMAP is set in parameter flags, for example
size=0x10000 -> fls_long(0x10000)=17 -> align=0x20000

get_count_order_long() is implemented and used instead of fls_long() for
fixing the bug, for example
size=0x10000 -> get_count_order_long(0x10000)=16 -> align=0x10000

Link: http://lkml.kernel.org/r/fc045ecf-20fa-0722-b3ac-9a6140488fad@zoho.com
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 299e76b59fe9b0330254f608863f7237ed97c802..c18448de2c574531cb34868800b488b20228ef77 100644 (file)
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -191,6 +191,23 @@ static inline unsigned fls_long(unsigned long l)
        return fls64(l);
 }
 
+/**
+ * get_order_long - get order after rounding @l up to power of 2
+ * @l: parameter
+ *
+ * it is same as get_count_order() but long type parameter
+ * or 0 is returned if @l == 0UL
+ */
+static inline int get_order_long(unsigned long l)
+{
+       if (l == 0UL)
+               return 0;
+       else if (l & (l - 1UL))
+               return fls_long(l);
+       else
+               return fls_long(l) - 1;
+}
+
 /**
  * __ffs64 - find first set bit in a 64 bit word
  * @word: The 64 bit word

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e78c516f67ff9969f47679bcefa22eed61d..7d717f3eb2884bdaf1dc7bdbe9868a87e4255e6b 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1360,7 +1360,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
 
        BUG_ON(in_interrupt());
        if (flags & VM_IOREMAP)
-               align = 1ul << clamp_t(int, fls_long(size),
+               align = 1ul << clamp_t(int, get_order_long(size),
                                       PAGE_SHIFT, IOREMAP_MAX_ORDER);
 
        size = PAGE_ALIGN(size);