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Subject[RESEND PATCH 1/1] mm/vmalloc: fix align value calculation error
Date
From: zijun_hu <zijun_hu@htc.com>

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

Andrew Morton help to names the function get_count_order_long and place it
near its counterpart get_count_order()

Signed-off-by: zijun_hu <zijun_hu@htc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Hi Andrew,

please help to replace the following 6 patch series by this
patch to make commit logs clear kindly, this patch is resulted
from rebasing the 6 patch series into one, it maybe an alternative
for you to rebasing them manually

as we known, the 6 patch series fix the same issue together
they are applied in mmotm and linux-next tree currently, not
yet mainline

the 6 patch series are listed as follows
mm-vmalloc-fix-align-value-calculation-error.patch
mm-vmalloc-fix-align-value-calculation-error-fix.patch
mm-vmalloc-fix-align-value-calculation-error-v2.patch
mm-vmalloc-fix-align-value-calculation-error-v2-fix.patch
mm-vmalloc-fix-align-value-calculation-error-v2-fix-fix.patch
mm-vmalloc-fix-align-value-calculation-error-v2-fix-fix-fix.patch

include/linux/bitops.h | 36 ++++++++++++++++++++++++++----------
mm/vmalloc.c | 8 ++++----
2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 299e76b59fe9..a83c822c35c2 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -65,16 +65,6 @@ static inline int get_bitmask_order(unsigned int count)
return order; /* We could be slightly more clever with -1 here... */
}

-static inline int get_count_order(unsigned int count)
-{
- int order;
-
- order = fls(count) - 1;
- if (count & (count - 1))
- order++;
- return order;
-}
-
static __always_inline unsigned long hweight_long(unsigned long w)
{
return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
@@ -191,6 +181,32 @@ static inline unsigned fls_long(unsigned long l)
return fls64(l);
}

+static inline int get_count_order(unsigned int count)
+{
+ int order;
+
+ order = fls(count) - 1;
+ if (count & (count - 1))
+ order++;
+ return order;
+}
+
+/**
+ * get_count_order_long - get order after rounding @l up to power of 2
+ * @l: parameter
+ *
+ * it is same as get_count_order() but with long type parameter
+ */
+static inline int get_count_order_long(unsigned long l)
+{
+ if (l == 0UL)
+ return -1;
+ else if (l & (l - 1UL))
+ return (int)fls_long(l);
+ else
+ return (int)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 91f44e78c516..80660a0f989b 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1359,14 +1359,14 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
struct vm_struct *area;

BUG_ON(in_interrupt());
- if (flags & VM_IOREMAP)
- align = 1ul << clamp_t(int, fls_long(size),
- PAGE_SHIFT, IOREMAP_MAX_ORDER);
-
size = PAGE_ALIGN(size);
if (unlikely(!size))
return NULL;

+ if (flags & VM_IOREMAP)
+ align = 1ul << clamp_t(int, get_count_order_long(size),
+ PAGE_SHIFT, IOREMAP_MAX_ORDER);
+
area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
if (unlikely(!area))
return NULL;
--
1.9.1
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