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authorJerry Zhou <uulinux@gmail.com>2013-09-11 14:20:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:57:12 -0700
commita7e833182a926ae5bc03204dbd00b0bb5539088b (patch)
tree9349bb816c8be88a13316d35f41b8e29b341b9d0 /mm/page_alloc.c
parent3dbb95f7895e378514ffefa93cc887fb1bc9df94 (diff)
mm: fix negative left shift count when PAGE_SHIFT > 20
When PAGE_SHIFT > 20, the result of "20 - PAGE_SHIFT" is negative. The previous calculating here will generate an unexpected result. In addition, if PAGE_SIZE >= 1MB, The memory size of "numentries" was already integral multiple of 1MB. Signed-off-by: Jerry Zhou <uulinux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c2b59dbda196..116bab1c2cf5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5745,9 +5745,10 @@ void *__init alloc_large_system_hash(const char *tablename,
if (!numentries) {
/* round applicable memory size up to nearest megabyte */
numentries = nr_kernel_pages;
- numentries += (1UL << (20 - PAGE_SHIFT)) - 1;
- numentries >>= 20 - PAGE_SHIFT;
- numentries <<= 20 - PAGE_SHIFT;
+
+ /* It isn't necessary when PAGE_SIZE >= 1MB */
+ if (PAGE_SHIFT < 20)
+ numentries = round_up(numentries, (1<<20)/PAGE_SIZE);
/* limit to 1 bucket per 2^scale bytes of low memory */
if (scale > PAGE_SHIFT)