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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>
hifive-unleashed-5.1
Jerry Zhou 2013-09-11 14:20:26 -07:00 committed by Linus Torvalds
parent 3dbb95f789
commit a7e833182a
1 changed files with 4 additions and 3 deletions
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7
mm/page_alloc.c
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@ -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)