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| author | Jerry Zhou <uulinux@gmail.com> | 2013-09-11 14:20:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:57:12 -0700 |
| commit | a7e833182a926ae5bc03204dbd00b0bb5539088b (patch) | |
| tree | 9349bb816c8be88a13316d35f41b8e29b341b9d0 | |
| parent | 3dbb95f7895e378514ffefa93cc887fb1bc9df94 (diff) | |
| download | linux-a7e833182a926ae5bc03204dbd00b0bb5539088b.tar.bz2 | |
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>
| -rw-r--r-- | mm/page_alloc.c | 7 |
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) |