When PAGE_SHIFT > 20, the result of "20 - PAGE_SHIFT" is negative. The
calculating here will generate an unexpected result. In addition, if
PAGE_SHIFT > 20, The memory size represented by numentries was already
integral multiple of 1MB.
Signed-off-by: Jerry <uulinux@xxxxxxxxx>
---
mm/page_alloc.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b100255..cd41797 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5745,9 +5745,11 @@ 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;
+ if (20 > PAGE_SHIFT) {
+ numentries += (1UL << (20 - PAGE_SHIFT)) - 1;
+ numentries >>= 20 - PAGE_SHIFT;
+ numentries <<= 20 - PAGE_SHIFT;
+ }
/* limit to 1 bucket per 2^scale bytes of low memory */
if (scale > PAGE_SHIFT)
--
1.8.1.5
--
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