mm/kmemleak.c: make cond_resched() rate-limiting more efficient

Commit bde5f6bc68db ("kmemleak: add scheduling point to
kmemleak_scan()") tries to rate-limit the frequency of cond_resched()
calls, but does it in a way which might incur an expensive division
operation in the inner loop.  Simplify this.

Fixes: bde5f6bc68db5 ("kmemleak: add scheduling point to kmemleak_scan()")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 3d4781756d50fef924f52c0d9cb6cb0cbddd479f..d73c14294f3a61c2385741b447aa31d203a2bc72 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1523,7 +1523,7 @@ static void kmemleak_scan(void)
                        if (page_count(page) == 0)
                                continue;
                        scan_block(page, page + 1, NULL);
-                       if (!(pfn % (MAX_SCAN_SIZE / sizeof(*page))))
+                       if (!(pfn & 63))
                                cond_resched();
                }
        }