2016-02-04 17:31 GMT+09:00 Christian Borntraeger [off-list ref]:

On 02/04/2016 06:56 AM, Joonsoo Kim wrote:

quoted

We can disable debug_pagealloc processing even if the code is complied
with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query
whether it is enabled or not in runtime.

Signed-off-by: Joonsoo Kim <redacted>
---
 mm/slub.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 7d4da68..7b5a965 100644
--- a/mm/slub.c
+++ b/mm/slub.c

@@ -256,11 +256,12 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
 {
      void *p;

-#ifdef CONFIG_DEBUG_PAGEALLOC
-     probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p));
-#else
-     p = get_freepointer(s, object);
-#endif
+     if (debug_pagealloc_enabled()) {
+             probe_kernel_read(&p,
+                     (void **)(object + s->offset), sizeof(p));

Hmm, this might be a good case for a line longer than 80 chars....

As an alternative revert the logic and return early:


        if (!debug_pagealloc_enabled())
                return get_freepointer(s, object);
        probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p));
        return p;

Looks better!
I will fix it on next version.

Thanks.

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