Hi,
Le 13/09/2024 à 21:22, Matthew Wilcox a écrit :
On Fri, Sep 13, 2024 at 07:20:36PM +0000, Mina Almasry wrote:
+++ b/include/linux/page-flags.h
@@ -239,8 +239,8 @@ static inline unsigned long _compound_head(const struct page *page)
{
unsigned long head = READ_ONCE(page->compound_head);
- if (unlikely(head & 1))
- return head - 1;
+ if (unlikely(head & 1UL))
+ return head & ~1UL;
return (unsigned long)page_fixed_fake_head(page);
NAK, that pessimises compound_head().
Can you please give more details on what the difference is ?
I can't see what it pessimises. In both cases, you test if the value is
odd, when it is odd you make it even.
Christophe
