Slab: head now uses bitmask for used/free nodes info instead of lists

From now, there are no auxiliary pointers stored in the free slab nodes.
This led to strange debugging problems if use-after-free happened in
slab-allocated structures, especially if the structure's first member is
a next pointer.

This also reduces the memory needed by 1 pointer per allocated object.
OTOH, we now rely on pages being aligned to their size's multiple, which
is quite common anyway.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/bitops.h b/lib/bitops.h
index a4c48a10..0beda2a3 100644
--- a/lib/bitops.h
+++ b/lib/bitops.h
@@ -28,6 +28,7 @@ u32 u32_log2(u32 v);
 static inline u32 u32_hash(u32 v) { return v * 2902958171u; }
 
 static inline u8 u32_popcount(u32 v) { return __builtin_popcount(v); }
+static inline u8 u64_popcount(u64 v) { return __builtin_popcountll(v); }
 
 static inline int u32_clz(u32 v) { return __builtin_clz(v); }
 static inline int u32_ctz(u32 v) { return __builtin_ctz(v); }