From: Alexei Starovoitov Since the combination of valid upper bits in slab->obj_exts with OBJEXTS_ALLOC_FAIL bit can never happen, use OBJEXTS_ALLOC_FAIL == (1ull << 0) as a magic sentinel instead of (1ull << 2) to free up bit 2. Signed-off-by: Alexei Starovoitov --- include/linux/memcontrol.h | 10 ++++++++-- mm/slub.c | 2 +- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 785173aa0739..d254c0b96d0d 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -341,17 +341,23 @@ enum page_memcg_data_flags { __NR_MEMCG_DATA_FLAGS = (1UL << 2), }; +#define __OBJEXTS_ALLOC_FAIL MEMCG_DATA_OBJEXTS #define __FIRST_OBJEXT_FLAG __NR_MEMCG_DATA_FLAGS #else /* CONFIG_MEMCG */ +#define __OBJEXTS_ALLOC_FAIL (1UL << 0) #define __FIRST_OBJEXT_FLAG (1UL << 0) #endif /* CONFIG_MEMCG */ enum objext_flags { - /* slabobj_ext vector failed to allocate */ - OBJEXTS_ALLOC_FAIL = __FIRST_OBJEXT_FLAG, + /* + * Use bit 0 with zero other bits to signal that slabobj_ext vector + * failed to allocate. The same bit 0 with valid upper bits means + * MEMCG_DATA_OBJEXTS. + */ + OBJEXTS_ALLOC_FAIL = __OBJEXTS_ALLOC_FAIL, /* the next bit after the last actual flag */ __NR_OBJEXTS_FLAGS = (__FIRST_OBJEXT_FLAG << 1), }; diff --git a/mm/slub.c b/mm/slub.c index 212161dc0f29..61841ba72120 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2051,7 +2051,7 @@ static inline void handle_failed_objexts_alloc(unsigned long obj_exts, * objects with no tag reference. Mark all references in this * vector as empty to avoid warnings later on. */ - if (obj_exts & OBJEXTS_ALLOC_FAIL) { + if (obj_exts == OBJEXTS_ALLOC_FAIL) { unsigned int i; for (i = 0; i < objects; i++) -- 2.47.3