The slab aliasing/merging by default transition went unnoticed (at least to the DM subsystem). Add a new SLAB_NO_MERGE flag that allows individual slabs to be created without slab merging. This beats forcing all slabs to be created in this fashion by specifying sl[au]b_nomerge on the kernel commandline. DM has historically taken care to have separate named slabs that each devices' mempool_t are backed by. These separate slabs are useful -- even if only to aid inspection of DM's memory use (via /proc/slabinfo) on production systems. I stumbled onto slab merging as a side-effect of a leak in dm-cache being attributed to 'kmalloc-96' rather than the expected 'dm_bio_prison_cell' named slab. Moving forward DM will disable slab merging for all of DM's slabs by using SLAB_NO_MERGE. Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- include/linux/slab.h | 2 ++ mm/slab.h | 2 +- mm/slab_common.c | 2 +- 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index a99f0e5..d007407 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -87,6 +87,8 @@ # define SLAB_FAILSLAB 0x00000000UL #endif +#define SLAB_NO_MERGE 0x04000000UL /* Do not merge with existing slab */ + /* The following flags affect the page allocator grouping pages by mobility */ #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */ #define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are short-lived */ diff --git a/mm/slab.h b/mm/slab.h index 8da63e4..35eb6f4 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -115,7 +115,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size, /* Legal flag mask for kmem_cache_create(), for various configurations */ #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \ - SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS ) + SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS | SLAB_NO_MERGE) #if defined(CONFIG_DEBUG_SLAB) #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER) diff --git a/mm/slab_common.c b/mm/slab_common.c index 8683110..3a5a8ed 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -35,7 +35,7 @@ struct kmem_cache *kmem_cache; */ #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \ - SLAB_FAILSLAB) + SLAB_FAILSLAB | SLAB_NO_MERGE) #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | SLAB_NOTRACK) -- 2.3.2 (Apple Git-55) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
