From 239d6c96d86f8a42d799b9a85c09cc7f36aef3f8 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 21 Mar 2024 09:36:55 -0700 Subject: codetag: debug: skip objext checking when it's for objext itself MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit objext objects are created with __GFP_NO_OBJ_EXT flag and therefore have no corresponding objext themselves (otherwise we would get an infinite recursion). When freeing these objects their codetag will be empty and when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled this will lead to false warnings. Introduce CODETAG_EMPTY special codetag value to mark allocations which intentionally lack codetag to avoid these warnings. Set objext codetags to CODETAG_EMPTY before freeing to indicate that the codetag is expected to be empty. Link: https://lkml.kernel.org/r/20240321163705.3067592-34-surenb@google.com Signed-off-by: Suren Baghdasaryan Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Kent Overstreet Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Vlastimil Babka Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton --- include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++ mm/slub.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index d18388c0e9e1..3af5d6a5ced4 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -29,6 +29,27 @@ struct alloc_tag { struct alloc_tag_counters __percpu *counters; } __aligned(8); +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + +#define CODETAG_EMPTY ((void *)1) + +static inline bool is_codetag_empty(union codetag_ref *ref) +{ + return ref->ct == CODETAG_EMPTY; +} + +static inline void set_codetag_empty(union codetag_ref *ref) +{ + if (ref) + ref->ct = CODETAG_EMPTY; +} + +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ + +static inline bool is_codetag_empty(union codetag_ref *ref) { return false; } + +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ + #ifdef CONFIG_MEM_ALLOC_PROFILING struct codetag_bytes { @@ -151,6 +172,11 @@ static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes) if (!ref || !ref->ct) return; + if (is_codetag_empty(ref)) { + ref->ct = NULL; + return; + } + tag = ct_to_alloc_tag(ref->ct); this_cpu_sub(tag->counters->bytes, bytes); diff --git a/mm/slub.c b/mm/slub.c index 0fc891d44cff..00f461826462 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1873,6 +1873,30 @@ static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s) #ifdef CONFIG_SLAB_OBJ_EXT +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) +{ + struct slabobj_ext *slab_exts; + struct slab *obj_exts_slab; + + obj_exts_slab = virt_to_slab(obj_exts); + slab_exts = slab_obj_exts(obj_exts_slab); + if (slab_exts) { + unsigned int offs = obj_to_index(obj_exts_slab->slab_cache, + obj_exts_slab, obj_exts); + /* codetag should be NULL */ + WARN_ON(slab_exts[offs].ref.ct); + set_codetag_empty(&slab_exts[offs].ref); + } +} + +#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ + +static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {} + +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ + /* * The allocated objcg pointers array is not accounted directly. * Moreover, it should not come from DMA buffer and is not readily @@ -1913,6 +1937,7 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, * assign slabobj_exts in parallel. In this case the existing * objcg vector should be reused. */ + mark_objexts_empty(vec); kfree(vec); return 0; } @@ -1929,6 +1954,14 @@ static inline void free_slab_obj_exts(struct slab *slab) if (!obj_exts) return; + /* + * obj_exts was created with __GFP_NO_OBJ_EXT flag, therefore its + * corresponding extension will be NULL. alloc_tag_sub() will throw a + * warning if slab has extensions but the extension of an object is + * NULL, therefore replace NULL with CODETAG_EMPTY to indicate that + * the extension for obj_exts is expected to be NULL. + */ + mark_objexts_empty(obj_exts); kfree(obj_exts); slab->obj_exts = 0; } -- cgit v1.2.3