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codetag: debug: skip objext checking when it's for objext itself
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 <surenb@google.com> Tested-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Andreas Hindborg <a.hindborg@samsung.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Gary Guo <gary@garyguo.net> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wedson Almeida Filho <wedsonaf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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2 changed files with 59 additions and 0 deletions
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@ -29,6 +29,27 @@ struct alloc_tag {
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struct alloc_tag_counters __percpu *counters;
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} __aligned(8);
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#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
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#define CODETAG_EMPTY ((void *)1)
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static inline bool is_codetag_empty(union codetag_ref *ref)
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{
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return ref->ct == CODETAG_EMPTY;
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}
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static inline void set_codetag_empty(union codetag_ref *ref)
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{
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if (ref)
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ref->ct = CODETAG_EMPTY;
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}
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#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
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static inline bool is_codetag_empty(union codetag_ref *ref) { return false; }
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#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
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#ifdef CONFIG_MEM_ALLOC_PROFILING
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struct codetag_bytes {
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@ -151,6 +172,11 @@ static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes)
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if (!ref || !ref->ct)
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return;
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if (is_codetag_empty(ref)) {
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ref->ct = NULL;
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return;
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}
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tag = ct_to_alloc_tag(ref->ct);
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this_cpu_sub(tag->counters->bytes, bytes);
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33
mm/slub.c
33
mm/slub.c
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@ -1873,6 +1873,30 @@ static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s)
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#ifdef CONFIG_SLAB_OBJ_EXT
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#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
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static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
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{
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struct slabobj_ext *slab_exts;
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struct slab *obj_exts_slab;
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obj_exts_slab = virt_to_slab(obj_exts);
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slab_exts = slab_obj_exts(obj_exts_slab);
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if (slab_exts) {
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unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
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obj_exts_slab, obj_exts);
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/* codetag should be NULL */
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WARN_ON(slab_exts[offs].ref.ct);
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set_codetag_empty(&slab_exts[offs].ref);
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}
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}
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#else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
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static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {}
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#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
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/*
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* The allocated objcg pointers array is not accounted directly.
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* Moreover, it should not come from DMA buffer and is not readily
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@ -1913,6 +1937,7 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
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* assign slabobj_exts in parallel. In this case the existing
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* objcg vector should be reused.
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*/
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mark_objexts_empty(vec);
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kfree(vec);
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return 0;
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}
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@ -1929,6 +1954,14 @@ static inline void free_slab_obj_exts(struct slab *slab)
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if (!obj_exts)
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return;
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/*
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* obj_exts was created with __GFP_NO_OBJ_EXT flag, therefore its
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* corresponding extension will be NULL. alloc_tag_sub() will throw a
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* warning if slab has extensions but the extension of an object is
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* NULL, therefore replace NULL with CODETAG_EMPTY to indicate that
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* the extension for obj_exts is expected to be NULL.
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*/
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mark_objexts_empty(obj_exts);
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kfree(obj_exts);
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slab->obj_exts = 0;
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}
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