The patch titled
Subject: codetag: debug: skip objext checking when it's for objext itself
has been added to the -mm mm-unstable branch. Its filename is
codetag-debug-skip-objext-checking-when-its-for-objext-itself.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/codetag-debug-skip-objext-checking-when-its-for-objext-itself.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: codetag: debug: skip objext checking when it's for objext itself
Date: Thu, 21 Mar 2024 09:36:55 -0700
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@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alex Gaynor <alex.gaynor@xxxxxxxxx>
Cc: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Cc: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
Cc: Benno Lossin <benno.lossin@xxxxxxxxx>
Cc: "Björn Roy Baron" <bjorn3_gh@xxxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Gary Guo <gary@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Miguel Ojeda <ojeda@xxxxxxxxxx>
Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/alloc_tag.h | 26 ++++++++++++++++++++++++++
mm/slub.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
--- a/include/linux/alloc_tag.h~codetag-debug-skip-objext-checking-when-its-for-objext-itself
+++ a/include/linux/alloc_tag.h
@@ -28,6 +28,27 @@ 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 {
@@ -140,6 +161,11 @@ static inline void alloc_tag_sub(union c
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);
--- a/mm/slub.c~codetag-debug-skip-objext-checking-when-its-for-objext-itself
+++ a/mm/slub.c
@@ -1873,6 +1873,30 @@ static inline enum node_stat_item cache_
#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 sl
* 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(st
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;
}
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
mm-introduce-slabobj_ext-to-support-slab-object-extensions.patch
mm-introduce-__gfp_no_obj_ext-flag-to-selectively-prevent-slabobj_ext-creation.patch
mm-slab-introduce-slab_no_obj_ext-to-avoid-obj_ext-creation.patch
slab-objext-introduce-objext_flags-as-extension-to-page_memcg_data_flags.patch
lib-code-tagging-framework.patch
lib-code-tagging-module-support.patch
lib-prevent-module-unloading-if-memory-is-not-freed.patch
lib-add-allocation-tagging-support-for-memory-allocation-profiling.patch
lib-introduce-support-for-page-allocation-tagging.patch
lib-introduce-early-boot-parameter-to-avoid-page_ext-memory-overhead.patch
mm-percpu-increase-percpu_module_reserve-to-accommodate-allocation-tags.patch
change-alloc_pages-name-in-dma_map_ops-to-avoid-name-conflicts.patch
mm-enable-page-allocation-tagging.patch
mm-create-new-codetag-references-during-page-splitting.patch
mm-fix-non-compound-multi-order-memory-accounting-in-__free_pages.patch
mm-page_ext-enable-early_page_ext-when-config_mem_alloc_profiling_debug=y.patch
lib-add-codetag-reference-into-slabobj_ext.patch
mm-slab-add-allocation-accounting-into-slab-allocation-and-free-paths.patch
mm-slab-enable-slab-allocation-tagging-for-kmalloc-and-friends.patch
mm-percpu-enable-per-cpu-allocation-tagging.patch
lib-add-memory-allocations-report-in-show_mem.patch
codetag-debug-skip-objext-checking-when-its-for-objext-itself.patch
codetag-debug-mark-codetags-for-reserved-pages-as-empty.patch
codetag-debug-introduce-objexts_alloc_fail-to-mark-failed-slab_ext-allocations.patch
