The patch titled
Subject: alloc_tag: work around clang-14 build issue with __builtin_object_size()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
alloc_tag-work-around-clang-14-issue-with-__builtin_object_size.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/alloc_tag-work-around-clang-14-issue-with-__builtin_object_size.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: alloc_tag: work around clang-14 build issue with __builtin_object_size()
Date: Sat, 1 Feb 2025 12:05:03 -0800
Additional condition in the allocation hooks causes Clang version 14
(tested on 14.0.6) to treat the allocated object size as unknown at
compile-time (__builtin_object_size(obj, 1) returns -1) even though both
branches of that condition yield the same result. Other versions of Clang
(tested with 13.0.1, 15.0.7, 16.0.6 and 17.0.6) compile the same code
without issues. Add build-time Clang version check which removes this
condition and effectively restores the unconditional tag store/restore
flow when compiled with clang-14.
Link: https://lkml.kernel.org/r/20250201200503.2532357-1-surenb@xxxxxxxxxx
Fixes: 07438779313c ("alloc_tag: avoid current->alloc_tag manipulations when profiling is disabled")
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202501310832.kiAeOt2z-lkp@xxxxxxxxx/
Cc: Bill Wendling <morbo@xxxxxxxxxx>
Cc: Justin Stitt <justinstitt@xxxxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/alloc_tag.h | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
--- a/include/linux/alloc_tag.h~alloc_tag-work-around-clang-14-issue-with-__builtin_object_size
+++ a/include/linux/alloc_tag.h
@@ -222,10 +222,23 @@ static inline void alloc_tag_sub(union c
#endif /* CONFIG_MEM_ALLOC_PROFILING */
+/* See https://lore.kernel.org/all/202501310832.kiAeOt2z-lkp@xxxxxxxxx/ */
+#if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION >= 140000 && CONFIG_CLANG_VERSION < 150000
+static inline bool store_current_tag(void)
+{
+ return true;
+}
+#else
+static inline bool store_current_tag(void)
+{
+ return mem_alloc_profiling_enabled();
+}
+#endif
+
#define alloc_hooks_tag(_tag, _do_alloc) \
({ \
typeof(_do_alloc) _res; \
- if (mem_alloc_profiling_enabled()) { \
+ if (store_current_tag()) { \
struct alloc_tag * __maybe_unused _old; \
_old = alloc_tag_save(_tag); \
_res = _do_alloc; \
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
alloc_tag-work-around-clang-14-issue-with-__builtin_object_size.patch
mm-avoid-extra-mem_alloc_profiling_enabled-checks.patch
alloc_tag-uninline-code-gated-by-mem_alloc_profiling_key-in-slab-allocator.patch
alloc_tag-uninline-code-gated-by-mem_alloc_profiling_key-in-page-allocator.patch
