pcpu_build_alloc_info() is an __init function that makes a call to cpumask_clear_cpu(). With CONFIG_GCOV_PROFILE_ALL enabled, the inline heuristics are modified and such cpumask_clear_cpu() which is marked inline doesn't get inlined. Because it works on mask in __initdata, modpost throws a section mismatch error.
Arnd sent a patch with the flatten attribute as an alternative [2]. I've added it to compiler_attributes.h. modpost complaint: WARNING: modpost: vmlinux.o(.text+0x735425): Section mismatch in reference from the function cpumask_clear_cpu() to the variable .init.data:pcpu_build_alloc_info.mask The function cpumask_clear_cpu() references the variable __initdata pcpu_build_alloc_info.mask. This is often because cpumask_clear_cpu lacks a __initdata annotation or the annotation of pcpu_build_alloc_info.mask is wrong. clang output: mm/percpu.c:2724:5: remark: cpumask_clear_cpu not inlined into pcpu_build_alloc_info because too costly to inline (cost=725, threshold=325) [-Rpass-missed=inline] [1] https://lore.kernel.org/linux-mm/[email protected]/ [2] https://lore.kernel.org/lkml/cak8p3a2zwfnexksm8k_suhhwkor17jfo3xaplxjzfpqx0eu...@mail.gmail.com/ Reported-by: kernel test robot <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Nick Desaulniers <[email protected]> Signed-off-by: Dennis Zhou <[email protected]> --- include/linux/compiler_attributes.h | 6 ++++++ mm/percpu.c | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index ea5e04e75845..c043b8d2b17b 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -210,6 +210,12 @@ # define fallthrough do {} while (0) /* fallthrough */ #endif +/* + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes + * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten + */ +# define __flatten __attribute__((flatten)) + /* * Note the missing underscores. * diff --git a/mm/percpu.c b/mm/percpu.c index 80f8f885a990..6596a0a4286e 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2663,7 +2663,7 @@ early_param("percpu_alloc", percpu_alloc_setup); * On success, pointer to the new allocation_info is returned. On * failure, ERR_PTR value is returned. */ -static struct pcpu_alloc_info * __init pcpu_build_alloc_info( +static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info( size_t reserved_size, size_t dyn_size, size_t atom_size, pcpu_fc_cpu_distance_fn_t cpu_distance_fn) -- 2.30.0.478.g8a0d178c01-goog
