[vbabka-slab:slab/for-next 11/12] mm/slub.c:3256:14: error: call to undeclared function 'node_nr_objs'; ISO C99 and later do not support implicit function declarations

[Jianfeng Wang <jianfeng.w.wang@oracle.com>]

On 4/22/24 7:21 PM, kernel test robot wrote:
> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git slab/for-next
> head:   b6f00c4ef02065161c09fdf560e492cfbb1fec0a
> commit: 1c5610f451be71ca2f8b9c6b86ef4712aeed6437 [11/12] slub: introduce count_partial_free_approx()
> config: arm-mps2_defconfig (https://urldefense.com/v3/__https://download.01.org/0day-ci/archive/20240423/202404231035.P6HbfrHW-lkp@intel.com/config__;!!ACWV5N9M2RV99hQ!OME34mL_ADYQENhnXxNwsh7RcI01QQqhK9FJsBEMMQaQVDaJM3wclQX94a6zSFnvxan0Qx-_wzC34V4$ )
> compiler: clang version 19.0.0git (https://urldefense.com/v3/__https://github.com/llvm/llvm-project__;!!ACWV5N9M2RV99hQ!OME34mL_ADYQENhnXxNwsh7RcI01QQqhK9FJsBEMMQaQVDaJM3wclQX94a6zSFnvxan0Qx-_bxtcvFE$  5ef5eb66fb428aaf61fb51b709f065c069c11242)
> reproduce (this is a W=1 build): (https://urldefense.com/v3/__https://download.01.org/0day-ci/archive/20240423/202404231035.P6HbfrHW-lkp@intel.com/reproduce__;!!ACWV5N9M2RV99hQ!OME34mL_ADYQENhnXxNwsh7RcI01QQqhK9FJsBEMMQaQVDaJM3wclQX94a6zSFnvxan0Qx-_K2OZqIs$ )
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-kbuild-all/202404231035.P6HbfrHW-lkp@intel.com/__;!!ACWV5N9M2RV99hQ!OME34mL_ADYQENhnXxNwsh7RcI01QQqhK9FJsBEMMQaQVDaJM3wclQX94a6zSFnvxan0Qx-_gVX_avo$ 
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from mm/slub.c:13:
>    In file included from include/linux/mm.h:2208:
>    include/linux/vmstat.h:522:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
>      522 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
>          |                               ~~~~~~~~~~~ ^ ~~~
>>> mm/slub.c:3256:14: error: call to undeclared function 'node_nr_objs'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
>     3256 |                 x = min(x, node_nr_objs(n));
>          |                            ^
>    mm/slub.c:3256:14: note: did you mean 'node_nr_slabs'?

I'm sorry that I didn't catch this when I submitted.
For the v3 patchset, I placed this new function under
"#if defined(CONFIG_SLUB_DEBUG) || defined(SLAB_SUPPORTS_SYSFS)".
However, this causes problems: (1) node_nr_objs() is defined under
CONFIG_SLUB_DEBUG; (2) count_partial_free_approx() is only used under
CONFIG_SLUB_DEBUG. So, if CONFIG_SLUB_DEBUG is not set and
SLAB_SUPPORTS_SYSFS is set, the compilation will fail.

I've submitted a v4 that moves count_partial_free_approx() under
CONFIG_SLUB_DEBUG only, as it is not used in sysfs. Only the first patch is modified.

Here is the link:
https://lore.kernel.org/linux-mm/20240423045554.15045-1-jianfeng.w.wang@oracle.com/T/#t

>    mm/slub.c:1862:29: note: 'node_nr_slabs' declared here
>     1862 | static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
>          |                             ^
>>> mm/slub.c:3256:7: error: static assertion failed due to requirement '__builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((unsigned long)(-1)) < (unsigned long)1)) * 0L)) : (int *)8))), (((unsigned long)(-1)) < (unsigned long)1), 0) == __builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((int)(-1)) < (int)1)) * 0L)) : (int *)8))), (((int)(-1)) < (int)1), 0) || __builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((unsigned long)(-1)) < (unsigned long)1)) * 0L)) : (int *)8))), (((unsigned long)(-1)) < (unsigned long)1), 0) == __builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((int)(-1)) < (int)1)) * 0L)) : (int *)8))), (((int)(-1)) < (int)1), 0) || (__builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)(x) * 0L)) : (int *)8))) && __builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((unsigned long)(-1)) < (unsigned long)1)) * 0L)) : (int *)8))), (((unsigned long)(-1)) < (unsigned long)1), 0), x, -1) >= 0) || (__builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)(node_nr_objs(n)) * 0L)) : (int *)8))) && __builtin_choose_expr((sizeof(int) == sizeof (*(8 ? ((void *)((long)((((int)(-1)) < (int)1)) * 0L)) : (int *)8))), (((int)(-1)) < (int)1), 0), node_nr_objs(n), -1) >= 0)': min(x, node_nr_objs(n)) signedness error, fix types or consider umin() before min_t()
>     3256 |                 x = min(x, node_nr_objs(n));
>          |                     ^~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/minmax.h:85:19: note: expanded from macro 'min'
>       85 | #define min(x, y)       __careful_cmp(min, x, y)
>          |                         ^~~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/minmax.h:58:3: note: expanded from macro '__careful_cmp'
>       58 |                 __cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))
>          |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/minmax.h:51:16: note: expanded from macro '__cmp_once'
>       51 |         static_assert(__types_ok(x, y),                 \
>          |         ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       52 |                 #op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \
>          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
>    include/linux/minmax.h:31:2: note: expanded from macro '__is_signed'
>       31 |         __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))),        \
>          |         ^
>    include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
>       77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
>          |                                  ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
>       78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
>          |                                                        ^~~~
>    1 warning and 2 errors generated.
> 
> 
> vim +/node_nr_objs +3256 mm/slub.c
> 
>   3226	
>   3227	static unsigned long count_partial_free_approx(struct kmem_cache_node *n)
>   3228	{
>   3229		unsigned long flags;
>   3230		unsigned long x = 0;
>   3231		struct slab *slab;
>   3232	
>   3233		spin_lock_irqsave(&n->list_lock, flags);
>   3234		if (n->nr_partial <= MAX_PARTIAL_TO_SCAN) {
>   3235			list_for_each_entry(slab, &n->partial, slab_list)
>   3236				x += slab->objects - slab->inuse;
>   3237		} else {
>   3238			/*
>   3239			 * For a long list, approximate the total count of objects in
>   3240			 * it to meet the limit on the number of slabs to scan.
>   3241			 * Scan from both the list's head and tail for better accuracy.
>   3242			 */
>   3243			unsigned long scanned = 0;
>   3244	
>   3245			list_for_each_entry(slab, &n->partial, slab_list) {
>   3246				x += slab->objects - slab->inuse;
>   3247				if (++scanned == MAX_PARTIAL_TO_SCAN / 2)
>   3248					break;
>   3249			}
>   3250			list_for_each_entry_reverse(slab, &n->partial, slab_list) {
>   3251				x += slab->objects - slab->inuse;
>   3252				if (++scanned == MAX_PARTIAL_TO_SCAN)
>   3253					break;
>   3254			}
>   3255			x = mult_frac(x, n->nr_partial, scanned);
>> 3256			x = min(x, node_nr_objs(n));
>   3257		}
>   3258		spin_unlock_irqrestore(&n->list_lock, flags);
>   3259		return x;
>   3260	}
>   3261	
>