Hi,
On 18.04.2018 15:55, kbuild test robot wrote:
> Hi Kirill,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on mmotm/master]
> [also build test WARNING on next-20180418]
> [cannot apply to v4.17-rc1]
> [if your patch is applied to the wrong git tree, please drop us a note to
> help improve the system]
>
> url:
> https://github.com/0day-ci/linux/commits/Kirill-Tkhai/Improve-shrink_slab-scalability-old-complexity-was-O-n-2-new-is-O-n/20180418-184501
> base: git://git.cmpxchg.org/linux-mmotm.git master
> config: x86_64-randconfig-x011-201815 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
> reproduce:
> # save the attached .config to linux build tree
> make ARCH=x86_64
>
> Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
> http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
>
> All warnings (new ones prefixed by >>):
>
> mm/memcontrol.c: In function 'expand_shrinker_maps':
>>> mm/memcontrol.c:402:9: warning: 'ret' may be used uninitialized in this
>>> function [-Wmaybe-uninitialized]
> return ret;> ^~~
thanks for reporting this. Actually in terms of kernel it's a false positive
(since this function is called at time, when for_each_node() iterates not empty
list), but of course, I'll add ret initialization to silence the compiler.
This should not prevent the review of the patchset, so I'm waiting for people's
comments about it before resending v3.
>
> vim +/ret +402 mm/memcontrol.c
>
> 377
> 378 int expand_shrinker_maps(int old_nr, int nr)
> 379 {
> 380 int id, size, old_size, node, ret;
> 381 struct mem_cgroup *memcg;
> 382
> 383 old_size = old_nr / BITS_PER_BYTE;
> 384 size = nr / BITS_PER_BYTE;
> 385
> 386 down_write(&shrinkers_max_nr_rwsem);
> 387 for_each_node(node) {
> 388 idr_for_each_entry(&mem_cgroup_idr, memcg, id) {
> 389 if (id == 1)
> 390 memcg = NULL;
> 391 ret = memcg_expand_maps(memcg, node,
> size, old_size);
> 392 if (ret)
> 393 goto unlock;
> 394 }
> 395
> 396 /* root_mem_cgroup is not initialized yet */
> 397 if (id == 0)
> 398 ret = memcg_expand_maps(NULL, node,
> size, old_size);
> 399 }
> 400 unlock:
> 401 up_write(&shrinkers_max_nr_rwsem);
> > 402 return ret;
> 403 }
> 404 #else /* CONFIG_SLOB */
> 405 static void get_shrinkers_max_nr(void) { }
> 406 static void put_shrinkers_max_nr(void) { }
> 407
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
Kirill
