• Yafang Shao's avatar
    mm, memcg: fix build error around the usage of kmem_caches · a87425a3
    Yafang Shao authored
    When I manually set default n to MEMCG_KMEM in init/Kconfig, bellow error
    occurs,
    
      mm/slab_common.c: In function 'memcg_slab_start':
      mm/slab_common.c:1530:30: error: 'struct mem_cgroup' has no member named
      'kmem_caches'
        return seq_list_start(&memcg->kmem_caches, *pos);
                                    ^
      mm/slab_common.c: In function 'memcg_slab_next':
      mm/slab_common.c:1537:32: error: 'struct mem_cgroup' has no member named
      'kmem_caches'
        return seq_list_next(p, &memcg->kmem_caches, pos);
                                      ^
      mm/slab_common.c: In function 'memcg_slab_show':
      mm/slab_common.c:1551:16: error: 'struct mem_cgroup' has no member named
      'kmem_caches'
        if (p == memcg->kmem_caches.next)
                      ^
        CC      arch/x86/xen/smp.o
      mm/slab_common.c: In function 'memcg_slab_start':
      mm/slab_common.c:1531:1: warning: control reaches end of non-void function
      [-Wreturn-type]
       }
       ^
      mm/slab_common.c: In function 'memcg_slab_next':
      mm/slab_common.c:1538:1: warning: control reaches end of non-void function
      [-Wreturn-type]
       }
       ^
    
    That's because kmem_caches is defined only when CONFIG_MEMCG_KMEM is set,
    while memcg_slab_start() will use it no matter CONFIG_MEMCG_KMEM is defined
    or not.
    
    By the way, the reason I mannuly undefined CONFIG_MEMCG_KMEM is to verify
    whether my some other code change is still stable when CONFIG_MEMCG_KMEM is
    not set. Unfortunately, the existing code has been already unstable since
    v4.11.
    
    Fixes: bc2791f8 ("slab: link memcg kmem_caches on their associated memory cgroup")
    Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Michal Hocko <mhocko@kernel.org>
    Link: http://lkml.kernel.org/r/1580970260-2045-1-git-send-email-laoar.shao@gmail.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    a87425a3
slab_common.c 44 KB