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Subject: Re: [PATCH 03/10] mm: Assign memcg-aware shrinkers bitmap to memcg
To:     kbuild test robot <lkp@intel.com>
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        linux-mm@kvack.org, willy@infradead.org
References: <152163850081.21546.6969747084834474733.stgit@localhost.localdomain>
 <201803231640.37BGHC6o%fengguang.wu@intel.com>
From:   Kirill Tkhai <ktkhai@virtuozzo.com>
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Date:   Fri, 23 Mar 2018 14:26:04 +0300
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On 23.03.2018 12:06, 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 v4.16-rc6 next-20180322]
> [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/20180323-052754
> base:   git://git.cmpxchg.org/linux-mmotm.git master
> reproduce:
>         # apt-get install sparse
>         make ARCH=x86_64 allmodconfig
>         make C=1 CF=-D__CHECK_ENDIAN__
> 
> 
> sparse warnings: (new ones prefixed by >>)
> 
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:79:1: sparse: incorrect type in argument 3 (different base types) @@    expected unsigned long [unsigned] flags @@    got resunsigned long [unsigned] flags @@
>    include/trace/events/vmscan.h:79:1:    expected unsigned long [unsigned] flags
>    include/trace/events/vmscan.h:79:1:    got restricted gfp_t [usertype] gfp_flags
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:106:1: sparse: incorrect type in argument 3 (different base types) @@    expected unsigned long [unsigned] flags @@    got resunsigned long [unsigned] flags @@
>    include/trace/events/vmscan.h:106:1:    expected unsigned long [unsigned] flags
>    include/trace/events/vmscan.h:106:1:    got restricted gfp_t [usertype] gfp_flags
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: cast from restricted gfp_t
>    include/trace/events/vmscan.h:196:1: sparse: too many warnings
>>> mm/vmscan.c:231:15: sparse: incompatible types in conditional expression (different address spaces)
>>> mm/vmscan.c:231:15: sparse: cast from unknown type
>>> mm/vmscan.c:231:15: sparse: incompatible types in conditional expression (different address spaces)
>>> mm/vmscan.c:231:15: sparse: incompatible types in conditional expression (different address spaces)
>>> mm/vmscan.c:231:15: sparse: cast from unknown type
> 
> vim +231 mm/vmscan.c

Yeah, thanks for report.

> 
>    205	
>    206	static int memcg_expand_maps(struct mem_cgroup *memcg, int size, int old_size)
>    207	{
>    208		struct shrinkers_map *new, *old;
>    209		int i;
>    210	
>    211		new = kvmalloc(sizeof(*new) + nr_node_ids * sizeof(new->map[0]),
>    212				GFP_KERNEL);
>    213		if (!new)
>    214			return -ENOMEM;
>    215	
>    216		for (i = 0; i < nr_node_ids; i++) {
>    217			new->map[i] = kvmalloc_node(size, GFP_KERNEL, i);
>    218			if (!new->map[i]) {
>    219				while (--i >= 0)
>    220					kvfree(new->map[i]);
>    221				kvfree(new);
>    222				return -ENOMEM;
>    223			}
>    224	
>    225			/* Set all old bits, clear all new bits */
>    226			memset(new->map[i], (int)0xff, old_size);
>    227			memset((void *)new->map[i] + old_size, 0, size - old_size);
>    228		}
>    229	
>    230		lockdep_assert_held(&bitmap_rwsem);
>  > 231		old = rcu_dereference_protected(SHRINKERS_MAP(memcg), true);
>    232	
>    233		/*
>    234		 * We don't want to use rcu_read_lock() in shrink_slab().
>    235		 * Since expansion happens rare, we may just take the lock
>    236		 * here.
>    237		 */
>    238		if (old)
>    239			down_write(&shrinker_rwsem);
>    240	
>    241		if (memcg)
>    242			rcu_assign_pointer(memcg->shrinkers_map, new);
>    243		else
>    244			rcu_assign_pointer(root_shrinkers_map, new);
>    245	
>    246		if (old) {
>    247			up_write(&shrinker_rwsem);
>    248			call_rcu(&old->rcu, kvfree_map_rcu);
>    249		}
>    250	
>    251		return 0;
>    252	}
>    253	
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
>