Re: [PATCH v2] mm/mempolicy: fix mpol_new leak in shared_policy_replace

[kernel test robot <lkp@intel.com>]

Hi Miaohe,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linux/master]
[also build test ERROR on linus/master v5.17]
[cannot apply to hnaz-mm/master next-20220321]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Miaohe-Lin/mm-mempolicy-fix-mpol_new-leak-in-shared_policy_replace/20220321-200100
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2c271fe77d52a0555161926c232cd5bc07178b39
config: ia64-defconfig (https://download.01.org/0day-ci/archive/20220322/202203220201.toJrpBkF-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/9a91a8a7964a3af0b60f08dc38b7815e5118206a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Miaohe-Lin/mm-mempolicy-fix-mpol_new-leak-in-shared_policy_replace/20220321-200100
        git checkout 9a91a8a7964a3af0b60f08dc38b7815e5118206a
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=ia64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   mm/mempolicy.c: In function 'shared_policy_replace':
>> mm/mempolicy.c:2745:22: error: passing argument 1 of 'refcount_set' from incompatible pointer type [-Werror=incompatible-pointer-types]
    2745 |         refcount_set(&mpol_new->refcnt, 1);
         |                      ^~~~~~~~~~~~~~~~~
         |                      |
         |                      atomic_t *
   In file included from include/linux/pid.h:7,
                    from include/linux/sched.h:14,
                    from include/linux/mempolicy.h:9,
                    from mm/mempolicy.c:73:
   include/linux/refcount.h:134:45: note: expected 'refcount_t *' {aka 'struct refcount_struct *'} but argument is of type 'atomic_t *'
     134 | static inline void refcount_set(refcount_t *r, int n)
         |                                 ~~~~~~~~~~~~^
   cc1: some warnings being treated as errors


vim +/refcount_set +2745 mm/mempolicy.c

  2681	
  2682	/* Replace a policy range. */
  2683	static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
  2684					 unsigned long end, struct sp_node *new)
  2685	{
  2686		struct sp_node *n;
  2687		struct sp_node *n_new = NULL;
  2688		struct mempolicy *mpol_new = NULL;
  2689		int ret = 0;
  2690	
  2691	restart:
  2692		write_lock(&sp->lock);
  2693		n = sp_lookup(sp, start, end);
  2694		/* Take care of old policies in the same range. */
  2695		while (n && n->start < end) {
  2696			struct rb_node *next = rb_next(&n->nd);
  2697			if (n->start >= start) {
  2698				if (n->end <= end)
  2699					sp_delete(sp, n);
  2700				else
  2701					n->start = end;
  2702			} else {
  2703				/* Old policy spanning whole new range. */
  2704				if (n->end > end) {
  2705					if (!n_new)
  2706						goto alloc_new;
  2707	
  2708					*mpol_new = *n->policy;
  2709					atomic_set(&mpol_new->refcnt, 1);
  2710					sp_node_init(n_new, end, n->end, mpol_new);
  2711					n->end = start;
  2712					sp_insert(sp, n_new);
  2713					n_new = NULL;
  2714					mpol_new = NULL;
  2715					break;
  2716				} else
  2717					n->end = start;
  2718			}
  2719			if (!next)
  2720				break;
  2721			n = rb_entry(next, struct sp_node, nd);
  2722		}
  2723		if (new)
  2724			sp_insert(sp, new);
  2725		write_unlock(&sp->lock);
  2726		ret = 0;
  2727	
  2728	err_out:
  2729		if (mpol_new)
  2730			mpol_put(mpol_new);
  2731		if (n_new)
  2732			kmem_cache_free(sn_cache, n_new);
  2733	
  2734		return ret;
  2735	
  2736	alloc_new:
  2737		write_unlock(&sp->lock);
  2738		ret = -ENOMEM;
  2739		n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
  2740		if (!n_new)
  2741			goto err_out;
  2742		mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
  2743		if (!mpol_new)
  2744			goto err_out;
> 2745		refcount_set(&mpol_new->refcnt, 1);
  2746		goto restart;
  2747	}
  2748	

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