Re: [PATCH] hugetlb_cgroup: fix imbalanced css_get and css_put pair for shared mappings

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

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Hi Miaohe,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20210125]
[also build test ERROR on v5.11-rc7]
[cannot apply to linux/master linus/master hnaz-linux-mm/master v5.11-rc7 v5.11-rc6 v5.11-rc5]
[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/hugetlb_cgroup-fix-imbalanced-css_get-and-css_put-pair-for-shared-mappings/20210210-171736
base:    59fa6a163ffabc1bf25c5e0e33899e268a96d3cc
config: arm64-randconfig-r025-20210209 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
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
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/0day-ci/linux/commit/68f4ed1b80aa7c51a921c3ad913ee7e6e00618d0
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Miaohe-Lin/hugetlb_cgroup-fix-imbalanced-css_get-and-css_put-pair-for-shared-mappings/20210210-171736
        git checkout 68f4ed1b80aa7c51a921c3ad913ee7e6e00618d0
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 

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/hugetlb.c:5222:17: error: incomplete definition of type 'struct hugetlb_cgroup'
                           css_put(&h_cg->css);
                                    ~~~~^
   include/linux/hugetlb_cgroup.h:20:8: note: forward declaration of 'struct hugetlb_cgroup'
   struct hugetlb_cgroup;
          ^
   1 error generated.


vim +5222 mm/hugetlb.c

  5091	
  5092	/* Return true if reservation was successful, false otherwise.  */
  5093	bool hugetlb_reserve_pages(struct inode *inode,
  5094						long from, long to,
  5095						struct vm_area_struct *vma,
  5096						vm_flags_t vm_flags)
  5097	{
  5098		long chg, add = -1;
  5099		struct hstate *h = hstate_inode(inode);
  5100		struct hugepage_subpool *spool = subpool_inode(inode);
  5101		struct resv_map *resv_map;
  5102		struct hugetlb_cgroup *h_cg = NULL;
  5103		long gbl_reserve, regions_needed = 0;
  5104	
  5105		/* This should never happen */
  5106		if (from > to) {
  5107			VM_WARN(1, "%s called with a negative range\n", __func__);
  5108			return false;
  5109		}
  5110	
  5111		/*
  5112		 * Only apply hugepage reservation if asked. At fault time, an
  5113		 * attempt will be made for VM_NORESERVE to allocate a page
  5114		 * without using reserves
  5115		 */
  5116		if (vm_flags & VM_NORESERVE)
  5117			return true;
  5118	
  5119		/*
  5120		 * Shared mappings base their reservation on the number of pages that
  5121		 * are already allocated on behalf of the file. Private mappings need
  5122		 * to reserve the full area even if read-only as mprotect() may be
  5123		 * called to make the mapping read-write. Assume !vma is a shm mapping
  5124		 */
  5125		if (!vma || vma->vm_flags & VM_MAYSHARE) {
  5126			/*
  5127			 * resv_map can not be NULL as hugetlb_reserve_pages is only
  5128			 * called for inodes for which resv_maps were created (see
  5129			 * hugetlbfs_get_inode).
  5130			 */
  5131			resv_map = inode_resv_map(inode);
  5132	
  5133			chg = region_chg(resv_map, from, to, &regions_needed);
  5134	
  5135		} else {
  5136			/* Private mapping. */
  5137			resv_map = resv_map_alloc();
  5138			if (!resv_map)
  5139				return false;
  5140	
  5141			chg = to - from;
  5142	
  5143			set_vma_resv_map(vma, resv_map);
  5144			set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
  5145		}
  5146	
  5147		if (chg < 0)
  5148			goto out_err;
  5149	
  5150		if (hugetlb_cgroup_charge_cgroup_rsvd(hstate_index(h),
  5151					chg * pages_per_huge_page(h), &h_cg) < 0)
  5152			goto out_err;
  5153	
  5154		if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) {
  5155			/* For private mappings, the hugetlb_cgroup uncharge info hangs
  5156			 * of the resv_map.
  5157			 */
  5158			resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, h_cg, h);
  5159		}
  5160	
  5161		/*
  5162		 * There must be enough pages in the subpool for the mapping. If
  5163		 * the subpool has a minimum size, there may be some global
  5164		 * reservations already in place (gbl_reserve).
  5165		 */
  5166		gbl_reserve = hugepage_subpool_get_pages(spool, chg);
  5167		if (gbl_reserve < 0)
  5168			goto out_uncharge_cgroup;
  5169	
  5170		/*
  5171		 * Check enough hugepages are available for the reservation.
  5172		 * Hand the pages back to the subpool if there are not
  5173		 */
  5174		if (hugetlb_acct_memory(h, gbl_reserve) < 0)
  5175			goto out_put_pages;
  5176	
  5177		/*
  5178		 * Account for the reservations made. Shared mappings record regions
  5179		 * that have reservations as they are shared by multiple VMAs.
  5180		 * When the last VMA disappears, the region map says how much
  5181		 * the reservation was and the page cache tells how much of
  5182		 * the reservation was consumed. Private mappings are per-VMA and
  5183		 * only the consumed reservations are tracked. When the VMA
  5184		 * disappears, the original reservation is the VMA size and the
  5185		 * consumed reservations are stored in the map. Hence, nothing
  5186		 * else has to be done for private mappings here
  5187		 */
  5188		if (!vma || vma->vm_flags & VM_MAYSHARE) {
  5189			add = region_add(resv_map, from, to, regions_needed, h, h_cg);
  5190	
  5191			if (unlikely(add < 0)) {
  5192				hugetlb_acct_memory(h, -gbl_reserve);
  5193				goto out_put_pages;
  5194			} else if (unlikely(chg > add)) {
  5195				/*
  5196				 * pages in this range were added to the reserve
  5197				 * map between region_chg and region_add.  This
  5198				 * indicates a race with alloc_huge_page.  Adjust
  5199				 * the subpool and reserve counts modified above
  5200				 * based on the difference.
  5201				 */
  5202				long rsv_adjust;
  5203	
  5204				/*
  5205				 * hugetlb_cgroup_uncharge_cgroup_rsvd() will put the
  5206				 * reference to h_cg->css. See comment below for detail.
  5207				 */
  5208				hugetlb_cgroup_uncharge_cgroup_rsvd(
  5209					hstate_index(h),
  5210					(chg - add) * pages_per_huge_page(h), h_cg);
  5211	
  5212				rsv_adjust = hugepage_subpool_put_pages(spool,
  5213									chg - add);
  5214				hugetlb_acct_memory(h, -rsv_adjust);
  5215			} else if (h_cg) {
  5216				/*
  5217				 * The file_regions will hold their own reference to
  5218				 * h_cg->css. So we should release the reference held
  5219				 * via hugetlb_cgroup_charge_cgroup_rsvd() when we are
  5220				 * done.
  5221				 */
> 5222				css_put(&h_cg->css);
  5223			}
  5224		}
  5225		return true;
  5226	
  5227	out_put_pages:
  5228		/* put back original number of pages, chg */
  5229		(void)hugepage_subpool_put_pages(spool, chg);
  5230	out_uncharge_cgroup:
  5231		hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
  5232						    chg * pages_per_huge_page(h), h_cg);
  5233	out_err:
  5234		if (!vma || vma->vm_flags & VM_MAYSHARE)
  5235			/* Only call region_abort if the region_chg succeeded but the
  5236			 * region_add failed or didn't run.
  5237			 */
  5238			if (chg >= 0 && add < 0)
  5239				region_abort(resv_map, from, to, regions_needed);
  5240		if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
  5241			kref_put(&resv_map->refs, resv_map_release);
  5242		return false;
  5243	}
  5244	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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