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

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-im... base: 59fa6a163ffabc1bf25c5e0e33899e268a96d3cc config: x86_64-randconfig-c002-20210209 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/68f4ed1b80aa7c51a921c3ad913ee7e6e... 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 make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): mm/hugetlb.c: In function 'hugetlb_reserve_pages': 5222 | css_put(&h_cg->css); | ^~ 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 */ 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