Re: [PATCH v20 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

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

Hi Muhammad,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on next-20230623]
[cannot apply to linus/master v6.4-rc7]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Muhammad-Usama-Anjum/userfaultfd-UFFD_FEATURE_WP_ASYNC/20230621-171253
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230621072404.2918101-3-usama.anjum%40collabora.com
patch subject: [PATCH v20 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs
config: s390-randconfig-s043-20230622 (https://download.01.org/0day-ci/archive/20230624/202306240610.V4FYUL8b-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230624/202306240610.V4FYUL8b-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306240610.V4FYUL8b-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> fs/proc/task_mmu.c:2209:13: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected struct page_region [noderef] __user *vec @@     got struct page_region * @@
   fs/proc/task_mmu.c:2209:13: sparse:     expected struct page_region [noderef] __user *vec
   fs/proc/task_mmu.c:2209:13: sparse:     got struct page_region *

vim +2209 fs/proc/task_mmu.c

  2193	
  2194	static long do_pagemap_scan(struct mm_struct *mm, unsigned long __arg)
  2195	{
  2196		struct pm_scan_arg __user *uarg = (struct pm_scan_arg __user *)__arg;
  2197		unsigned long long start, end, walk_start, walk_end;
  2198		unsigned long long empty_slots, vec_index = 0;
  2199		struct mmu_notifier_range range;
  2200		struct page_region __user *vec;
  2201		struct pagemap_scan_private p;
  2202		struct pm_scan_arg arg;
  2203		int ret = 0;
  2204	
  2205		if (copy_from_user(&arg, uarg, sizeof(arg)))
  2206			return -EFAULT;
  2207	
  2208		start = untagged_addr((unsigned long)arg.start);
> 2209		vec = (struct page_region *)untagged_addr((unsigned long)arg.vec);
  2210	
  2211		ret = pagemap_scan_args_valid(&arg, start, vec);
  2212		if (ret)
  2213			return ret;
  2214	
  2215		end = start + arg.len;
  2216		p.max_pages = arg.max_pages;
  2217		p.found_pages = 0;
  2218		p.required_mask = arg.required_mask;
  2219		p.anyof_mask = arg.anyof_mask;
  2220		p.excluded_mask = arg.excluded_mask;
  2221		p.return_mask = arg.return_mask;
  2222		p.flags = arg.flags;
  2223		p.flags |= ((p.required_mask | p.anyof_mask | p.excluded_mask) &
  2224			    PAGE_IS_WRITTEN) ? PM_SCAN_REQUIRE_UFFD : 0;
  2225		p.cur_buf.start = p.cur_buf.len = p.cur_buf.flags = 0;
  2226		p.vec_buf = NULL;
  2227		p.vec_buf_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
  2228	
  2229		/*
  2230		 * Allocate smaller buffer to get output from inside the page walk
  2231		 * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
  2232		 * we want to return output to user in compact form where no two
  2233		 * consecutive regions should be continuous and have the same flags.
  2234		 * So store the latest element in p.cur_buf between different walks and
  2235		 * store the p.cur_buf at the end of the walk to the user buffer.
  2236		 */
  2237		if (IS_PM_SCAN_GET(p.flags)) {
  2238			p.vec_buf = kmalloc_array(p.vec_buf_len, sizeof(*p.vec_buf),
  2239						  GFP_KERNEL);
  2240			if (!p.vec_buf)
  2241				return -ENOMEM;
  2242		}
  2243	
  2244		if (IS_PM_SCAN_WP(p.flags)) {
  2245			mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
  2246						mm, start, end);
  2247			mmu_notifier_invalidate_range_start(&range);
  2248		}
  2249	
  2250		walk_start = walk_end = start;
  2251		while (walk_end < end && !ret) {
  2252			if (IS_PM_SCAN_GET(p.flags)) {
  2253				p.vec_buf_index = 0;
  2254	
  2255				/*
  2256				 * All data is copied to cur_buf first. When more data
  2257				 * is found, we push cur_buf to vec_buf and copy new
  2258				 * data to cur_buf. Subtract 1 from length as the
  2259				 * index of cur_buf isn't counted in length.
  2260				 */
  2261				empty_slots = arg.vec_len - vec_index;
  2262				p.vec_buf_len = min(p.vec_buf_len, empty_slots - 1);
  2263			}
  2264	
  2265			walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
  2266			if (walk_end > end)
  2267				walk_end = end;
  2268	
  2269			ret = mmap_read_lock_killable(mm);
  2270			if (ret)
  2271				goto free_data;
  2272			ret = walk_page_range(mm, walk_start, walk_end,
  2273					      &pagemap_scan_ops, &p);
  2274			mmap_read_unlock(mm);
  2275	
  2276			if (ret && ret != PM_SCAN_BUFFER_FULL &&
  2277			    ret != PM_SCAN_FOUND_MAX_PAGES)
  2278				goto free_data;
  2279	
  2280			walk_start = walk_end;
  2281			if (IS_PM_SCAN_GET(p.flags) && p.vec_buf_index) {
  2282				if (copy_to_user(&vec[vec_index], p.vec_buf,
  2283						 p.vec_buf_index * sizeof(*p.vec_buf))) {
  2284					/*
  2285					 * Return error even though the OP succeeded
  2286					 */
  2287					ret = -EFAULT;
  2288					goto free_data;
  2289				}
  2290				vec_index += p.vec_buf_index;
  2291			}
  2292		}
  2293	
  2294		if (p.cur_buf.len) {
  2295			if (copy_to_user(&vec[vec_index], &p.cur_buf, sizeof(p.cur_buf))) {
  2296				ret = -EFAULT;
  2297				goto free_data;
  2298			}
  2299			vec_index++;
  2300		}
  2301	
  2302		ret = vec_index;
  2303	
  2304	free_data:
  2305		if (IS_PM_SCAN_WP(p.flags))
  2306			mmu_notifier_invalidate_range_end(&range);
  2307	
  2308		kfree(p.vec_buf);
  2309		return ret;
  2310	}
  2311	

-- 
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