Re: [v2] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning
From: kernel test robot
Date: Sat Jul 22 2023 - 09:57:13 EST
Hi Michał,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on linus/master v6.5-rc2 next-20230721]
[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/Micha-Miros-aw/fs-proc-task_mmu-Implement-IOCTL-for-efficient-page-table-scanning/20230722-082500
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/ZLshsAj5PbsEAHhP%40qmqm.qmqm.pl
patch subject: [v2] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20230722/202307222107.GdtIG4nq-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce: (https://download.01.org/0day-ci/archive/20230722/202307222107.GdtIG4nq-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307222107.GdtIG4nq-lkp@xxxxxxxxx/
All errors (new ones prefixed by >>):
fs/proc/task_mmu.c:1921:6: error: call to undeclared function 'userfaultfd_wp_async'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
if (userfaultfd_wp_async(vma) && userfaultfd_wp_use_markers(vma))
^
>> fs/proc/task_mmu.c:2047:13: error: use of undeclared identifier 'addr'
if (end != addr + HPAGE_SIZE) {
^
2 errors generated.
vim +/addr +2047 fs/proc/task_mmu.c
1913
1914 static int pagemap_scan_test_walk(unsigned long start, unsigned long end,
1915 struct mm_walk *walk)
1916 {
1917 struct pagemap_scan_private *p = walk->private;
1918 struct vm_area_struct *vma = walk->vma;
1919 unsigned long vma_category = 0;
1920
> 1921 if (userfaultfd_wp_async(vma) && userfaultfd_wp_use_markers(vma))
1922 vma_category |= PAGE_IS_WPASYNC;
1923 else if (p->arg.flags & PM_SCAN_CHECK_WPASYNC)
1924 return -EPERM;
1925
1926 if (vma->vm_flags & VM_PFNMAP)
1927 return 1;
1928
1929 if (!pagemap_scan_is_interesting_vma(vma_category, p))
1930 return 1;
1931
1932 p->cur_vma_category = vma_category;
1933 return 0;
1934 }
1935
1936 static bool pagemap_scan_push_range(unsigned long categories,
1937 struct pagemap_scan_private *p,
1938 unsigned long addr, unsigned long end)
1939 {
1940 struct page_region *cur_buf = &p->cur_buf;
1941
1942 /*
1943 * When there is no output buffer provided at all, the sentinel values
1944 * won't match here. There is no other way for `cur_buf->end` to be
1945 * non-zero other than it being non-empty.
1946 */
1947 if (addr == cur_buf->end && categories == cur_buf->categories) {
1948 cur_buf->end = end;
1949 return true;
1950 }
1951
1952 if (cur_buf->end) {
1953 if (p->vec_buf_index >= p->vec_buf_len)
1954 return false;
1955
1956 memcpy(&p->vec_buf[p->vec_buf_index], cur_buf,
1957 sizeof(*p->vec_buf));
1958 ++p->vec_buf_index;
1959 }
1960
1961 cur_buf->start = addr;
1962 cur_buf->end = end;
1963 cur_buf->categories = categories;
1964 return true;
1965 }
1966
1967 static void pagemap_scan_backout_range(struct pagemap_scan_private *p,
1968 unsigned long addr, unsigned long end)
1969 {
1970 struct page_region *cur_buf = &p->cur_buf;
1971
1972 if (cur_buf->start != addr)
1973 cur_buf->end = addr;
1974 else
1975 cur_buf->start = cur_buf->end = 0;
1976
1977 p->end_addr = 0;
1978 p->found_pages -= (end - addr) / PAGE_SIZE;
1979 }
1980
1981 static int pagemap_scan_output(unsigned long categories,
1982 struct pagemap_scan_private *p,
1983 unsigned long addr, unsigned long *end)
1984 {
1985 unsigned long n_pages, total_pages;
1986 int ret = 0;
1987
1988 if (!pagemap_scan_is_interesting_page(categories, p)) {
1989 *end = addr;
1990 return 0;
1991 }
1992
1993 if (!p->vec_buf)
1994 return 0;
1995
1996 categories &= p->arg.return_mask;
1997
1998 n_pages = (*end - addr) / PAGE_SIZE;
1999 if (check_add_overflow(p->found_pages, n_pages, &total_pages) || total_pages > p->arg.max_pages) {
2000 size_t n_too_much = total_pages - p->arg.max_pages;
2001 *end -= n_too_much * PAGE_SIZE;
2002 n_pages -= n_too_much;
2003 ret = -ENOSPC;
2004 }
2005
2006 if (!pagemap_scan_push_range(categories, p, addr, *end)) {
2007 *end = addr;
2008 n_pages = 0;
2009 ret = -ENOSPC;
2010 }
2011
2012 p->found_pages += n_pages;
2013 if (ret)
2014 p->end_addr = *end;
2015 return ret;
2016 }
2017
2018 static int pagemap_scan_thp_entry(pmd_t *pmd, unsigned long start,
2019 unsigned long end, struct mm_walk *walk)
2020 {
2021 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
2022 struct pagemap_scan_private *p = walk->private;
2023 struct vm_area_struct *vma = walk->vma;
2024 unsigned long categories;
2025 spinlock_t *ptl;
2026 int ret = 0;
2027
2028 ptl = pmd_trans_huge_lock(pmd, vma);
2029 if (!ptl)
2030 return -ENOENT;
2031
2032 categories = p->cur_vma_category | pagemap_thp_category(*pmd);
2033
2034 ret = pagemap_scan_output(categories, p, start, &end);
2035 if (start == end)
2036 goto out_unlock;
2037
2038 if (~p->arg.flags & PM_SCAN_WP_MATCHING)
2039 goto out_unlock;
2040 if (~categories & PAGE_IS_WRITTEN)
2041 goto out_unlock;
2042
2043 /*
2044 * Break huge page into small pages if the WP operation
2045 * need to be performed is on a portion of the huge page.
2046 */
> 2047 if (end != addr + HPAGE_SIZE) {
2048 spin_unlock(ptl);
2049 split_huge_pmd(vma, pmd, start);
2050 pagemap_scan_backout_range(p, start, end);
2051 return -ENOENT;
2052 }
2053
2054 make_uffd_wp_pmd(vma, start, pmd);
2055 flush_tlb_range(vma, start, end);
2056 out_unlock:
2057 spin_unlock(ptl);
2058 return ret;
2059 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
2060 return -ENOENT;
2061 #endif
2062 }
2063
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