Re: [PATCHv2 2/2] Add /proc/PID/{smaps, numa_maps} support for DAX

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

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Hi Fan,

Thank you for the patch! Yet we hit a small issue.
[auto build test WARNING on linus/master]
[also build test WARNING on v4.14-rc6 next-20171018]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Fan-Du/proc-mm-export-PTE-sizes-directly-in-smaps/20171027-141157
config: x86_64-randconfig-x011-201743 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   fs/proc/task_mmu.c: In function 'gather_pte_stats':
>> fs/proc/task_mmu.c:1805:6: warning: 'page' may be used uninitialized in this function [-Wmaybe-uninitialized]
      if (!page)
         ^

vim +/page +1805 fs/proc/task_mmu.c

28093f9f3 Gerald Schaefer    2016-04-28  1771  
f69ff943d Stephen Wilson     2011-05-24  1772  static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
f69ff943d Stephen Wilson     2011-05-24  1773  		unsigned long end, struct mm_walk *walk)
f69ff943d Stephen Wilson     2011-05-24  1774  {
d85f4d6d3 Naoya Horiguchi    2015-02-11  1775  	struct numa_maps *md = walk->private;
d85f4d6d3 Naoya Horiguchi    2015-02-11  1776  	struct vm_area_struct *vma = walk->vma;
f69ff943d Stephen Wilson     2011-05-24  1777  	spinlock_t *ptl;
f69ff943d Stephen Wilson     2011-05-24  1778  	pte_t *orig_pte;
f69ff943d Stephen Wilson     2011-05-24  1779  	pte_t *pte;
3bf801467 Fan Du             2017-10-24  1780  	struct page *page;
f69ff943d Stephen Wilson     2011-05-24  1781  
28093f9f3 Gerald Schaefer    2016-04-28  1782  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
b6ec57f4b Kirill A. Shutemov 2016-01-21  1783  	ptl = pmd_trans_huge_lock(pmd, vma);
b6ec57f4b Kirill A. Shutemov 2016-01-21  1784  	if (ptl) {
3bf801467 Fan Du             2017-10-24  1785  		if (!vma_is_dax(vma))
28093f9f3 Gerald Schaefer    2016-04-28  1786  			page = can_gather_numa_stats_pmd(*pmd, vma, addr);
3bf801467 Fan Du             2017-10-24  1787  		else if (pmd_devmap(*pmd))
3bf801467 Fan Du             2017-10-24  1788  			page = pmd_page(*pmd);
32ef43848 Dave Hansen        2011-09-20  1789  		if (page)
28093f9f3 Gerald Schaefer    2016-04-28  1790  			gather_stats(page, md, pmd_dirty(*pmd),
32ef43848 Dave Hansen        2011-09-20  1791  				     HPAGE_PMD_SIZE/PAGE_SIZE);
bf929152e Kirill A. Shutemov 2013-11-14  1792  		spin_unlock(ptl);
32ef43848 Dave Hansen        2011-09-20  1793  		return 0;
32ef43848 Dave Hansen        2011-09-20  1794  	}
32ef43848 Dave Hansen        2011-09-20  1795  
1a5a9906d Andrea Arcangeli   2012-03-21  1796  	if (pmd_trans_unstable(pmd))
1a5a9906d Andrea Arcangeli   2012-03-21  1797  		return 0;
28093f9f3 Gerald Schaefer    2016-04-28  1798  #endif
f69ff943d Stephen Wilson     2011-05-24  1799  	orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
f69ff943d Stephen Wilson     2011-05-24  1800  	do {
3bf801467 Fan Du             2017-10-24  1801  		if (!vma_is_dax(vma))
3bf801467 Fan Du             2017-10-24  1802  			page = can_gather_numa_stats(*pte, vma, addr);
3bf801467 Fan Du             2017-10-24  1803  		else if (pte_devmap(*pte))
3bf801467 Fan Du             2017-10-24  1804  			page = pte_page(*pte);
f69ff943d Stephen Wilson     2011-05-24 @1805  		if (!page)
f69ff943d Stephen Wilson     2011-05-24  1806  			continue;
eb4866d00 Dave Hansen        2011-09-20  1807  		gather_stats(page, md, pte_dirty(*pte), 1);
f69ff943d Stephen Wilson     2011-05-24  1808  
f69ff943d Stephen Wilson     2011-05-24  1809  	} while (pte++, addr += PAGE_SIZE, addr != end);
f69ff943d Stephen Wilson     2011-05-24  1810  	pte_unmap_unlock(orig_pte, ptl);
a66c0410b Hugh Dickins       2016-12-12  1811  	cond_resched();
f69ff943d Stephen Wilson     2011-05-24  1812  	return 0;
f69ff943d Stephen Wilson     2011-05-24  1813  }
f69ff943d Stephen Wilson     2011-05-24  1814  #ifdef CONFIG_HUGETLB_PAGE
632fd60fe Naoya Horiguchi    2015-02-11  1815  static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
f69ff943d Stephen Wilson     2011-05-24  1816  		unsigned long addr, unsigned long end, struct mm_walk *walk)
f69ff943d Stephen Wilson     2011-05-24  1817  {
5c2ff95e4 Michael Holzheu    2016-02-02  1818  	pte_t huge_pte = huge_ptep_get(pte);
f69ff943d Stephen Wilson     2011-05-24  1819  	struct numa_maps *md;
f69ff943d Stephen Wilson     2011-05-24  1820  	struct page *page;
f69ff943d Stephen Wilson     2011-05-24  1821  
5c2ff95e4 Michael Holzheu    2016-02-02  1822  	if (!pte_present(huge_pte))
f69ff943d Stephen Wilson     2011-05-24  1823  		return 0;
f69ff943d Stephen Wilson     2011-05-24  1824  
5c2ff95e4 Michael Holzheu    2016-02-02  1825  	page = pte_page(huge_pte);
f69ff943d Stephen Wilson     2011-05-24  1826  	if (!page)
f69ff943d Stephen Wilson     2011-05-24  1827  		return 0;
f69ff943d Stephen Wilson     2011-05-24  1828  
f69ff943d Stephen Wilson     2011-05-24  1829  	md = walk->private;
5c2ff95e4 Michael Holzheu    2016-02-02  1830  	gather_stats(page, md, pte_dirty(huge_pte), 1);
f69ff943d Stephen Wilson     2011-05-24  1831  	return 0;
f69ff943d Stephen Wilson     2011-05-24  1832  }
f69ff943d Stephen Wilson     2011-05-24  1833  

:::::: The code at line 1805 was first introduced by commit
:::::: f69ff943df6972aae96c10733b6847fa094d8a59 mm: proc: move show_numa_map() to fs/proc/task_mmu.c

:::::: TO: Stephen Wilson <wilsons@start.ca>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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0-DAY kernel test infrastructure                Open Source Technology Center
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