mm, /proc/pid/pagemap: fix soft dirty marking for PMD migration entry

When the pagetable is walked in the implementation of /proc/<pid>/pagemap,
pmd_soft_dirty() is used for both the PMD huge page map and the PMD
migration entries.  That is wrong, pmd_swp_soft_dirty() should be used
for the PMD migration entries instead because the different page table
entry flag is used.

As a result, /proc/pid/pagemap may report incorrect soft dirty information
for PMD migration entries.

Link: http://lkml.kernel.org/r/20171017081818.31795-1-ying.huang@intel.com
Fixes: 84c3fc4e9c56 ("mm: thp: check pmd migration entry in common path")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 280282b05bc7..6744bd706ecf 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1311,13 +1311,15 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
                 pmd_t pmd = *pmdp;
                 struct page *page = NULL;
 
-                if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(pmd))
+                if (vma->vm_flags & VM_SOFTDIRTY)
                         flags |= PM_SOFT_DIRTY;
 
                 if (pmd_present(pmd)) {
                         page = pmd_page(pmd);
 
                         flags |= PM_PRESENT;
+                        if (pmd_soft_dirty(pmd))
+                                flags |= PM_SOFT_DIRTY;
                         if (pm->show_pfn)
                                 frame = pmd_pfn(pmd) +
                                         ((addr & ~PMD_MASK) >> PAGE_SHIFT);
@@ -1329,6 +1331,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
                         frame = swp_type(entry) |
                                 (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
                         flags |= PM_SWAP;
+                        if (pmd_swp_soft_dirty(pmd))
+                                flags |= PM_SOFT_DIRTY;
                         VM_BUG_ON(!is_pmd_migration_entry(pmd));
                         page = migration_entry_to_page(entry);
                 }