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Subject[PATCH] /proc/PID/smaps: Add PMD migration entry parsing
Date
From: Huang Ying <ying.huang@intel.com>

Now, when read /proc/PID/smaps, the PMD migration entry in page table is simply
ignored. To improve the accuracy of /proc/PID/smaps, its parsing and processing
is added.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
---
fs/proc/task_mmu.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8d382d4ec067..b5b3aef8cb3b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -548,8 +548,17 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
bool locked = !!(vma->vm_flags & VM_LOCKED);
struct page *page;

- /* FOLL_DUMP will return -EFAULT on huge zero page */
- page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
+ if (pmd_present(*pmd)) {
+ /* FOLL_DUMP will return -EFAULT on huge zero page */
+ page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
+ } else if (unlikely(is_swap_pmd(*pmd))) {
+ swp_entry_t entry = pmd_to_swp_entry(*pmd);
+
+ VM_BUG_ON(!is_migration_entry(entry));
+ page = migration_entry_to_page(entry);
+ } else {
+ return;
+ }
if (IS_ERR_OR_NULL(page))
return;
if (PageAnon(page))
@@ -578,8 +587,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,

ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
- if (pmd_present(*pmd))
- smaps_pmd_entry(pmd, addr, walk);
+ smaps_pmd_entry(pmd, addr, walk);
spin_unlock(ptl);
goto out;
}
--
2.25.0
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