@@ -440,7 +440,8 @@ static void smaps_page_accumulate(struct
}
static void smaps_account(struct mem_size_stats *mss, struct page *page,
- bool compound, bool young, bool dirty, bool locked)
+ bool compound, bool young, bool dirty, bool locked,
+ bool migration)
{
int i, nr = compound ? compound_nr(page) : 1;
unsigned long size = nr * PAGE_SIZE;
@@ -467,8 +468,15 @@ static void smaps_account(struct mem_siz
* page_count(page) == 1 guarantees the page is mapped exactly once.
* If any subpage of the compound page mapped with PTE it would elevate
* page_count().
+ *
+ * The page_mapcount() is called to get a snapshot of the mapcount.
+ * Without holding the page lock this snapshot can be slightly wrong as
+ * we cannot always read the mapcount atomically. It is not safe to
+ * call page_mapcount() even with PTL held if the page is not mapped,
+ * especially for migration entries. Treat regular migration entries
+ * as mapcount == 1.
*/
- if (page_count(page) == 1) {
+ if ((page_count(page) == 1) || migration) {
smaps_page_accumulate(mss, page, size, size << PSS_SHIFT, dirty,
locked, true);
return;
@@ -517,6 +525,7 @@ static void smaps_pte_entry(pte_t *pte,
struct vm_area_struct *vma = walk->vma;
bool locked = !!(vma->vm_flags & VM_LOCKED);
struct page *page = NULL;
+ bool migration = false;
if (pte_present(*pte)) {
page = vm_normal_page(vma, addr, *pte);
@@ -536,8 +545,11 @@ static void smaps_pte_entry(pte_t *pte,
} else {
mss->swap_pss += (u64)PAGE_SIZE << PSS_SHIFT;
}
- } else if (is_pfn_swap_entry(swpent))
+ } else if (is_pfn_swap_entry(swpent)) {
+ if (is_migration_entry(swpent))
+ migration = true;
page = pfn_swap_entry_to_page(swpent);
+ }
} else {
smaps_pte_hole_lookup(addr, walk);
return;
@@ -546,7 +558,8 @@ static void smaps_pte_entry(pte_t *pte,
if (!page)
return;
- smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), locked);
+ smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte),
+ locked, migration);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -557,6 +570,7 @@ static void smaps_pmd_entry(pmd_t *pmd,
struct vm_area_struct *vma = walk->vma;
bool locked = !!(vma->vm_flags & VM_LOCKED);
struct page *page = NULL;
+ bool migration = false;
if (pmd_present(*pmd)) {
/* FOLL_DUMP will return -EFAULT on huge zero page */
@@ -564,8 +578,10 @@ static void smaps_pmd_entry(pmd_t *pmd,
} else if (unlikely(thp_migration_supported() && is_swap_pmd(*pmd))) {
swp_entry_t entry = pmd_to_swp_entry(*pmd);
- if (is_migration_entry(entry))
+ if (is_migration_entry(entry)) {
+ migration = true;
page = pfn_swap_entry_to_page(entry);
+ }
}
if (IS_ERR_OR_NULL(page))
return;
@@ -577,7 +593,9 @@ static void smaps_pmd_entry(pmd_t *pmd,
/* pass */;
else
mss->file_thp += HPAGE_PMD_SIZE;
- smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd), locked);
+
+ smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd),
+ locked, migration);
}
#else
static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
@@ -1378,6 +1396,7 @@ static pagemap_entry_t pte_to_pagemap_en
{
u64 frame = 0, flags = 0;
struct page *page = NULL;
+ bool migration = false;
if (pte_present(pte)) {
if (pm->show_pfn)
@@ -1399,13 +1418,14 @@ static pagemap_entry_t pte_to_pagemap_en
frame = swp_type(entry) |
(swp_offset(entry) << MAX_SWAPFILES_SHIFT);
flags |= PM_SWAP;
+ migration = is_migration_entry(entry);
if (is_pfn_swap_entry(entry))
page = pfn_swap_entry_to_page(entry);
}
if (page && !PageAnon(page))
flags |= PM_FILE;
- if (page && page_mapcount(page) == 1)
+ if (page && !migration && page_mapcount(page) == 1)
flags |= PM_MMAP_EXCLUSIVE;
if (vma->vm_flags & VM_SOFTDIRTY)
flags |= PM_SOFT_DIRTY;
@@ -1421,8 +1441,9 @@ static int pagemap_pmd_range(pmd_t *pmdp
spinlock_t *ptl;
pte_t *pte, *orig_pte;
int err = 0;
-
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ bool migration = false;
+
ptl = pmd_trans_huge_lock(pmdp, vma);
if (ptl) {
u64 flags = 0, frame = 0;
@@ -1461,11 +1482,12 @@ static int pagemap_pmd_range(pmd_t *pmdp
if (pmd_swp_uffd_wp(pmd))
flags |= PM_UFFD_WP;
VM_BUG_ON(!is_pmd_migration_entry(pmd));
+ migration = is_migration_entry(entry);
page = pfn_swap_entry_to_page(entry);
}
#endif
- if (page && page_mapcount(page) == 1)
+ if (page && !migration && page_mapcount(page) == 1)
flags |= PM_MMAP_EXCLUSIVE;
for (; addr != end; addr += PAGE_SIZE) {