[PATCH -V6 19/21] swap: Support PMD swap mapping in common path

Huang Ying
2018-10-10T07:28:28Z

Original code is only for PMD migration entry, it is revised to
support PMD swap mapping.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
---
fs/proc/task_mmu.c | 12 +++++-------
mm/gup.c | 36 ++++++++++++++++++++++++------------
mm/huge_memory.c | 7 ++++---
mm/mempolicy.c | 2 +-
4 files changed, 34 insertions(+), 23 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 0995a84c78dc..befac96b42d9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -984,7 +984,7 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma,
pmd = pmd_clear_soft_dirty(pmd);

set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
- } else if (is_migration_entry(pmd_to_swp_entry(pmd))) {
+ } else if (is_swap_pmd(pmd)) {
pmd = pmd_swp_clear_soft_dirty(pmd);
set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
}
@@ -1314,9 +1314,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
if (pm->show_pfn)
frame = pmd_pfn(pmd) +
((addr & ~PMD_MASK) >> PAGE_SHIFT);
- }
-#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
- else if (is_swap_pmd(pmd)) {
+ } else if (IS_ENABLED(CONFIG_HAVE_PMD_SWAP_ENTRY) &&
+ is_swap_pmd(pmd)) {
swp_entry_t entry = pmd_to_swp_entry(pmd);
unsigned long offset;

@@ -1329,10 +1328,9 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
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);
+ if (is_pmd_migration_entry(pmd))
+ page = migration_entry_to_page(entry);
}
-#endif

if (page && page_mapcount(page) == 1)
flags |= PM_MMAP_EXCLUSIVE;
diff --git a/mm/gup.c b/mm/gup.c
index 08eb350e0f35..17fd850aa2cc 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -216,6 +216,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
spinlock_t *ptl;
struct page *page;
struct mm_struct *mm = vma->vm_mm;
+ swp_entry_t entry;

pmd = pmd_offset(pudp, address);
/*
@@ -243,18 +244,22 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
if (!pmd_present(pmdval)) {
if (likely(!(flags & FOLL_MIGRATION)))
return no_page_table(vma, flags);
- VM_BUG_ON(thp_migration_supported() &&
- !is_pmd_migration_entry(pmdval));
- if (is_pmd_migration_entry(pmdval))
+ entry = pmd_to_swp_entry(pmdval);
+ if (thp_migration_supported() && is_migration_entry(entry)) {
pmd_migration_entry_wait(mm, pmd);
- pmdval = READ_ONCE(*pmd);
- /*
- * MADV_DONTNEED may convert the pmd to null because
- * mmap_sem is held in read mode
- */
- if (pmd_none(pmdval))
+ pmdval = READ_ONCE(*pmd);
+ /*
+ * MADV_DONTNEED may convert the pmd to null because
+ * mmap_sem is held in read mode
+ */
+ if (pmd_none(pmdval))
+ return no_page_table(vma, flags);
+ goto retry;
+ }
+ if (IS_ENABLED(CONFIG_THP_SWAP) && !non_swap_entry(entry))
return no_page_table(vma, flags);
- goto retry;
+ WARN_ON(1);
+ return no_page_table(vma, flags);
}
if (pmd_devmap(pmdval)) {
ptl = pmd_lock(mm, pmd);
@@ -276,11 +281,18 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
return no_page_table(vma, flags);
}
if (unlikely(!pmd_present(*pmd))) {
+ entry = pmd_to_swp_entry(*pmd);
spin_unlock(ptl);
if (likely(!(flags & FOLL_MIGRATION)))
return no_page_table(vma, flags);
- pmd_migration_entry_wait(mm, pmd);
- goto retry_locked;
+ if (thp_migration_supported() && is_migration_entry(entry)) {
+ pmd_migration_entry_wait(mm, pmd);
+ goto retry_locked;
+ }
+ if (IS_ENABLED(CONFIG_THP_SWAP) && !non_swap_entry(entry))
+ return no_page_table(vma, flags);
+ WARN_ON(1);
+ return no_page_table(vma, flags);
}
if (unlikely(!pmd_trans_huge(*pmd))) {
spin_unlock(ptl);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b9c766683ee1..abefc50b08b7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2133,7 +2133,7 @@ static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
static pmd_t move_soft_dirty_pmd(pmd_t pmd)
{
#ifdef CONFIG_MEM_SOFT_DIRTY
- if (unlikely(is_pmd_migration_entry(pmd)))
+ if (unlikely(is_swap_pmd(pmd)))
pmd = pmd_swp_mksoft_dirty(pmd);
else if (pmd_present(pmd))
pmd = pmd_mksoft_dirty(pmd);
@@ -2219,11 +2219,12 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
preserve_write = prot_numa && pmd_write(*pmd);
ret = 1;

-#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+#if defined(CONFIG_ARCH_ENABLE_THP_MIGRATION) || defined(CONFIG_THP_SWAP)
if (is_swap_pmd(*pmd)) {
swp_entry_t entry = pmd_to_swp_entry(*pmd);

- VM_BUG_ON(!is_pmd_migration_entry(*pmd));
+ VM_BUG_ON(!IS_ENABLED(CONFIG_THP_SWAP) &&
+ !is_migration_entry(entry));
if (is_write_migration_entry(entry)) {
pmd_t newpmd;
/*
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5837a067124d..7a5c1d2faea2 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -436,7 +436,7 @@ static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
struct queue_pages *qp = walk->private;
unsigned long flags;

- if (unlikely(is_pmd_migration_entry(*pmd))) {
+ if (unlikely(is_swap_pmd(*pmd))) {
ret = 1;
goto unlock;
}
--
2.16.4