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mm/huge_memory: Convert __split_huge_pmd() to take a folio

Browse source 
Convert split_huge_pmd_address() at the same time since it only passes
the folio through, and its two callers already have a folio on hand.
Removes numerous calls to compound_head() and removes an assumption
that a page cannot be larger than a PMD.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-01-21 10:44:52 -05:00
parent b3ac04132c
commit af28a988b3
3 changed files with 31 additions and 29 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
include/linux/huge_mm.h
View file

@ -194,7 +194,7 @@ static inline int split_huge_page(struct page *page)
void deferred_split_huge_page(struct page *page);
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long address, bool freeze, struct page *page);
unsigned long address, bool freeze, struct folio *folio);
#define split_huge_pmd(__vma, __pmd, __address) \
do { \
@ -207,7 +207,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
bool freeze, struct page *page);
bool freeze, struct folio *folio);
void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
unsigned long address);
@ -406,9 +406,9 @@ static inline void deferred_split_huge_page(struct page *page) {}
do { } while (0)
static inline void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long address, bool freeze, struct page *page) {}
unsigned long address, bool freeze, struct folio *folio) {}
static inline void split_huge_pmd_address(struct vm_area_struct *vma,
unsigned long address, bool freeze, struct page *page) {}
unsigned long address, bool freeze, struct folio *folio) {}
#define split_huge_pud(__vma, __pmd, __address) \
do { } while (0)

46
mm/huge_memory.c
View file

@ -2113,11 +2113,11 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
}
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long address, bool freeze, struct page *page)
unsigned long address, bool freeze, struct folio *folio)
{
spinlock_t *ptl;
struct mmu_notifier_range range;
bool do_unlock_page = false;
bool do_unlock_folio = false;
pmd_t _pmd;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
@ -2127,20 +2127,20 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
ptl = pmd_lock(vma->vm_mm, pmd);
/*
* If caller asks to setup a migration entries, we need a page to check
* pmd against. Otherwise we can end up replacing wrong page.
* If caller asks to setup a migration entry, we need a folio to check
* pmd against. Otherwise we can end up replacing wrong folio.
*/
VM_BUG_ON(freeze && !page);
if (page) {
VM_WARN_ON_ONCE(!PageLocked(page));
if (page != pmd_page(*pmd))
VM_BUG_ON(freeze && !folio);
if (folio) {
VM_WARN_ON_ONCE(!folio_test_locked(folio));
if (folio != page_folio(pmd_page(*pmd)))
goto out;
}
repeat:
if (pmd_trans_huge(*pmd)) {
if (!page) {
page = pmd_page(*pmd);
if (!folio) {
folio = page_folio(pmd_page(*pmd));
/*
* An anonymous page must be locked, to ensure that a
* concurrent reuse_swap_page() sees stable mapcount;
@ -2148,22 +2148,22 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
* and page lock must not be taken when zap_pmd_range()
* calls __split_huge_pmd() while i_mmap_lock is held.
*/
if (PageAnon(page)) {
if (unlikely(!trylock_page(page))) {
get_page(page);
if (folio_test_anon(folio)) {
if (unlikely(!folio_trylock(folio))) {
folio_get(folio);
_pmd = *pmd;
spin_unlock(ptl);
lock_page(page);
folio_lock(folio);
spin_lock(ptl);
if (unlikely(!pmd_same(*pmd, _pmd))) {
unlock_page(page);
put_page(page);
page = NULL;
folio_unlock(folio);
folio_put(folio);
folio = NULL;
goto repeat;
}
put_page(page);
folio_put(folio);
}
do_unlock_page = true;
do_unlock_folio = true;
}
}
} else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
@ -2171,8 +2171,8 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
__split_huge_pmd_locked(vma, pmd, range.start, freeze);
out:
spin_unlock(ptl);
if (do_unlock_page)
unlock_page(page);
if (do_unlock_folio)
folio_unlock(folio);
/*
* No need to double call mmu_notifier->invalidate_range() callback.
* They are 3 cases to consider inside __split_huge_pmd_locked():
@ -2190,7 +2190,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
}
void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
bool freeze, struct page *page)
bool freeze, struct folio *folio)
{
pgd_t *pgd;
p4d_t *p4d;
@ -2211,7 +2211,7 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
pmd = pmd_offset(pud, address);
__split_huge_pmd(vma, pmd, address, freeze, page);
__split_huge_pmd(vma, pmd, address, freeze, folio);
}
static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)

6
mm/rmap.c
View file

@ -1410,6 +1410,7 @@ void page_remove_rmap(struct page *page,
static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
unsigned long address, void *arg)
{
struct folio *folio = page_folio(page);
struct mm_struct *mm = vma->vm_mm;
DEFINE_PAGE_VMA_WALK(pvmw, page, vma, address, 0);
pte_t pteval;
@ -1428,7 +1429,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
pvmw.flags = PVMW_SYNC;
if (flags & TTU_SPLIT_HUGE_PMD)
split_huge_pmd_address(vma, address, false, page);
split_huge_pmd_address(vma, address, false, folio);
/*
* For THP, we have to assume the worse case ie pmd for invalidation.
@ -1700,6 +1701,7 @@ void try_to_unmap(struct page *page, enum ttu_flags flags)
static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
unsigned long address, void *arg)
{
struct folio *folio = page_folio(page);
struct mm_struct *mm = vma->vm_mm;
DEFINE_PAGE_VMA_WALK(pvmw, page, vma, address, 0);
pte_t pteval;
@ -1722,7 +1724,7 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
* TTU_SPLIT_HUGE_PMD and it wants to freeze.
*/
if (flags & TTU_SPLIT_HUGE_PMD)
split_huge_pmd_address(vma, address, true, page);
split_huge_pmd_address(vma, address, true, folio);
/*
* For THP, we have to assume the worse case ie pmd for invalidation.