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mm/rmap: Turn page_referenced() into folio_referenced()
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Both its callers pass a page which was previously on an LRU list,
so were passing a folio by definition.  Use the type system to enforce
that and remove a few calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Matthew Wilcox (Oracle) committed Mar 21, 2022
1 parent dcc5d33 commit b3ac041
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Showing 4 changed files with 50 additions and 46 deletions.
4 changes: 2 additions & 2 deletions include/linux/rmap.h
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Original file line number Diff line number Diff line change
Expand Up @@ -190,7 +190,7 @@ static inline void page_dup_rmap(struct page *page, bool compound)
/*
* Called from mm/vmscan.c to handle paging out
*/
int page_referenced(struct page *, int is_locked,
int folio_referenced(struct folio *, int is_locked,
struct mem_cgroup *memcg, unsigned long *vm_flags);

void try_to_migrate(struct page *page, enum ttu_flags flags);
Expand Down Expand Up @@ -301,7 +301,7 @@ void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
#define anon_vma_prepare(vma) (0)
#define anon_vma_link(vma) do {} while (0)

static inline int page_referenced(struct page *page, int is_locked,
static inline int folio_referenced(struct folio *folio, int is_locked,
struct mem_cgroup *memcg,
unsigned long *vm_flags)
{
Expand Down
2 changes: 1 addition & 1 deletion mm/page_idle.c
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,7 @@ static bool page_idle_clear_pte_refs_one(struct page *page,
/*
* We cleared the referenced bit in a mapping to this page. To
* avoid interference with page reclaim, mark it young so that
* page_referenced() will return > 0.
* folio_referenced() will return > 0.
*/
folio_set_young(folio);
}
Expand Down
70 changes: 35 additions & 35 deletions mm/rmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -789,29 +789,30 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
return pmd;
}

struct page_referenced_arg {
struct folio_referenced_arg {
int mapcount;
int referenced;
unsigned long vm_flags;
struct mem_cgroup *memcg;
};
/*
* arg: page_referenced_arg will be passed
* arg: folio_referenced_arg will be passed
*/
static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
static bool folio_referenced_one(struct page *page, struct vm_area_struct *vma,
unsigned long address, void *arg)
{
struct page_referenced_arg *pra = arg;
DEFINE_PAGE_VMA_WALK(pvmw, page, vma, address, 0);
struct folio *folio = page_folio(page);
struct folio_referenced_arg *pra = arg;
DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
int referenced = 0;

while (page_vma_mapped_walk(&pvmw)) {
address = pvmw.address;

if ((vma->vm_flags & VM_LOCKED) &&
(!PageTransCompound(page) || !pvmw.pte)) {
(!folio_test_large(folio) || !pvmw.pte)) {
/* Restore the mlock which got missed */
mlock_vma_page(page, vma, !pvmw.pte);
mlock_vma_folio(folio, vma, !pvmw.pte);
page_vma_mapped_walk_done(&pvmw);
pra->vm_flags |= VM_LOCKED;
return false; /* To break the loop */
Expand All @@ -823,10 +824,10 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
/*
* Don't treat a reference through
* a sequentially read mapping as such.
* If the page has been used in another mapping,
* If the folio has been used in another mapping,
* we will catch it; if this other mapping is
* already gone, the unmap path will have set
* PG_referenced or activated the page.
* the referenced flag or activated the folio.
*/
if (likely(!(vma->vm_flags & VM_SEQ_READ)))
referenced++;
Expand All @@ -836,16 +837,16 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
pvmw.pmd))
referenced++;
} else {
/* unexpected pmd-mapped page? */
/* unexpected pmd-mapped folio? */
WARN_ON_ONCE(1);
}

pra->mapcount--;
}

if (referenced)
clear_page_idle(page);
if (test_and_clear_page_young(page))
folio_clear_idle(folio);
if (folio_test_clear_young(folio))
referenced++;

if (referenced) {
Expand All @@ -859,9 +860,9 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
return true;
}

static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
{
struct page_referenced_arg *pra = arg;
struct folio_referenced_arg *pra = arg;
struct mem_cgroup *memcg = pra->memcg;

if (!mm_match_cgroup(vma->vm_mm, memcg))
Expand All @@ -871,27 +872,26 @@ static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
}

/**
* page_referenced - test if the page was referenced
* @page: the page to test
* @is_locked: caller holds lock on the page
* folio_referenced() - Test if the folio was referenced.
* @folio: The folio to test.
* @is_locked: Caller holds lock on the folio.
* @memcg: target memory cgroup
* @vm_flags: collect encountered vma->vm_flags who actually referenced the page
* @vm_flags: A combination of all the vma->vm_flags which referenced the folio.
*
* Quick test_and_clear_referenced for all mappings to a page,
* returns the number of ptes which referenced the page.
* Quick test_and_clear_referenced for all mappings of a folio,
*
* Return: The number of mappings which referenced the folio.
*/
int page_referenced(struct page *page,
int is_locked,
struct mem_cgroup *memcg,
unsigned long *vm_flags)
int folio_referenced(struct folio *folio, int is_locked,
struct mem_cgroup *memcg, unsigned long *vm_flags)
{
int we_locked = 0;
struct page_referenced_arg pra = {
.mapcount = total_mapcount(page),
struct folio_referenced_arg pra = {
.mapcount = folio_mapcount(folio),
.memcg = memcg,
};
struct rmap_walk_control rwc = {
.rmap_one = page_referenced_one,
.rmap_one = folio_referenced_one,
.arg = (void *)&pra,
.anon_lock = page_lock_anon_vma_read,
};
Expand All @@ -900,11 +900,11 @@ int page_referenced(struct page *page,
if (!pra.mapcount)
return 0;

if (!page_rmapping(page))
if (!folio_raw_mapping(folio))
return 0;

if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
we_locked = trylock_page(page);
if (!is_locked && (!folio_test_anon(folio) || folio_test_ksm(folio))) {
we_locked = folio_trylock(folio);
if (!we_locked)
return 1;
}
Expand All @@ -915,14 +915,14 @@ int page_referenced(struct page *page,
* cgroups
*/
if (memcg) {
rwc.invalid_vma = invalid_page_referenced_vma;
rwc.invalid_vma = invalid_folio_referenced_vma;
}

rmap_walk(page, &rwc);
rmap_walk(&folio->page, &rwc);
*vm_flags = pra.vm_flags;

if (we_locked)
unlock_page(page);
folio_unlock(folio);

return pra.referenced;
}
Expand Down Expand Up @@ -1052,8 +1052,8 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
/*
* Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
* simultaneously, so a concurrent reader (eg page_referenced()'s
* PageAnon()) will not see one without the other.
* simultaneously, so a concurrent reader (eg folio_referenced()'s
* folio_test_anon()) will not see one without the other.
*/
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
}
Expand Down
20 changes: 12 additions & 8 deletions mm/vmscan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1386,11 +1386,12 @@ enum page_references {
static enum page_references page_check_references(struct page *page,
struct scan_control *sc)
{
struct folio *folio = page_folio(page);
int referenced_ptes, referenced_page;
unsigned long vm_flags;

referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
&vm_flags);
referenced_ptes = folio_referenced(folio, 1, sc->target_mem_cgroup,
&vm_flags);
referenced_page = TestClearPageReferenced(page);

/*
Expand Down Expand Up @@ -2490,7 +2491,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
*
* If the pages are mostly unmapped, the processing is fast and it is
* appropriate to hold lru_lock across the whole operation. But if
* the pages are mapped, the processing is slow (page_referenced()), so
* the pages are mapped, the processing is slow (folio_referenced()), so
* we should drop lru_lock around each page. It's impossible to balance
* this, so instead we remove the pages from the LRU while processing them.
* It is safe to rely on PG_active against the non-LRU pages in here because
Expand All @@ -2510,7 +2511,6 @@ static void shrink_active_list(unsigned long nr_to_scan,
LIST_HEAD(l_hold); /* The pages which were snipped off */
LIST_HEAD(l_active);
LIST_HEAD(l_inactive);
struct page *page;
unsigned nr_deactivate, nr_activate;
unsigned nr_rotated = 0;
int file = is_file_lru(lru);
Expand All @@ -2532,9 +2532,13 @@ static void shrink_active_list(unsigned long nr_to_scan,
spin_unlock_irq(&lruvec->lru_lock);

while (!list_empty(&l_hold)) {
struct folio *folio;
struct page *page;

cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
folio = lru_to_folio(&l_hold);
list_del(&folio->lru);
page = &folio->page;

if (unlikely(!page_evictable(page))) {
putback_lru_page(page);
Expand All @@ -2549,8 +2553,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
}
}

if (page_referenced(page, 0, sc->target_mem_cgroup,
&vm_flags)) {
if (folio_referenced(folio, 0, sc->target_mem_cgroup,
&vm_flags)) {
/*
* Identify referenced, file-backed active pages and
* give them one more trip around the active list. So
Expand Down

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