Commit 9de4f22a authored by Huang Ying's avatar Huang Ying Committed by Linus Torvalds

mm: code cleanup for MADV_FREE

Some comments for MADV_FREE is revised and added to help people understand
the MADV_FREE code, especially the page flag, PG_swapbacked.  This makes
page_is_file_cache() isn't consistent with its comments.  So the function
is renamed to page_is_file_lru() to make them consistent again.  All these
are put in one patch as one logical change.
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Suggested-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Acked-by: default avatarMichal Hocko <mhocko@kernel.org>
Acked-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7a9547fd
......@@ -6,19 +6,20 @@
#include <linux/swap.h>
/**
* page_is_file_cache - should the page be on a file LRU or anon LRU?
* page_is_file_lru - should the page be on a file LRU or anon LRU?
* @page: the page to test
*
* Returns 1 if @page is page cache page backed by a regular filesystem,
* or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed.
* Used by functions that manipulate the LRU lists, to sort a page
* onto the right LRU list.
* Returns 1 if @page is a regular filesystem backed page cache page or a lazily
* freed anonymous page (e.g. via MADV_FREE). Returns 0 if @page is a normal
* anonymous page, a tmpfs page or otherwise ram or swap backed page. Used by
* functions that manipulate the LRU lists, to sort a page onto the right LRU
* list.
*
* We would like to get this info without a page flag, but the state
* needs to survive until the page is last deleted from the LRU, which
* could be as far down as __page_cache_release.
*/
static inline int page_is_file_cache(struct page *page)
static inline int page_is_file_lru(struct page *page)
{
return !PageSwapBacked(page);
}
......@@ -75,7 +76,7 @@ static __always_inline void del_page_from_lru_list(struct page *page,
*/
static inline enum lru_list page_lru_base_type(struct page *page)
{
if (page_is_file_cache(page))
if (page_is_file_lru(page))
return LRU_INACTIVE_FILE;
return LRU_INACTIVE_ANON;
}
......
......@@ -63,6 +63,11 @@
* page_waitqueue(page) is a wait queue of all tasks waiting for the page
* to become unlocked.
*
* PG_swapbacked is set when a page uses swap as a backing storage. This are
* usually PageAnon or shmem pages but please note that even anonymous pages
* might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
* a result of MADV_FREE).
*
* PG_uptodate tells whether the page's contents is valid. When a read
* completes, the page becomes uptodate, unless a disk I/O error happened.
*
......
......@@ -323,7 +323,7 @@ TRACE_EVENT(mm_vmscan_writepage,
TP_fast_assign(
__entry->pfn = page_to_pfn(page);
__entry->reclaim_flags = trace_reclaim_flags(
page_is_file_cache(page));
page_is_file_lru(page));
),
TP_printk("page=%p pfn=%lu flags=%s",
......
......@@ -989,7 +989,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
/* Successfully isolated */
del_page_from_lru_list(page, lruvec, page_lru(page));
mod_node_page_state(page_pgdat(page),
NR_ISOLATED_ANON + page_is_file_cache(page),
NR_ISOLATED_ANON + page_is_file_lru(page),
hpage_nr_pages(page));
isolate_success:
......
......@@ -1677,7 +1677,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
list_add_tail(&head->lru, &cma_page_list);
mod_node_page_state(page_pgdat(head),
NR_ISOLATED_ANON +
page_is_file_cache(head),
page_is_file_lru(head),
hpage_nr_pages(head));
}
}
......
......@@ -511,7 +511,7 @@ void __khugepaged_exit(struct mm_struct *mm)
static void release_pte_page(struct page *page)
{
dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page));
dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_lru(page));
unlock_page(page);
putback_lru_page(page);
}
......@@ -611,7 +611,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
goto out;
}
inc_node_page_state(page,
NR_ISOLATED_ANON + page_is_file_cache(page));
NR_ISOLATED_ANON + page_is_file_lru(page));
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(PageLRU(page), page);
......
......@@ -1810,7 +1810,7 @@ static int __soft_offline_page(struct page *page, int flags)
*/
if (!__PageMovable(page))
inc_node_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
page_is_file_lru(page));
list_add(&page->lru, &pagelist);
ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
MIGRATE_SYNC, MR_MEMORY_FAILURE);
......
......@@ -1317,7 +1317,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
list_add_tail(&page->lru, &source);
if (!__PageMovable(page))
inc_node_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
page_is_file_lru(page));
} else {
pr_warn("failed to isolate pfn %lx\n", pfn);
......
......@@ -1022,7 +1022,7 @@ static int migrate_page_add(struct page *page, struct list_head *pagelist,
if (!isolate_lru_page(head)) {
list_add_tail(&head->lru, pagelist);
mod_node_page_state(page_pgdat(head),
NR_ISOLATED_ANON + page_is_file_cache(head),
NR_ISOLATED_ANON + page_is_file_lru(head),
hpage_nr_pages(head));
} else if (flags & MPOL_MF_STRICT) {
/*
......
......@@ -193,7 +193,7 @@ void putback_movable_pages(struct list_head *l)
put_page(page);
} else {
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
page_is_file_cache(page), -hpage_nr_pages(page));
page_is_file_lru(page), -hpage_nr_pages(page));
putback_lru_page(page);
}
}
......@@ -1219,7 +1219,7 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
*/
if (likely(!__PageMovable(page)))
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
page_is_file_cache(page), -hpage_nr_pages(page));
page_is_file_lru(page), -hpage_nr_pages(page));
}
/*
......@@ -1592,7 +1592,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
err = 1;
list_add_tail(&head->lru, pagelist);
mod_node_page_state(page_pgdat(head),
NR_ISOLATED_ANON + page_is_file_cache(head),
NR_ISOLATED_ANON + page_is_file_lru(head),
hpage_nr_pages(head));
}
out_putpage:
......@@ -1955,7 +1955,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
return 0;
}
page_lru = page_is_file_cache(page);
page_lru = page_is_file_lru(page);
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru,
hpage_nr_pages(page));
......@@ -1991,7 +1991,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
* Don't migrate file pages that are mapped in multiple processes
* with execute permissions as they are probably shared libraries.
*/
if (page_mapcount(page) != 1 && page_is_file_cache(page) &&
if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
(vma->vm_flags & VM_EXEC))
goto out;
......@@ -1999,7 +1999,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
* Also do not migrate dirty pages as not all filesystems can move
* dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
*/
if (page_is_file_cache(page) && PageDirty(page))
if (page_is_file_lru(page) && PageDirty(page))
goto out;
isolated = numamigrate_isolate_page(pgdat, page);
......@@ -2014,7 +2014,7 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
if (!list_empty(&migratepages)) {
list_del(&page->lru);
dec_node_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
page_is_file_lru(page));
putback_lru_page(page);
}
isolated = 0;
......@@ -2044,7 +2044,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
pg_data_t *pgdat = NODE_DATA(node);
int isolated = 0;
struct page *new_page = NULL;
int page_lru = page_is_file_cache(page);
int page_lru = page_is_file_lru(page);
unsigned long start = address & HPAGE_PMD_MASK;
new_page = alloc_pages_node(node,
......
......@@ -98,7 +98,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
* it cannot move them all from MIGRATE_ASYNC
* context.
*/
if (page_is_file_cache(page) && PageDirty(page))
if (page_is_file_lru(page) && PageDirty(page))
continue;
/*
......
......@@ -276,7 +276,7 @@ static void __activate_page(struct page *page, struct lruvec *lruvec,
void *arg)
{
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
int file = page_is_file_cache(page);
int file = page_is_file_lru(page);
int lru = page_lru_base_type(page);
del_page_from_lru_list(page, lruvec, lru);
......@@ -394,7 +394,7 @@ void mark_page_accessed(struct page *page)
else
__lru_cache_activate_page(page);
ClearPageReferenced(page);
if (page_is_file_cache(page))
if (page_is_file_lru(page))
workingset_activation(page);
}
if (page_is_idle(page))
......@@ -515,7 +515,7 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
return;
active = PageActive(page);
file = page_is_file_cache(page);
file = page_is_file_lru(page);
lru = page_lru_base_type(page);
del_page_from_lru_list(page, lruvec, lru + active);
......@@ -548,7 +548,7 @@ static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
int file = page_is_file_cache(page);
int file = page_is_file_lru(page);
int lru = page_lru_base_type(page);
del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
......@@ -573,9 +573,9 @@ static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
ClearPageActive(page);
ClearPageReferenced(page);
/*
* lazyfree pages are clean anonymous pages. They have
* SwapBacked flag cleared to distinguish normal anonymous
* pages
* Lazyfree pages are clean anonymous pages. They have
* PG_swapbacked flag cleared, to distinguish them from normal
* anonymous pages
*/
ClearPageSwapBacked(page);
add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
......@@ -962,7 +962,7 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
if (page_evictable(page)) {
lru = page_lru(page);
update_page_reclaim_stat(lruvec, page_is_file_cache(page),
update_page_reclaim_stat(lruvec, page_is_file_lru(page),
PageActive(page));
if (was_unevictable)
count_vm_event(UNEVICTABLE_PGRESCUED);
......
......@@ -919,7 +919,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
* exceptional entries and shadow exceptional entries in the
* same address_space.
*/
if (reclaimed && page_is_file_cache(page) &&
if (reclaimed && page_is_file_lru(page) &&
!mapping_exiting(mapping) && !dax_mapping(mapping))
shadow = workingset_eviction(page, target_memcg);
__delete_from_page_cache(page, shadow);
......@@ -1043,7 +1043,7 @@ static void page_check_dirty_writeback(struct page *page,
* Anonymous pages are not handled by flushers and must be written
* from reclaim context. Do not stall reclaim based on them
*/
if (!page_is_file_cache(page) ||
if (!page_is_file_lru(page) ||
(PageAnon(page) && !PageSwapBacked(page))) {
*dirty = false;
*writeback = false;
......@@ -1315,7 +1315,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* the rest of the LRU for clean pages and see
* the same dirty pages again (PageReclaim).
*/
if (page_is_file_cache(page) &&
if (page_is_file_lru(page) &&
(!current_is_kswapd() || !PageReclaim(page) ||
!test_bit(PGDAT_DIRTY, &pgdat->flags))) {
/*
......@@ -1459,7 +1459,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
try_to_free_swap(page);
VM_BUG_ON_PAGE(PageActive(page), page);
if (!PageMlocked(page)) {
int type = page_is_file_cache(page);
int type = page_is_file_lru(page);
SetPageActive(page);
stat->nr_activate[type] += nr_pages;
count_memcg_page_event(page, PGACTIVATE);
......@@ -1497,7 +1497,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
LIST_HEAD(clean_pages);
list_for_each_entry_safe(page, next, page_list, lru) {
if (page_is_file_cache(page) && !PageDirty(page) &&
if (page_is_file_lru(page) && !PageDirty(page) &&
!__PageMovable(page) && !PageUnevictable(page)) {
ClearPageActive(page);
list_move(&page->lru, &clean_pages);
......@@ -2053,7 +2053,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
* IO, plus JVM can create lots of anon VM_EXEC pages,
* so we ignore them here.
*/
if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
if ((vm_flags & VM_EXEC) && page_is_file_lru(page)) {
list_add(&page->lru, &l_active);
continue;
}
......
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