[PATCH v3 1/4] mm: change to return bool for folio_isolate_lru()
From: Baolin Wang
Date: Wed Feb 15 2023 - 05:39:59 EST
Now the folio_isolate_lru() did not return a boolean value to indicate
isolation success or not, however below code checking the return value
can make people think that it was a boolean success/failure thing, which
makes people easy to make mistakes (see the fix patch[1]).
if (folio_isolate_lru(folio))
continue;
Thus it's better to check the negative error value expilictly returned by
folio_isolate_lru(), which makes code more clear per Linus's suggestion[2].
Moreover Matthew suggested we can convert the isolation functions to return
a boolean[3], since most users did not care about the negative error value,
and can also remove the confusing of checking return value.
So this patch converts the folio_isolate_lru() to return a boolean value,
which means return 'true' to indicate the folio isolation is successful,
and 'false' means a failure to isolation. Meanwhile changing all users'
logic of checking the isolation state.
No functional changes intended.
[1] https://lore.kernel.org/all/20230131063206.28820-1-Kuan-Ying.Lee@xxxxxxxxxxxx/T/#u
[2] https://lore.kernel.org/all/CAHk-=wiBrY+O-4=2mrbVyxR+hOqfdJ=Do6xoucfJ9_5az01L4Q@xxxxxxxxxxxxxx/
[3] https://lore.kernel.org/all/Y+sTFqwMNAjDvxw3@xxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: SeongJae Park <sj@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/damon/paddr.c | 2 +-
mm/folio-compat.c | 8 +++++++-
mm/gup.c | 2 +-
mm/internal.h | 2 +-
mm/khugepaged.c | 2 +-
mm/madvise.c | 4 ++--
mm/mempolicy.c | 2 +-
mm/vmscan.c | 10 +++++-----
8 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index b4df9b9bcc0a..607bb69e526c 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -246,7 +246,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
folio_clear_referenced(folio);
folio_test_clear_young(folio);
- if (folio_isolate_lru(folio)) {
+ if (!folio_isolate_lru(folio)) {
folio_put(folio);
continue;
}
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 18c48b557926..540373cf904e 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -115,9 +115,15 @@ EXPORT_SYMBOL(grab_cache_page_write_begin);
int isolate_lru_page(struct page *page)
{
+ bool ret;
+
if (WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"))
return -EBUSY;
- return folio_isolate_lru((struct folio *)page);
+ ret = folio_isolate_lru((struct folio *)page);
+ if (ret)
+ return 0;
+
+ return -EBUSY;
}
void putback_lru_page(struct page *page)
diff --git a/mm/gup.c b/mm/gup.c
index b0885f70579c..eab18ba045db 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1939,7 +1939,7 @@ static unsigned long collect_longterm_unpinnable_pages(
drain_allow = false;
}
- if (folio_isolate_lru(folio))
+ if (!folio_isolate_lru(folio))
continue;
list_add_tail(&folio->lru, movable_page_list);
diff --git a/mm/internal.h b/mm/internal.h
index dfb37e94e140..8645e8496537 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -188,7 +188,7 @@ pgprot_t __init early_memremap_pgprot_adjust(resource_size_t phys_addr,
* in mm/vmscan.c:
*/
int isolate_lru_page(struct page *page);
-int folio_isolate_lru(struct folio *folio);
+bool folio_isolate_lru(struct folio *folio);
void putback_lru_page(struct page *page);
void folio_putback_lru(struct folio *folio);
extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a5d32231bfad..cee659cfa3c1 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2047,7 +2047,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
goto out_unlock;
}
- if (folio_isolate_lru(folio)) {
+ if (!folio_isolate_lru(folio)) {
result = SCAN_DEL_PAGE_LRU;
goto out_unlock;
}
diff --git a/mm/madvise.c b/mm/madvise.c
index 5a5a687d03c2..c2202f51e9dd 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -406,7 +406,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
folio_clear_referenced(folio);
folio_test_clear_young(folio);
if (pageout) {
- if (!folio_isolate_lru(folio)) {
+ if (folio_isolate_lru(folio)) {
if (folio_test_unevictable(folio))
folio_putback_lru(folio);
else
@@ -500,7 +500,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
folio_clear_referenced(folio);
folio_test_clear_young(folio);
if (pageout) {
- if (!folio_isolate_lru(folio)) {
+ if (folio_isolate_lru(folio)) {
if (folio_test_unevictable(folio))
folio_putback_lru(folio);
else
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0919c7a719d4..2751bc3310fd 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1033,7 +1033,7 @@ static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
* expensive, so check the estimated mapcount of the folio instead.
*/
if ((flags & MPOL_MF_MOVE_ALL) || folio_estimated_sharers(folio) == 1) {
- if (!folio_isolate_lru(folio)) {
+ if (folio_isolate_lru(folio)) {
list_add_tail(&folio->lru, foliolist);
node_stat_mod_folio(folio,
NR_ISOLATED_ANON + folio_is_file_lru(folio),
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 34535bbd4fe9..7658b40df947 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2337,12 +2337,12 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
* (2) The lru_lock must not be held.
* (3) Interrupts must be enabled.
*
- * Return: 0 if the folio was removed from an LRU list.
- * -EBUSY if the folio was not on an LRU list.
+ * Return: true if the folio was removed from an LRU list.
+ * false if the folio was not on an LRU list.
*/
-int folio_isolate_lru(struct folio *folio)
+bool folio_isolate_lru(struct folio *folio)
{
- int ret = -EBUSY;
+ bool ret = false;
VM_BUG_ON_FOLIO(!folio_ref_count(folio), folio);
@@ -2353,7 +2353,7 @@ int folio_isolate_lru(struct folio *folio)
lruvec = folio_lruvec_lock_irq(folio);
lruvec_del_folio(lruvec, folio);
unlock_page_lruvec_irq(lruvec);
- ret = 0;
+ ret = true;
}
return ret;
--
2.27.0