[PATCH v2] zsmalloc: Fix races between modifications of fullness and isolated
Andrew Yang
andrew.yang at mediatek.com
Wed Jul 26 23:29:07 PDT 2023
Since fullness and isolated share the same unsigned int,
modifications of them should be protected by the same lock.
Signed-off-by: Andrew Yang <andrew.yang at mediatek.com>
Fixes: c4549b871102 ("zsmalloc: remove zspage isolation for migration")
---
v2: Moving comment too
---
mm/zsmalloc.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 32f5bc4074df..b58f957429f0 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1777,6 +1777,7 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
{
+ struct zs_pool *pool;
struct zspage *zspage;
/*
@@ -1786,9 +1787,10 @@ static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
VM_BUG_ON_PAGE(PageIsolated(page), page);
zspage = get_zspage(page);
- migrate_write_lock(zspage);
+ pool = zspage->pool;
+ spin_lock(&pool->lock);
inc_zspage_isolation(zspage);
- migrate_write_unlock(zspage);
+ spin_unlock(&pool->lock);
return true;
}
@@ -1854,12 +1856,12 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
kunmap_atomic(s_addr);
replace_sub_page(class, zspage, newpage, page);
+ dec_zspage_isolation(zspage);
/*
* Since we complete the data copy and set up new zspage structure,
* it's okay to release the pool's lock.
*/
spin_unlock(&pool->lock);
- dec_zspage_isolation(zspage);
migrate_write_unlock(zspage);
get_page(newpage);
@@ -1876,14 +1878,16 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
static void zs_page_putback(struct page *page)
{
+ struct zs_pool *pool;
struct zspage *zspage;
VM_BUG_ON_PAGE(!PageIsolated(page), page);
zspage = get_zspage(page);
- migrate_write_lock(zspage);
+ pool = zspage->pool;
+ spin_lock(&pool->lock);
dec_zspage_isolation(zspage);
- migrate_write_unlock(zspage);
+ spin_unlock(&pool->lock);
}
static const struct movable_operations zsmalloc_mops = {
--
2.18.0
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