[PATCH] zsmalloc: return -EAGAIN for zspage migration lock contention

[Hui Zhu]

From: teawater <zhuhui@xxxxxxxxxx>

movable_operations::migrate_page() should return -EAGAIN for temporary
migration failures so the migration core can retry. Other negative
errors are treated as permanent failures.

zs_page_migrate() currently returns -EINVAL when zspage_write_trylock()
fails. That path reflects transient lock contention, not invalid input.
Returning -EINVAL misclassifies the failure and can reduce migration
success under contention.

Return -EAGAIN in this path.

Fixes: e27af3f9360e ("zsmalloc: sleepable zspage reader-lock")
Signed-off-by: teawater <zhuhui@xxxxxxxxxx>
---
 mm/zsmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 2c1430bf8d57..1d26eda7f50c 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1727,7 +1727,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	if (!zspage_write_trylock(zspage)) {
 		spin_unlock(&class->lock);
 		write_unlock(&pool->lock);
-		return -EINVAL;
+		return -EAGAIN;
 	}
 
 	/* We're committed, tell the world that this is a Zsmalloc page. */
-- 
2.43.0