[PATCH RESEND 1/3] mm/zsmalloc: fix migrate_write_lock() when !CONFIG_COMPACTION

Chengming Zhou
2024-02-20T11:37:29Z

From: Chengming Zhou <zhouchengming@bytedance.com>

migrate_write_lock() is a empty function when !CONFIG_COMPACTION, in
which case zs_compact() can be triggered from shrinker reclaim context.
(Maybe it's better to rename it to zs_shrink()?)

And zspage map object users rely on this migrate_read_lock() so object
won't be migrated elsewhere.

Fix it by always implementing the migrate_write_lock() related functions.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
mm/zsmalloc.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c937635e0ad1..64d5533fa5d8 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -278,18 +278,15 @@ static bool ZsHugePage(struct zspage *zspage)
static void migrate_lock_init(struct zspage *zspage);
static void migrate_read_lock(struct zspage *zspage);
static void migrate_read_unlock(struct zspage *zspage);
-
-#ifdef CONFIG_COMPACTION
static void migrate_write_lock(struct zspage *zspage);
static void migrate_write_lock_nested(struct zspage *zspage);
static void migrate_write_unlock(struct zspage *zspage);
+
+#ifdef CONFIG_COMPACTION
static void kick_deferred_free(struct zs_pool *pool);
static void init_deferred_free(struct zs_pool *pool);
static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
#else
-static void migrate_write_lock(struct zspage *zspage) {}
-static void migrate_write_lock_nested(struct zspage *zspage) {}
-static void migrate_write_unlock(struct zspage *zspage) {}
static void kick_deferred_free(struct zs_pool *pool) {}
static void init_deferred_free(struct zs_pool *pool) {}
static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
@@ -1725,7 +1722,6 @@ static void migrate_read_unlock(struct zspage *zspage) __releases(&zspage->lock)
read_unlock(&zspage->lock);
}

-#ifdef CONFIG_COMPACTION
static void migrate_write_lock(struct zspage *zspage)
{
write_lock(&zspage->lock);
@@ -1741,6 +1737,7 @@ static void migrate_write_unlock(struct zspage *zspage)
write_unlock(&zspage->lock);
}

+#ifdef CONFIG_COMPACTION
/* Number of isolated subpage for *page migration* in this zspage */
static void inc_zspage_isolation(struct zspage *zspage)
{

--
b4 0.10.1