linux-kernel - [PATCH 1/3] mm/zsmalloc: fix migrate_write_lock() when !CONFIG

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Date: Mon, 19 Feb 2024 13:33:51 +0000
From: Chengming Zhou <zhouchengming@...edance.com>
To: nphamcs@...il.com, yosryahmed@...gle.com, Sergey Senozhatsky <senozhatsky@...omium.org>,
 Minchan Kim <minchan@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, hannes@...xchg.org
Cc: linux-mm@...ck.org, Chengming Zhou <zhouchengming@...edance.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] mm/zsmalloc: fix migrate_write_lock() when !CONFIG_COMPACTION

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@...edance.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