[PATCH] slab: Add allow_spin check to eliminate kmemleak warnings

[ranxiaokai627]

From: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx>

In slab_post_alloc_hook(), kmemleak check is skipped when
gfpflags_allow_spinning() returns false since commit 13d872ade8be
("slab: Introduce kmalloc_nolock() and kfree_nolock().").
Therefore, unconditionally calling kmemleak_not_leak() in
alloc_slab_obj_exts() would trigger the following warning:

kmemleak: Trying to color unknown object at 0xffff8881057f5000 as Grey
Call Trace:
 alloc_slab_obj_exts+0x1b5/0x370
 __alloc_tagging_slab_alloc_hook+0x9f/0x2d0
 __kmalloc_cache_noprof+0x1c4/0x5c0
 __set_page_owner+0x10d/0x1c0
 post_alloc_hook+0x84/0xf0
 get_page_from_freelist+0x73b/0x1380
 __alloc_frozen_pages_noprof+0x110/0x2c0
 alloc_pages_mpol+0x44/0x140
 alloc_slab_page+0xac/0x150
 allocate_slab+0x78/0x3a0
 ___slab_alloc+0x76b/0xed0
 __slab_alloc.constprop.0+0x5a/0xb0

Add the allow_spin check in alloc_slab_obj_exts() to
eliminate the above warning.

Fixes: 13d872ade8be ("slab: Introduce kmalloc_nolock() and kfree_nolock().")
Signed-off-by: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx>
---
 mm/slub.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 09cbe580842c..a76275f4870a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2145,7 +2145,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 		return 0;
 	}
 
-	kmemleak_not_leak(vec);
+	if (allow_spin)
+		kmemleak_not_leak(vec);
 	return 0;
 }
 
-- 
2.25.1