linux-kernel - [PATCH 5.10 61/95] mm, slub: fix incorrect memcg slab count for bulk free

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Message-Id: <20211025191005.770461024@linuxfoundation.org>
Date:   Mon, 25 Oct 2021 21:14:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miaohe Lin <linmiaohe@...wei.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Bharata B Rao <bharata@...ux.ibm.com>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Faiyaz Mohammed <faiyazm@...eaurora.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Pekka Enberg <penberg@...nel.org>,
        Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.10 61/95] mm, slub: fix incorrect memcg slab count for bulk free

From: Miaohe Lin <linmiaohe@...wei.com>

commit 3ddd60268c24bcac9d744404cc277e9dc52fe6b6 upstream.

kmem_cache_free_bulk() will call memcg_slab_free_hook() for all objects
when doing bulk free.  So we shouldn't call memcg_slab_free_hook() again
for bulk free to avoid incorrect memcg slab count.

Link: https://lkml.kernel.org/r/20210916123920.48704-6-linmiaohe@huawei.com
Fixes: d1b2cf6cb84a ("mm: memcg/slab: uncharge during kmem_cache_free_bulk()")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrey Konovalov <andreyknvl@...il.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Bharata B Rao <bharata@...ux.ibm.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Faiyaz Mohammed <faiyazm@...eaurora.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Pekka Enberg <penberg@...nel.org>
Cc: Roman Gushchin <guro@...com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/slub.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3100,7 +3100,9 @@ static __always_inline void do_slab_free
 	struct kmem_cache_cpu *c;
 	unsigned long tid;
 
-	memcg_slab_free_hook(s, &head, 1);
+	/* memcg_slab_free_hook() is already called for bulk free. */
+	if (!tail)
+		memcg_slab_free_hook(s, &head, 1);
 redo:
 	/*
 	 * Determine the currently cpus per cpu slab.