linux-kernel - Re: [PATCH] slub_kunit:fix a WARNING due to __kmalloc_cache

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Message-ID: <873ca7e7-5789-4e4c-b3aa-4331cf2b6638@suse.cz>
Date: Wed, 23 Oct 2024 10:00:48 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Pei Xiao <xiaopei01@...inos.cn>, surenb@...gle.com
Cc: akpm@...ux-foundation.org, gehao@...inos.cn, hao.ge@...ux.dev,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org, xiaopeitux@...mail.com,
 xiongxin@...inos.cn, yuzhao@...gle.com
Subject: Re: [PATCH] slub_kunit:fix a WARNING due to __kmalloc_cache_noprof
 incorretly use

On 10/23/24 08:21, Pei Xiao wrote:
> 'modprobe slub_kunit',will have a warning [1].The root cause is that
> __kmalloc_cache_noprof was directly used,which resulted in no alloc_tag
> being allocated.This caused current->alloc_tag to be null,leading to
> a warning in alloc_tag_add_check.
> 
> Let's add an alloc_hook layer to __kmalloc_cache_noprof specifically
> within lib/slub_kunit.c.
> 
> [1].
> [58162.947016] WARNING: CPU: 2 PID: 6210 at
> ./include/linux/alloc_tag.h:125 alloc_tagging_slab_alloc_hook+0x268/0x27c
> [58162.957721] Call trace:
> [58162.957919]  alloc_tagging_slab_alloc_hook+0x268/0x27c
> [58162.958286]  __kmalloc_cache_noprof+0x14c/0x344
> [58162.958615]  test_kmalloc_redzone_access+0x50/0x10c [slub_kunit]
> [58162.959045]  kunit_try_run_case+0x74/0x184 [kunit]
> [58162.959401]  kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit]
> [58162.959841]  kthread+0x10c/0x118
> [58162.960093]  ret_from_fork+0x10/0x20
> [58162.960363] ---[ end trace 0000000000000000 ]---
> 
> Signed-off-by: Pei Xiao <xiaopei01@...inos.cn>
> Fixes: a0a44d9175b3 ("mm, slab: don't wrap internal functions with alloc_hooks()")

Thanks, I'm adding the fix for test_kmalloc_redzone_access() to
slab/for-6.12-rc4/fixes as a 6.12 hotfix

> Fixes: a286da323418 ("mm/slub, kunit: Add testcase for krealloc redzone and zeroing")

This is in slab/for-next so I will just adjust the new tests in place there.

> ---
>  lib/slub_kunit.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
> index 3cd1cc667988..f11691315c2f 100644
> --- a/lib/slub_kunit.c
> +++ b/lib/slub_kunit.c
> @@ -141,7 +141,7 @@ static void test_kmalloc_redzone_access(struct kunit *test)
>  {
>  	struct kmem_cache *s = test_kmem_cache_create("TestSlub_RZ_kmalloc", 32,
>  				SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE);
> -	u8 *p = __kmalloc_cache_noprof(s, GFP_KERNEL, 18);
> +	u8 *p = alloc_hooks(__kmalloc_cache_noprof(s, GFP_KERNEL, 18));
>  
>  	kasan_disable_current();
>  
> @@ -199,7 +199,7 @@ static void test_krealloc_redzone_zeroing(struct kunit *test)
>  	struct kmem_cache *s = test_kmem_cache_create("TestSlub_krealloc", 64,
>  				SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE);
>  
> -	p = __kmalloc_cache_noprof(s, GFP_KERNEL, 48);
> +	p = alloc_hooks(__kmalloc_cache_noprof(s, GFP_KERNEL, 48));
>  	memset(p, 0xff, 48);
>  
>  	kasan_disable_current();