FAILED: patch "[PATCH] mm, slab: clean up slab->obj_exts always" failed to apply to 6.14-stable tree

The patch below does not apply to the 6.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.14.y
git checkout FETCH_HEAD
git cherry-pick -x be8250786ca94952a19ce87f98ad9906448bc9ef
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025050521-provable-extent-4108@gregkh' --subject-prefix 'PATCH 6.14.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be8250786ca94952a19ce87f98ad9906448bc9ef Mon Sep 17 00:00:00 2001
From: Zhenhua Huang <[email protected]>
Date: Mon, 21 Apr 2025 15:52:32 +0800
Subject: [PATCH] mm, slab: clean up slab->obj_exts always

When memory allocation profiling is disabled at runtime or due to an error, shutdown_mem_profiling() is called: slab->obj_exts which previously allocated remains.
It won't be cleared by unaccount_slab() because of mem_alloc_profiling_enabled() not true. It's incorrect, slab->obj_exts should always be cleaned up in unaccount_slab() to avoid following error:

[...]BUG: Bad page state in process...
..
[...]page dumped because: page still charged to cgroup

[[email protected]: fold need_slab_obj_ext() into its only user]

Fixes 21c690a349ba ("mm: introduce slabobj_ext to support slab object extensions")

Cc [email protected]

Signed-off-by Zhenhua Huang <[email protected]>

Acked-by David Rientjes <[email protected]>

Acked-by Harry Yoo <[email protected]>

Tested-by Harry Yoo <[email protected]>

Acked-by Suren Baghdasaryan <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Vlastimil Babka <[email protected]>

mm/slub.c +8 -22

index dc9e729e1d26..be8b09e09d30 100644
@@ -2028,8 +2028,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
        return 0;
 }
 
-/* Should be called only if mem_alloc_profiling_enabled() */
-static noinline void free_slab_obj_exts(struct slab *slab)
+static inline void free_slab_obj_exts(struct slab *slab)
 {
        struct slabobj_ext *obj_exts;
 

@@ -2049,18 +2048,6 @@ static noinline void free_slab_obj_exts(struct slab *slab)
        slab->obj_exts = 0;
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-       if (mem_alloc_profiling_enabled())
-               return true;
-
-       /*
-        * CONFIG_MEMCG creates vector of obj_cgroup objects conditionally
-        * inside memcg_slab_post_alloc_hook. No other users for now.
-        */
-       return false;
-}
-
 #else /* CONFIG_SLAB_OBJ_EXT */
 
 static inline void init_slab_obj_exts(struct slab *slab)

@@ -2077,11 +2064,6 @@ static inline void free_slab_obj_exts(struct slab *slab)
 {
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-       return false;
-}
-
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
 #ifdef CONFIG_MEM_ALLOC_PROFILING

@@ -2129,7 +2111,7 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 static inline void
 alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 {
-       if (need_slab_obj_ext())
+       if (mem_alloc_profiling_enabled())
                __alloc_tagging_slab_alloc_hook(s, object, flags);
 }
 

@@ -2601,8 +2583,12 @@ static __always_inline void account_slab(struct slab *slab, int order,
 static __always_inline void unaccount_slab(struct slab *slab, int order,
                                           struct kmem_cache *s)
 {
-       if (memcg_kmem_online() || need_slab_obj_ext())
-               free_slab_obj_exts(slab);
+       /*
+        * The slab object extensions should now be freed regardless of
+        * whether mem_alloc_profiling_enabled() or not because profiling
+        * might have been disabled after slab->obj_exts got allocated.
+        */
+       free_slab_obj_exts(slab);
 
        mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
                            -(PAGE_SIZE << order));

Quoted 6 lines · On Mon, May 5, 2025 at 12:55 AM <[email protected]> wrote:

The patch below does not apply to the 6.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

I'll work on the backport. Thanks!

Quoted 118 lines

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.14.y
git checkout FETCH_HEAD
git cherry-pick -x be8250786ca94952a19ce87f98ad9906448bc9ef
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025050521-provable-extent-4108@gregkh' --subject-prefix 'PATCH 6.14.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be8250786ca94952a19ce87f98ad9906448bc9ef Mon Sep 17 00:00:00 2001
From: Zhenhua Huang <[email protected]>
Date: Mon, 21 Apr 2025 15:52:32 +0800
Subject: [PATCH] mm, slab: clean up slab->obj_exts always

When memory allocation profiling is disabled at runtime or due to an error, shutdown_mem_profiling() is called: slab->obj_exts which previously allocated remains.
It won't be cleared by unaccount_slab() because of mem_alloc_profiling_enabled() not true. It's incorrect, slab->obj_exts should always be cleaned up in unaccount_slab() to avoid following error:

[...]BUG: Bad page state in process...
..
[...]page dumped because: page still charged to cgroup

[[email protected]: fold need_slab_obj_ext() into its only user]

Fixes 21c690a349ba ("mm: introduce slabobj_ext to support slab object extensions")

Cc [email protected]

Signed-off-by Zhenhua Huang <[email protected]>

Acked-by David Rientjes <[email protected]>

Acked-by Harry Yoo <[email protected]>

Tested-by Harry Yoo <[email protected]>

Acked-by Suren Baghdasaryan <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Vlastimil Babka <[email protected]>

mm/slub.c +8 -22

index dc9e729e1d26..be8b09e09d30 100644
@@ -2028,8 +2028,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
        return 0;
 }
 
-/* Should be called only if mem_alloc_profiling_enabled() */
-static noinline void free_slab_obj_exts(struct slab *slab)
+static inline void free_slab_obj_exts(struct slab *slab)
 {
        struct slabobj_ext *obj_exts;
 

@@ -2049,18 +2048,6 @@ static noinline void free_slab_obj_exts(struct slab *slab)
        slab->obj_exts = 0;
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-       if (mem_alloc_profiling_enabled())
-               return true;
-
-       /*
-        * CONFIG_MEMCG creates vector of obj_cgroup objects conditionally
-        * inside memcg_slab_post_alloc_hook. No other users for now.
-        */
-       return false;
-}
-
 #else /* CONFIG_SLAB_OBJ_EXT */
 
 static inline void init_slab_obj_exts(struct slab *slab)

@@ -2077,11 +2064,6 @@ static inline void free_slab_obj_exts(struct slab *slab)
 {
 }
 
-static inline bool need_slab_obj_ext(void)
-{
-       return false;
-}
-
 #endif /* CONFIG_SLAB_OBJ_EXT */
 
 #ifdef CONFIG_MEM_ALLOC_PROFILING

@@ -2129,7 +2111,7 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 static inline void
 alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags)
 {
-       if (need_slab_obj_ext())
+       if (mem_alloc_profiling_enabled())
                __alloc_tagging_slab_alloc_hook(s, object, flags);
 }
 

@@ -2601,8 +2583,12 @@ static __always_inline void account_slab(struct slab *slab, int order,
 static __always_inline void unaccount_slab(struct slab *slab, int order,
                                           struct kmem_cache *s)
 {
-       if (memcg_kmem_online() || need_slab_obj_ext())
-               free_slab_obj_exts(slab);
+       /*
+        * The slab object extensions should now be freed regardless of
+        * whether mem_alloc_profiling_enabled() or not because profiling
+        * might have been disabled after slab->obj_exts got allocated.
+        */
+       free_slab_obj_exts(slab);
 
        mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
                            -(PAGE_SIZE << order));