* [PATCH V2 1/2] mm/slab: allow freeing kmalloc_nolock()'d objects using kfree[_rcu]()
2026-02-10 4:46 [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]() Harry Yoo
@ 2026-02-10 4:46 ` Harry Yoo
2026-02-10 4:46 ` [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags Harry Yoo
2026-02-10 14:08 ` [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]() Vlastimil Babka
2 siblings, 0 replies; 6+ messages in thread
From: Harry Yoo @ 2026-02-10 4:46 UTC (permalink / raw)
To: Andrew Morton, Vlastimil Babka
Cc: Christoph Lameter, David Rientjes, Roman Gushchin, Hao Li,
Alexei Starovoitov, Catalin Marinas, Uladzislau Rezki,
Suren Baghdasaryan, linux-mm, Harry Yoo
Slab objects that are allocated with kmalloc_nolock() must be freed
using kfree_nolock() because only a subset of alloc hooks are called,
since kmalloc_nolock() can't spin on a lock during allocation.
This imposes a limitation: such objects cannot be freed with kfree_rcu(),
forcing users to work around this limitation by calling call_rcu()
with a callback that frees the object using kfree_nolock().
Remove this limitation by teaching kmemleak to gracefully ignore cases
when kmemleak_free() or kmemleak_ignore() is called without a prior
kmemleak_alloc().
Unlike kmemleak, kfence already handles this case, because,
due to its design, only a subset of allocations are served from kfence.
With this change, kfree() and kfree_rcu() can be used to free objects
that are allocated using kmalloc_nolock().
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
---
include/linux/rcupdate.h | 4 ++--
mm/kmemleak.c | 22 ++++++++++------------
mm/slub.c | 21 ++++++++++++++++++++-
3 files changed, 32 insertions(+), 15 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index c5b30054cd01..72ba681360ad 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -1076,8 +1076,8 @@ static inline void rcu_read_unlock_migrate(void)
* either fall back to use of call_rcu() or rearrange the structure to
* position the rcu_head structure into the first 4096 bytes.
*
- * The object to be freed can be allocated either by kmalloc() or
- * kmem_cache_alloc().
+ * The object to be freed can be allocated either by kmalloc(),
+ * kmalloc_nolock(), or kmem_cache_alloc().
*
* Note that the allowable offset might decrease in the future.
*
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 1ac56ceb29b6..95ad827fcd69 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -837,13 +837,12 @@ static void delete_object_full(unsigned long ptr, unsigned int objflags)
struct kmemleak_object *object;
object = find_and_remove_object(ptr, 0, objflags);
- if (!object) {
-#ifdef DEBUG
- kmemleak_warn("Freeing unknown object at 0x%08lx\n",
- ptr);
-#endif
+ if (!object)
+ /*
+ * kmalloc_nolock() -> kfree() calls kmemleak_free()
+ * without kmemleak_alloc().
+ */
return;
- }
__delete_object(object);
}
@@ -926,13 +925,12 @@ static void paint_ptr(unsigned long ptr, int color, unsigned int objflags)
struct kmemleak_object *object;
object = __find_and_get_object(ptr, 0, objflags);
- if (!object) {
- kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
- ptr,
- (color == KMEMLEAK_GREY) ? "Grey" :
- (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
+ if (!object)
+ /*
+ * kmalloc_nolock() -> kfree_rcu() calls kmemleak_ignore()
+ * without kmemleak_alloc().
+ */
return;
- }
paint_it(object, color);
put_object(object);
}
diff --git a/mm/slub.c b/mm/slub.c
index 11a99bd06ac7..63b03fd62ca7 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2584,6 +2584,24 @@ struct rcu_delayed_free {
* Returns true if freeing of the object can proceed, false if its reuse
* was delayed by CONFIG_SLUB_RCU_DEBUG or KASAN quarantine, or it was returned
* to KFENCE.
+ *
+ * For objects allocated via kmalloc_nolock(), only a subset of alloc hooks
+ * are invoked, so some free hooks must handle asymmetric hook calls.
+ *
+ * Alloc hooks called for kmalloc_nolock():
+ * - kmsan_slab_alloc()
+ * - kasan_slab_alloc()
+ * - memcg_slab_post_alloc_hook()
+ * - alloc_tagging_slab_alloc_hook()
+ *
+ * Free hooks that must handle missing corresponding alloc hooks:
+ * - kmemleak_free_recursive()
+ * - kfence_free()
+ *
+ * Free hooks that have no alloc hook counterpart, and thus safe to call:
+ * - debug_check_no_locks_freed()
+ * - debug_check_no_obj_freed()
+ * - __kcsan_check_access()
*/
static __always_inline
bool slab_free_hook(struct kmem_cache *s, void *x, bool init,
@@ -6368,7 +6386,7 @@ void kvfree_rcu_cb(struct rcu_head *head)
/**
* kfree - free previously allocated memory
- * @object: pointer returned by kmalloc() or kmem_cache_alloc()
+ * @object: pointer returned by kmalloc(), kmalloc_nolock(), or kmem_cache_alloc()
*
* If @object is NULL, no operation is performed.
*/
@@ -6387,6 +6405,7 @@ void kfree(const void *object)
page = virt_to_page(object);
slab = page_slab(page);
if (!slab) {
+ /* kmalloc_nolock() doesn't support large kmalloc */
free_large_kmalloc(page, (void *)object);
return;
}
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags
2026-02-10 4:46 [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]() Harry Yoo
2026-02-10 4:46 ` [PATCH V2 1/2] mm/slab: allow freeing kmalloc_nolock()'d objects using kfree[_rcu]() Harry Yoo
@ 2026-02-10 4:46 ` Harry Yoo
2026-02-10 8:57 ` Hao Li
2026-02-10 14:08 ` [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]() Vlastimil Babka
2 siblings, 1 reply; 6+ messages in thread
From: Harry Yoo @ 2026-02-10 4:46 UTC (permalink / raw)
To: Andrew Morton, Vlastimil Babka
Cc: Christoph Lameter, David Rientjes, Roman Gushchin, Hao Li,
Alexei Starovoitov, Catalin Marinas, Uladzislau Rezki,
Suren Baghdasaryan, linux-mm, Harry Yoo
OBJEXTS_NOSPIN_ALLOC was used to remember whether a slabobj_ext vector
was allocated via kmalloc_nolock(), so that free_slab_obj_exts() could
call kfree_nolock() instead of kfree().
Now that kfree() supports freeing kmalloc_nolock() objects, this flag is
no longer needed. Instead, pass the allow_spin parameter down to
free_slab_obj_exts() to determine whether kfree_nolock() or kfree()
should be called in the free path, and free one bit in
enum objext_flags.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
---
include/linux/memcontrol.h | 3 +--
mm/slub.c | 18 ++++++++----------
2 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0651865a4564..bb789ec4a2a2 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -359,8 +359,7 @@ enum objext_flags {
* MEMCG_DATA_OBJEXTS.
*/
OBJEXTS_ALLOC_FAIL = __OBJEXTS_ALLOC_FAIL,
- /* slabobj_ext vector allocated with kmalloc_nolock() */
- OBJEXTS_NOSPIN_ALLOC = __FIRST_OBJEXT_FLAG,
+ __OBJEXTS_FLAG_UNUSED = __FIRST_OBJEXT_FLAG,
/* the next bit after the last actual flag */
__NR_OBJEXTS_FLAGS = (__FIRST_OBJEXT_FLAG << 1),
};
diff --git a/mm/slub.c b/mm/slub.c
index 63b03fd62ca7..a73a80b33ff9 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2189,8 +2189,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
virt_to_slab(vec)->slab_cache == s);
new_exts = (unsigned long)vec;
- if (unlikely(!allow_spin))
- new_exts |= OBJEXTS_NOSPIN_ALLOC;
#ifdef CONFIG_MEMCG
new_exts |= MEMCG_DATA_OBJEXTS;
#endif
@@ -2228,7 +2226,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
return 0;
}
-static inline void free_slab_obj_exts(struct slab *slab)
+static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin)
{
struct slabobj_ext *obj_exts;
@@ -2256,10 +2254,10 @@ static inline void free_slab_obj_exts(struct slab *slab)
* the extension for obj_exts is expected to be NULL.
*/
mark_objexts_empty(obj_exts);
- if (unlikely(READ_ONCE(slab->obj_exts) & OBJEXTS_NOSPIN_ALLOC))
- kfree_nolock(obj_exts);
- else
+ if (allow_spin)
kfree(obj_exts);
+ else
+ kfree_nolock(obj_exts);
slab->obj_exts = 0;
}
@@ -2323,7 +2321,7 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
return 0;
}
-static inline void free_slab_obj_exts(struct slab *slab)
+static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin)
{
}
@@ -3387,14 +3385,14 @@ 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)
+ struct kmem_cache *s, bool allow_spin)
{
/*
* 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);
+ free_slab_obj_exts(slab, allow_spin);
mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
-(PAGE_SIZE << order));
@@ -3498,7 +3496,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab, bool allow_spin
page->mapping = NULL;
__ClearPageSlab(page);
mm_account_reclaimed_pages(pages);
- unaccount_slab(slab, order, s);
+ unaccount_slab(slab, order, s, allow_spin);
if (allow_spin)
free_frozen_pages(page, order);
else
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags
2026-02-10 4:46 ` [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags Harry Yoo
@ 2026-02-10 8:57 ` Hao Li
2026-02-10 10:32 ` Harry Yoo
0 siblings, 1 reply; 6+ messages in thread
From: Hao Li @ 2026-02-10 8:57 UTC (permalink / raw)
To: Harry Yoo
Cc: Andrew Morton, Vlastimil Babka, Christoph Lameter,
David Rientjes, Roman Gushchin, Alexei Starovoitov,
Catalin Marinas, Uladzislau Rezki, Suren Baghdasaryan, linux-mm
On Tue, Feb 10, 2026 at 01:46:42PM +0900, Harry Yoo wrote:
> OBJEXTS_NOSPIN_ALLOC was used to remember whether a slabobj_ext vector
> was allocated via kmalloc_nolock(), so that free_slab_obj_exts() could
> call kfree_nolock() instead of kfree().
>
> Now that kfree() supports freeing kmalloc_nolock() objects, this flag is
> no longer needed. Instead, pass the allow_spin parameter down to
> free_slab_obj_exts() to determine whether kfree_nolock() or kfree()
> should be called in the free path, and free one bit in
> enum objext_flags.
>
> Acked-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
> ---
> include/linux/memcontrol.h | 3 +--
> mm/slub.c | 18 ++++++++----------
> 2 files changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 0651865a4564..bb789ec4a2a2 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -359,8 +359,7 @@ enum objext_flags {
> * MEMCG_DATA_OBJEXTS.
> */
> OBJEXTS_ALLOC_FAIL = __OBJEXTS_ALLOC_FAIL,
> - /* slabobj_ext vector allocated with kmalloc_nolock() */
> - OBJEXTS_NOSPIN_ALLOC = __FIRST_OBJEXT_FLAG,
> + __OBJEXTS_FLAG_UNUSED = __FIRST_OBJEXT_FLAG,
> /* the next bit after the last actual flag */
> __NR_OBJEXTS_FLAGS = (__FIRST_OBJEXT_FLAG << 1),
> };
> diff --git a/mm/slub.c b/mm/slub.c
> index 63b03fd62ca7..a73a80b33ff9 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2189,8 +2189,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> virt_to_slab(vec)->slab_cache == s);
>
> new_exts = (unsigned long)vec;
> - if (unlikely(!allow_spin))
> - new_exts |= OBJEXTS_NOSPIN_ALLOC;
> #ifdef CONFIG_MEMCG
> new_exts |= MEMCG_DATA_OBJEXTS;
> #endif
> @@ -2228,7 +2226,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> return 0;
> }
>
> -static inline void free_slab_obj_exts(struct slab *slab)
> +static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin)
> {
> struct slabobj_ext *obj_exts;
>
> @@ -2256,10 +2254,10 @@ static inline void free_slab_obj_exts(struct slab *slab)
> * the extension for obj_exts is expected to be NULL.
> */
> mark_objexts_empty(obj_exts);
> - if (unlikely(READ_ONCE(slab->obj_exts) & OBJEXTS_NOSPIN_ALLOC))
> - kfree_nolock(obj_exts);
> - else
> + if (allow_spin)
> kfree(obj_exts);
> + else
> + kfree_nolock(obj_exts);
Looks good to me.
One small observation from my side: at first glance I briefly wondered if we
could ever allocate in an allow_spin=true context but free in an
allow_spin=false context, potentially resulting in a kmalloc() -> kfree_nolock()
mismatch.
After taking a closer look, the only case where "free_new_slab_nolock() -> ...
-> free_slab_obj_exts()" runs with allow_spin=false is along the "___slab_alloc
-> alloc_single_from_new_slab()/alloc_from_new_slab()" path. In that scenario,
alloc_slab_obj_exts() is also called under allow_spin=false and uses
kmalloc_nolock(), so the allocation/free paths remain consistent. So "kmalloc()
-> kfree_nolock()" case can't happen, and the code looks solid to me!
Reviewed-by: Hao Li <hao.li@linux.dev>
> slab->obj_exts = 0;
> }
>
> @@ -2323,7 +2321,7 @@ static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> return 0;
> }
>
> -static inline void free_slab_obj_exts(struct slab *slab)
> +static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin)
> {
> }
>
> @@ -3387,14 +3385,14 @@ 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)
> + struct kmem_cache *s, bool allow_spin)
> {
> /*
> * 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);
> + free_slab_obj_exts(slab, allow_spin);
>
> mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
> -(PAGE_SIZE << order));
> @@ -3498,7 +3496,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab, bool allow_spin
> page->mapping = NULL;
> __ClearPageSlab(page);
> mm_account_reclaimed_pages(pages);
> - unaccount_slab(slab, order, s);
> + unaccount_slab(slab, order, s, allow_spin);
> if (allow_spin)
> free_frozen_pages(page, order);
> else
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags
2026-02-10 8:57 ` Hao Li
@ 2026-02-10 10:32 ` Harry Yoo
0 siblings, 0 replies; 6+ messages in thread
From: Harry Yoo @ 2026-02-10 10:32 UTC (permalink / raw)
To: Hao Li
Cc: Andrew Morton, Vlastimil Babka, Christoph Lameter,
David Rientjes, Roman Gushchin, Alexei Starovoitov,
Catalin Marinas, Uladzislau Rezki, Suren Baghdasaryan, linux-mm
On Tue, Feb 10, 2026 at 04:57:42PM +0800, Hao Li wrote:
> On Tue, Feb 10, 2026 at 01:46:42PM +0900, Harry Yoo wrote:
> > OBJEXTS_NOSPIN_ALLOC was used to remember whether a slabobj_ext vector
> > was allocated via kmalloc_nolock(), so that free_slab_obj_exts() could
> > call kfree_nolock() instead of kfree().
> >
> > Now that kfree() supports freeing kmalloc_nolock() objects, this flag is
> > no longer needed. Instead, pass the allow_spin parameter down to
> > free_slab_obj_exts() to determine whether kfree_nolock() or kfree()
> > should be called in the free path, and free one bit in
> > enum objext_flags.
> >
> > Acked-by: Alexei Starovoitov <ast@kernel.org>
> > Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
> > ---
> > include/linux/memcontrol.h | 3 +--
> > mm/slub.c | 18 ++++++++----------
> > 2 files changed, 9 insertions(+), 12 deletions(-)
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index 0651865a4564..bb789ec4a2a2 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -359,8 +359,7 @@ enum objext_flags {
> > * MEMCG_DATA_OBJEXTS.
> > */
> > OBJEXTS_ALLOC_FAIL = __OBJEXTS_ALLOC_FAIL,
> > - /* slabobj_ext vector allocated with kmalloc_nolock() */
> > - OBJEXTS_NOSPIN_ALLOC = __FIRST_OBJEXT_FLAG,
> > + __OBJEXTS_FLAG_UNUSED = __FIRST_OBJEXT_FLAG,
> > /* the next bit after the last actual flag */
> > __NR_OBJEXTS_FLAGS = (__FIRST_OBJEXT_FLAG << 1),
> > };
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 63b03fd62ca7..a73a80b33ff9 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -2189,8 +2189,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> > virt_to_slab(vec)->slab_cache == s);
> >
> > new_exts = (unsigned long)vec;
> > - if (unlikely(!allow_spin))
> > - new_exts |= OBJEXTS_NOSPIN_ALLOC;
> > #ifdef CONFIG_MEMCG
> > new_exts |= MEMCG_DATA_OBJEXTS;
> > #endif
> > @@ -2228,7 +2226,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> > return 0;
> > }
> >
> > -static inline void free_slab_obj_exts(struct slab *slab)
> > +static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin)
> > {
> > struct slabobj_ext *obj_exts;
> >
> > @@ -2256,10 +2254,10 @@ static inline void free_slab_obj_exts(struct slab *slab)
> > * the extension for obj_exts is expected to be NULL.
> > */
> > mark_objexts_empty(obj_exts);
> > - if (unlikely(READ_ONCE(slab->obj_exts) & OBJEXTS_NOSPIN_ALLOC))
> > - kfree_nolock(obj_exts);
> > - else
> > + if (allow_spin)
> > kfree(obj_exts);
> > + else
> > + kfree_nolock(obj_exts);
>
> Looks good to me.
>
> One small observation from my side: at first glance I briefly wondered if we
> could ever allocate in an allow_spin=true context but free in an
> allow_spin=false context, potentially resulting in a kmalloc() -> kfree_nolock()
> mismatch.
Right, kmalloc() -> kfree_nolock() is not supported and must be avoided.
> After taking a closer look, the only case where "free_new_slab_nolock() -> ...
> -> free_slab_obj_exts()" runs with allow_spin=false is along the "___slab_alloc
> -> alloc_single_from_new_slab()/alloc_from_new_slab()" path.
Right, this is when trylock failed after allocating new slab.
> In that scenario, alloc_slab_obj_exts() is also called under allow_spin=false
> and uses kmalloc_nolock(), so the allocation/free paths remain consistent.
> So "kmalloc() -> kfree_nolock()" case can't happen,
> and the code looks solid to me!
Nice analysis, thanks!
Yeah, for this reason, we should not free slabs that are allocated
with allow_spin == true, when allow_spin is false.
kfree_nolock() avoids this by deferring frees in the slowpath.
If someone is tempated to rework kfree_nolock() slowpath, he or she
should be careful :)
> Reviewed-by: Hao Li <hao.li@linux.dev>
Thanks for review, Hao!
--
Cheers,
Harry / Hyeonggon
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]()
2026-02-10 4:46 [PATCH V2 0/2] mm/slab: support kmalloc_nolock() -> kfree[_rcu]() Harry Yoo
2026-02-10 4:46 ` [PATCH V2 1/2] mm/slab: allow freeing kmalloc_nolock()'d objects using kfree[_rcu]() Harry Yoo
2026-02-10 4:46 ` [PATCH V2 2/2] mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags Harry Yoo
@ 2026-02-10 14:08 ` Vlastimil Babka
2 siblings, 0 replies; 6+ messages in thread
From: Vlastimil Babka @ 2026-02-10 14:08 UTC (permalink / raw)
To: Harry Yoo, Andrew Morton
Cc: Christoph Lameter, David Rientjes, Roman Gushchin, Hao Li,
Alexei Starovoitov, Catalin Marinas, Uladzislau Rezki,
Suren Baghdasaryan, linux-mm
On 2/10/26 05:46, Harry Yoo wrote:
> This is separated from the RFC version of "k[v]free_rcu() improvements"
> series [1], as these changes are relatively small and beneficial for BPF
> because it enables the bpf code to use kfree_rcu() instead of
> call_rcu() + kfree_nolock().
>
> Patch 1 allows kfree() and kfree_rcu() to be used with objects that are
> allocated from kmalloc_nolock().
>
> Patch 2 is a cleanup that frees a bit used to record whether obj_exts
> was allocated using kmalloc_nolock() or kmalloc(), since now both cases
> can be freed with kfree().
>
> [1] https://lore.kernel.org/linux-mm/20260206093410.160622-1-harry.yoo@oracle.com
Thanks, added to slab/for-next
> v1 -> v2:
> - Added Catalin's Reviewed-by tag on patch 1, and Alexei's Acked-by tag
> on patch 2 that I forgot to add. Thanks!
>
> - Fix calling kfree() in free_slab_obj_exts() and alloc_slab_obj_exts()
> when !allow_spin. Pass allow_spin parameter down to free_slab_obj_exts().
>
> V1: https://lore.kernel.org/linux-mm/20260209121013.50475-1-harry.yoo@oracle.com
>
> Harry Yoo (2):
> mm/slab: allow freeing kmalloc_nolock()'d objects using kfree[_rcu]()
> mm/slab: drop the OBJEXTS_NOSPIN_ALLOC flag from enum objext_flags
>
> include/linux/memcontrol.h | 3 +--
> include/linux/rcupdate.h | 4 ++--
> mm/kmemleak.c | 22 ++++++++++-----------
> mm/slub.c | 39 +++++++++++++++++++++++++++-----------
> 4 files changed, 41 insertions(+), 27 deletions(-)
>
>
> base-commit: f6ed7e47c1fc78e78c9bfeb668b1ad9ba5c58120
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