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mm/slab: replace __GFP_NO_OBJ_EXT with SLAB_ALLOC_NO_RECURSE for sheaves

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Finish the switch away from __GFP_NO_OBJ_EXT by replacing it with
SLAB_ALLOC_NO_RECURSE when allocating empty sheaves. Pass alloc_flags to
[__]alloc_empty_sheaf(). Callers that can't be part of a recursive
kmalloc() chain simply pass SLAB_ALLOC_DEFAULT. Use kmalloc_flags()
instead of kzalloc() for allocating the sheaf.

With that we can finalize the removal the __GFP_NO_OBJ_EXT handling from
obj_ext allocations as well, leaving only SLAB_ALLOC_NO_RECURSE in
place.

This leaves __GFP_NO_OBJ_EXT with no users in slab, so stop allowing the
flag in kmalloc_nolock().

Link: https://patch.msgid.link/20260610-slab_alloc_flags-v2-16-7190909db118@kernel.org
Reviewed-by: Hao Li <hao.li@linux.dev>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
This commit is contained in:
Vlastimil Babka (SUSE) 2026-06-11 18:24:06 +02:00
parent 3022263960
commit 71553a6067
2 changed files with 20 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/slab.h
View File

@ -1039,9 +1039,9 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in
/**
* kmalloc_nolock - Allocate an object of given size from any context.
* @size: size to allocate
* @gfp_flags: GFP flags. Only __GFP_ACCOUNT, __GFP_ZERO, __GFP_NO_OBJ_EXT
* allowed. Also __GFP_NOWARN and __GFP_NOMEMALLOC are allowed but added
* internally thus not necessary.
* @gfp_flags: GFP flags. Only __GFP_ACCOUNT and __GFP_ZERO allowed. Also
* __GFP_NOWARN and __GFP_NOMEMALLOC are allowed but added internally thus not
* necessary.
* @node: node number of the target node.
*
* Return: pointer to the new object or NULL in case of error.

34
mm/slub.c
View File

@ -2172,7 +2172,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
gfp &= ~OBJCGS_CLEAR_MASK;
/* Prevent recursive extension vector allocation */
gfp |= __GFP_NO_OBJ_EXT;
alloc_flags |= SLAB_ALLOC_NO_RECURSE;
alloc_flags &= ~SLAB_ALLOC_NEW_SLAB;
@ -2378,7 +2377,7 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags,
if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
return;
if (alloc_flags & SLAB_ALLOC_NO_RECURSE || flags & __GFP_NO_OBJ_EXT)
if (alloc_flags & SLAB_ALLOC_NO_RECURSE)
return;
slab = virt_to_slab(object);
@ -2763,7 +2762,7 @@ static inline void *setup_object(struct kmem_cache *s, void *object)
}
static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
unsigned int capacity)
unsigned int alloc_flags, unsigned int capacity)
{
struct slab_sheaf *sheaf;
size_t sheaf_size;
@ -2774,10 +2773,10 @@ static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
* bucket)
*/
if (s->flags & SLAB_KMALLOC)
gfp |= __GFP_NO_OBJ_EXT;
alloc_flags |= SLAB_ALLOC_NO_RECURSE;
sheaf_size = struct_size(sheaf, objects, capacity);
sheaf = kzalloc(sheaf_size, gfp);
sheaf = kmalloc_flags(sheaf_size, gfp | __GFP_ZERO, alloc_flags, NUMA_NO_NODE);
if (unlikely(!sheaf))
return NULL;
@ -2790,20 +2789,20 @@ static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
}
static inline struct slab_sheaf *alloc_empty_sheaf(struct kmem_cache *s,
gfp_t gfp)
gfp_t gfp, unsigned int alloc_flags)
{
if (gfp & __GFP_NO_OBJ_EXT)
if (alloc_flags & SLAB_ALLOC_NO_RECURSE)
return NULL;
gfp &= ~OBJCGS_CLEAR_MASK;
return __alloc_empty_sheaf(s, gfp, s->sheaf_capacity);
return __alloc_empty_sheaf(s, gfp, alloc_flags, s->sheaf_capacity);
}
static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf)
{
/*
* If the sheaf was created with __GFP_NO_OBJ_EXT flag then its
* If the sheaf was created with SLAB_ALLOC_NO_RECURSE flag then its
* corresponding extension is NULL and alloc_tag_sub() will throw a
* warning, therefore replace NULL with CODETAG_EMPTY to indicate
* that the extension for this sheaf is expected to be NULL.
@ -4695,7 +4694,7 @@ __pcs_replace_empty_main(struct kmem_cache *s, struct slub_percpu_sheaves *pcs,
return NULL;
if (!empty) {
empty = alloc_empty_sheaf(s, gfp);
empty = alloc_empty_sheaf(s, gfp, alloc_flags);
if (!empty)
return NULL;
}
@ -5068,7 +5067,7 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
if (unlikely(size > s->sheaf_capacity)) {
sheaf = __alloc_empty_sheaf(s, gfp, size);
sheaf = __alloc_empty_sheaf(s, gfp, SLAB_ALLOC_DEFAULT, size);
if (!sheaf)
return NULL;
@ -5113,7 +5112,7 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
if (!sheaf)
sheaf = alloc_empty_sheaf(s, gfp);
sheaf = alloc_empty_sheaf(s, gfp, SLAB_ALLOC_DEFAULT);
if (sheaf) {
sheaf->capacity = s->sheaf_capacity;
@ -5398,7 +5397,7 @@ static void *__kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_f
VM_WARN_ON_ONCE(alloc_flags_allow_spinning(ac->alloc_flags));
VM_WARN_ON_ONCE(gfp_flags & ~(__GFP_ACCOUNT | __GFP_ZERO |
__GFP_NO_OBJ_EXT | __GFP_NOWARN | __GFP_NOMEMALLOC));
__GFP_NOWARN | __GFP_NOMEMALLOC));
gfp_flags |= __GFP_NOWARN | __GFP_NOMEMALLOC;
@ -5913,7 +5912,7 @@ __pcs_replace_full_main(struct kmem_cache *s, struct slub_percpu_sheaves *pcs,
if (!allow_spin)
return NULL;
empty = alloc_empty_sheaf(s, GFP_NOWAIT);
empty = alloc_empty_sheaf(s, GFP_NOWAIT, SLAB_ALLOC_DEFAULT);
if (empty)
goto got_empty;
@ -6097,7 +6096,7 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj)
local_unlock(&s->cpu_sheaves->lock);
empty = alloc_empty_sheaf(s, GFP_NOWAIT);
empty = alloc_empty_sheaf(s, GFP_NOWAIT, SLAB_ALLOC_DEFAULT);
if (!empty)
goto fail;
@ -7642,7 +7641,7 @@ static int init_percpu_sheaves(struct kmem_cache *s)
if (!s->sheaf_capacity)
pcs->main = &bootstrap_sheaf;
else
pcs->main = alloc_empty_sheaf(s, GFP_KERNEL);
pcs->main = alloc_empty_sheaf(s, GFP_KERNEL, SLAB_ALLOC_DEFAULT);
if (!pcs->main)
return -ENOMEM;
@ -8508,7 +8507,8 @@ static void __init bootstrap_cache_sheaves(struct kmem_cache *s)
pcs = per_cpu_ptr(s->cpu_sheaves, cpu);
pcs->main = __alloc_empty_sheaf(s, GFP_KERNEL, capacity);
pcs->main = __alloc_empty_sheaf(s, GFP_KERNEL,
SLAB_ALLOC_DEFAULT, capacity);
if (!pcs->main) {
failed = true;