With alloc_flags usage in slab, we can replace __GFP_NO_OBJ_EXT with an alloc flag that prevents kmalloc recursion. For that we need a version of kmalloc() that takes alloc_flags and use it in places that perform these potentially recursive kmalloc allocations (of sheaves or obj_ext arrays). Add this function, named kmalloc_flags(). Right now it's only useful for these nested allocations, so it doesn't need to optimize build-time constant sizes like kmalloc() or kmalloc_buckets. Since we need it to support both normal and non-spinning kmalloc_nolock() context through the SLAB_ALLOC_NOLOCK flag, split out most of the special _kmalloc_nolock_noprof() implementation to __kmalloc_nolock_noprof() that takes a slab_alloc_context, and make _kmalloc_nolock_noprof() a simple tail calling wrapper with the proper context. kmalloc_flags() can thus determine whether to call __kmalloc_nolock_noprof() or __do_kmalloc_node(), based on the given alloc_flags. Link: https://patch.msgid.link/20260610-slab_alloc_flags-v2-14-7190909db118@kernel.org Reviewed-by: Hao Li Reviewed-by: Suren Baghdasaryan Signed-off-by: Vlastimil Babka (SUSE) --- mm/slab.h | 13 +++++++++++++ mm/slub.c | 55 +++++++++++++++++++++++++++++++++++++++++++------------ 2 files changed, 56 insertions(+), 12 deletions(-) diff --git a/mm/slab.h b/mm/slab.h index d86203131f58..482b8e0fe797 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -11,6 +11,7 @@ #include #include #include +#include /* * Internal slab definitions @@ -26,6 +27,18 @@ static inline bool alloc_flags_allow_spinning(const unsigned int alloc_flags) return !(alloc_flags & SLAB_ALLOC_NOLOCK); } +void *__kmalloc_flags_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t flags, + unsigned int alloc_flags, int node) + __assume_kmalloc_alignment __alloc_size(1); + +static __always_inline __alloc_size(1) void *_kmalloc_flags_noprof(size_t size, + gfp_t flags, unsigned int alloc_flags, int node, kmalloc_token_t token) +{ + return __kmalloc_flags_noprof(PASS_TOKEN_PARAMS(size, token), flags, alloc_flags, node); +} +#define kmalloc_flags_noprof(...) _kmalloc_flags_noprof(__VA_ARGS__, __kmalloc_token(__VA_ARGS__)) +#define kmalloc_flags(...) alloc_hooks(kmalloc_flags_noprof(__VA_ARGS__)) + #ifdef CONFIG_64BIT # ifdef system_has_cmpxchg128 # define system_has_freelist_aba() system_has_cmpxchg128() diff --git a/mm/slub.c b/mm/slub.c index 8769083bec81..383d39a22561 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5385,19 +5385,14 @@ void *__kmalloc_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t flags) } EXPORT_SYMBOL(__kmalloc_noprof); -void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, int node) +static void *__kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, + int node, const struct slab_alloc_context *ac) { - size_t orig_size = size; - unsigned int alloc_flags = SLAB_ALLOC_NOLOCK; struct kmem_cache *s; bool can_retry = true; void *ret; - const struct slab_alloc_context ac = { - .caller_addr = _RET_IP_, - .orig_size = orig_size, - .alloc_flags = alloc_flags, - }; + 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)); @@ -5434,7 +5429,7 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in */ return NULL; - ret = alloc_from_pcs(s, gfp_flags, alloc_flags, node); + ret = alloc_from_pcs(s, gfp_flags, ac->alloc_flags, node); if (ret) goto success; @@ -5444,7 +5439,7 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in * kfence_alloc. Hence call __slab_alloc_node() (at most twice) * and slab_post_alloc_hook() directly. */ - ret = __slab_alloc_node(s, gfp_flags, node, &ac); + ret = __slab_alloc_node(s, gfp_flags, node, ac); /* * It's possible we failed due to trylock as we preempted someone with @@ -5467,11 +5462,23 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in success: maybe_wipe_obj_freeptr(s, ret); - slab_post_alloc_hook(s, gfp_flags, 1, &ret, &ac); + slab_post_alloc_hook(s, gfp_flags, 1, &ret, ac); - ret = kasan_kmalloc(s, ret, orig_size, gfp_flags); + ret = kasan_kmalloc(s, ret, ac->orig_size, gfp_flags); return ret; } + +void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, int node) +{ + const struct slab_alloc_context ac = { + .caller_addr = _RET_IP_, + .orig_size = size, + .alloc_flags = SLAB_ALLOC_NOLOCK, + }; + + return __kmalloc_nolock_noprof(PASS_TOKEN_PARAMS(size, token), + gfp_flags, node, &ac); +} EXPORT_SYMBOL_GPL(_kmalloc_nolock_noprof); void *__kmalloc_node_track_caller_noprof(DECL_KMALLOC_PARAMS(size, b, token), gfp_t flags, @@ -5525,6 +5532,30 @@ void *__kmalloc_cache_node_noprof(struct kmem_cache *s, gfp_t gfpflags, } EXPORT_SYMBOL(__kmalloc_cache_node_noprof); +/* + * The only version of kmalloc_node() that takes alloc_flags and thus can + * determine on its own whether to handle the allocation via kmalloc_nolock() or + * normally + */ +void *__kmalloc_flags_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t flags, + unsigned int alloc_flags, int node) +{ + const struct slab_alloc_context ac = { + .caller_addr = _RET_IP_, + .orig_size = size, + .alloc_flags = alloc_flags, + }; + + if (alloc_flags_allow_spinning(alloc_flags)) { + return __do_kmalloc_node(NULL, flags, node, + PASS_TOKEN_PARAM(token), &ac); + } else { + return __kmalloc_nolock_noprof(PASS_TOKEN_PARAMS(size, token), + flags, node, &ac); + } +} + + static noinline void free_to_partial_list( struct kmem_cache *s, struct slab *slab, void *head, void *tail, int bulk_cnt, -- 2.54.0