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b=O+lAReT+de6tcsvpGObqmLv84nKfJpswHPzAsYVqWrSc1Rm5kscoCNYsBp3VqEiCj Cr5rpl5kMEms+MH3xFCJL1bGnE1fKZjYD19QtwgDsBl8c6K0xoAG6k8MT3VGaI5jEP bVfpGaWs6N3RVr+MvZKISWQ/KaPIhRJDvad4or6/t40uemY6/LuU3W2UWvFf5EHyn0 wYBOC0rZ1Qik7J+SbjLCAmY6lZdbqjUQlyVleLXVNV0ucwQj2vhsT5sUz22NYVWn3V q+IJR5eeFHB61kJK67afYWzLr/XEzT9a8L2+h63lGCac32xze8X63Gn9HxsmoMlTWV nRf6aXvzeJpeQ== From: "Vlastimil Babka (SUSE)" Date: Tue, 09 Jun 2026 11:17:57 +0200 Subject: [PATCH RFC 12/15] mm/slab: introduce kmalloc_flags() MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260609-slab_alloc_flags-v1-12-2bf4a4b9b526@kernel.org> References: <20260609-slab_alloc_flags-v1-0-2bf4a4b9b526@kernel.org> In-Reply-To: <20260609-slab_alloc_flags-v1-0-2bf4a4b9b526@kernel.org> To: Harry Yoo Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Suren Baghdasaryan , Alexei Starovoitov , Andrew Morton , Johannes Weiner , Michal Hocko , Shakeel Butt , Alexander Potapenko , Marco Elver , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, "Vlastimil Babka (SUSE)" X-Mailer: b4 0.15.2 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A0BA9180003 X-Stat-Signature: ya6sgnp9n6phn3txws7b3e6trg7aptbu X-Rspam-User: X-HE-Tag: 1780996722-507999 X-HE-Meta: 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 zxR8afKt Jst0/TpYjeMpggd4KeXyvlQgCoZ1nYymTwbBRthimxco65xfMMFlWokHugP2bLgMldxeL6C6i83LNNX+zQh5PDU+96WDTPCj5S3GJssIGYe7UUimXy4r/T16SKjDBJ3vDSK1QraONLp8Zw29LjcALobB3dqFqzp3TpzUKshJnGHikf0YSe5e/nCOsNdS/x9+Toz1GDJHiyoI0mnh0S4btHXVrR57cFitniQm5LRdOjByxnxjEdpJCuXkj6k93I1OfjlFEYe69dCaweBTbQgq1fH+VqxamajbE5kDy Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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_TRYLOCK 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. Signed-off-by: Vlastimil Babka (SUSE) --- include/linux/slab.h | 12 +++++++++++ mm/slub.c | 56 ++++++++++++++++++++++++++++++++++++++++------------ 2 files changed, 55 insertions(+), 13 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index ce1c867dc0ba..11e82fdbe8d3 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -944,6 +944,10 @@ void *__kmalloc_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t flags) void *__kmalloc_node_noprof(DECL_KMALLOC_PARAMS(size, b, token), gfp_t flags, int node) __assume_kmalloc_alignment __alloc_size(1); +void *__kmalloc_flags_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t flags, + unsigned int alloc_flags, int node) + __assume_kmalloc_alignment __alloc_size(1); + void *__kmalloc_cache_noprof(struct kmem_cache *s, gfp_t flags, size_t size) __assume_kmalloc_alignment __alloc_size(3); @@ -1176,6 +1180,14 @@ static __always_inline __alloc_size(1) void *_kmalloc_node_noprof(size_t size, g #define kmalloc_node_noprof(...) _kmalloc_node_noprof(__VA_ARGS__, __kmalloc_token(__VA_ARGS__)) #define kmalloc_node(...) alloc_hooks(kmalloc_node_noprof(__VA_ARGS__)) +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__)) + static inline __alloc_size(1, 2) void *_kmalloc_array_noprof(size_t n, size_t size, gfp_t flags, kmalloc_token_t token) { size_t bytes; diff --git a/mm/slub.c b/mm/slub.c index c11edd58b52d..86691eb14002 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5370,15 +5370,15 @@ 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, struct slab_alloc_context *ac) { gfp_t alloc_gfp = __GFP_NOWARN | __GFP_NOMEMALLOC | gfp_flags; - size_t orig_size = size; - unsigned int alloc_flags = SLAB_ALLOC_TRYLOCK; struct kmem_cache *s; bool can_retry = true; void *ret; + 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)); @@ -5413,23 +5413,17 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in */ return NULL; - ret = alloc_from_pcs(s, alloc_gfp, alloc_flags, node); + ret = alloc_from_pcs(s, alloc_gfp, ac->alloc_flags, node); if (ret) goto success; - struct slab_alloc_context ac = { - .caller_addr = _RET_IP_, - .orig_size = orig_size, - .alloc_flags = alloc_flags, - }; - /* * Do not call slab_alloc_node(), since trylock mode isn't * compatible with slab_pre_alloc_hook/should_failslab and * kfence_alloc. Hence call __slab_alloc_node() (at most twice) * and slab_post_alloc_hook() directly. */ - ret = __slab_alloc_node(s, alloc_gfp, node, &ac); + ret = __slab_alloc_node(s, alloc_gfp, node, ac); /* * It's possible we failed due to trylock as we preempted someone with @@ -5452,11 +5446,23 @@ 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, alloc_gfp, 1, &ret, &ac); + slab_post_alloc_hook(s, alloc_gfp, 1, &ret, ac); - ret = kasan_kmalloc(s, ret, orig_size, alloc_gfp); + ret = kasan_kmalloc(s, ret, ac->orig_size, alloc_gfp); return ret; } + +void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, int node) +{ + struct slab_alloc_context ac = { + .caller_addr = _RET_IP_, + .orig_size = size, + .alloc_flags = SLAB_ALLOC_TRYLOCK, + }; + + 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, @@ -5510,6 +5516,30 @@ 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) +{ + 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(size, 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