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Fri, 7 Nov 2025 13:51:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id yP8JH3L5DWlFCwAAD6G6ig (envelope-from ); Fri, 07 Nov 2025 13:51:46 +0000 From: Vlastimil Babka Date: Fri, 07 Nov 2025 14:51:23 +0100 Subject: [PATCH 1/4] slab: separate struct freelist_tid from kmem_cache_cpu MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251107-slab-fms-cleanup-v1-1-650b1491ac9e@suse.cz> References: <20251107-slab-fms-cleanup-v1-0-650b1491ac9e@suse.cz> In-Reply-To: <20251107-slab-fms-cleanup-v1-0-650b1491ac9e@suse.cz> To: linux-mm@kvack.org Cc: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , linux-kernel@vger.kernel.org, Vlastimil Babka X-Mailer: b4 0.14.3 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B33C94000F X-Stat-Signature: 7sgny61zc9rtcjqqzuqh5jqonpg6w8po X-HE-Tag: 1762523520-35809 X-HE-Meta: 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 BDqt+KWz 5DGyODpKUUKbpsxdlTZdo8uptE5tfn/u9w+Cek/h7MZt+2cdgQq6z8ciirGN5/hNjZ+1wRc0O+ok9x/Za063myBah2gjtBVdit46Ie0Yjlik+Y9HITP7qbcjMGETfrXg0MVk0J96RSehp4Z+UNbJVC044i8MzLdMATi2/Wr53tY/7YLGXcy/njWGDm+EsylxBDidVHYIKMuO0YhYZw2dfGyugMm1AMmglBnoMGgRYaPs+52zVPyXBXUESr+6/ZQPirpN/TAa2qsRtNaamPGSwIIw7k+CjKM8v4PKbG6D/mB7Exec= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: In kmem_cache_cpu we currently have a union of the freelist+tid pair with freelist_aba_t, relying implicitly on the type compatibility with the freelist+counters pair used in freelist_aba_t. To allow further changes to freelist_aba_t, we can instead define a separate struct freelist_tid (instead of a typedef, per the coding style) for kmem_cache_cpu, as that affects only a single helper __update_cpu_freelist_fast(). We can add the resulting struct freelist_tid to kmem_cache_cpu as unnamed field thanks to -fms-extensions, so that freelist and tid fields can still be accessed directly. Signed-off-by: Vlastimil Babka --- mm/slub.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 074abe8e79f8..5f6408c9e0fd 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -411,18 +411,22 @@ enum stat_item { }; #ifndef CONFIG_SLUB_TINY -/* - * When changing the layout, make sure freelist and tid are still compatible - * with this_cpu_cmpxchg_double() alignment requirements. - */ -struct kmem_cache_cpu { +struct freelist_tid { union { struct { - void **freelist; /* Pointer to next available object */ + void *freelist; /* Pointer to next available object */ unsigned long tid; /* Globally unique transaction id */ }; - freelist_aba_t freelist_tid; + freelist_full_t freelist_tid; }; +}; + +/* + * When changing the layout, make sure freelist and tid are still compatible + * with this_cpu_cmpxchg_double() alignment requirements. + */ +struct kmem_cache_cpu { + struct freelist_tid; struct slab *slab; /* The slab from which we are allocating */ #ifdef CONFIG_SLUB_CPU_PARTIAL struct slab *partial; /* Partially allocated slabs */ @@ -4367,11 +4371,11 @@ __update_cpu_freelist_fast(struct kmem_cache *s, void *freelist_old, void *freelist_new, unsigned long tid) { - freelist_aba_t old = { .freelist = freelist_old, .counter = tid }; - freelist_aba_t new = { .freelist = freelist_new, .counter = next_tid(tid) }; + struct freelist_tid old = { .freelist = freelist_old, .tid = tid }; + struct freelist_tid new = { .freelist = freelist_new, .tid = next_tid(tid) }; - return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid.full, - &old.full, new.full); + return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid, + &old.freelist_tid, new.freelist_tid); } /* -- 2.51.1