From nobody Mon Feb 9 06:48:18 2026 Received: from smtpout.efficios.com (smtpout.efficios.com [158.69.130.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE614262FFF for ; Sun, 21 Dec 2025 23:29:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=158.69.130.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766359794; cv=none; b=ZKFmHu2J5xRpyNE73ymkT7xyg7S1LeKOxZZXP9Byal9KShzFfF73uJfdCOrJ3lxvNV7HeXAMblyyHNEnY4idx12HZA0kVBJIoWETkSdXm+h8SiyDfW1fjorybyEbjk+/9xwL4XGqdY3yhAkqpB4NavVqkJqNtV5gaUHFMv/M9vw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766359794; c=relaxed/simple; bh=97Bba2IVpIiZDuW5qVn6n2hCZ28cMWY6G+U8FCejAAY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=DJOQMEIf+Z9Nq+fDEnqgQ99aao2VeLfwqZzdwIioEi+1Clen60Db4fSm0nW6oVkYzKwWKTuUMEaAU9F9N/se80xz7Ru4PVppltjhOYIFtGVP1pVqOZH4Nhnd2sDU1XboQhlvTkGoVETpCudtFrYHQuDo2LIQEe+wdsVVWaPPH4Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=cnc5f6qK; arc=none smtp.client-ip=158.69.130.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="cnc5f6qK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=smtpout1; t=1766359786; bh=bggeet/K7f/LykaY9i5CXV4NsffNnOWo1S/CrVN1N6M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cnc5f6qKjNWTp5CYe3FtMEqXjaEtwaL5KnWMM06i0PVH+WPEPspj9cYDBTvZjbAPl LzhO4ykoMqjew6uDzSWYAvjT8sxTLGeysoAT8/VuHK8OtbbJhFcglGCLLqg6OM/ZkN tvdwIJRnC5/3tsUuE7EGMICCVIIMcQ9G/qN7IPcE3YGzNsCiCPLx2qF4E8Udx0p2A+ PweF6eTwZbqfCL1RTbXB3X3iGZMNYbMtwpkC5bWW1IvClcXM2Hm6U9NyHK/jREt4e+ up7IXK3+ZoobM0LaQmmelFCWFxr5h46TnAOOrWVS5lDZTwNHt8mgMKVRphjb1MvLTe JYWkOBKaZF2aA== Received: from thinkos.internal.efficios.com (unknown [IPv6:2606:6d00:100:4000:6450:b8a1:16cf:5ecf]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4dZHYQ1VJHzdCd; Sun, 21 Dec 2025 18:29:46 -0500 (EST) From: Mathieu Desnoyers To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Mark Brown , linux-mm@kvack.org Subject: [PATCH v1 2/5] mm: Rename cpu_bitmap field to flexible_array Date: Sun, 21 Dec 2025 18:29:23 -0500 Message-Id: <20251221232926.450602-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20251221232926.450602-1-mathieu.desnoyers@efficios.com> References: <20251221232926.450602-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The cpu_bitmap flexible array now contains more than just the cpu_bitmap. In preparation for changing the static mm_struct definitions to cover for the additional space required, change the cpu_bitmap type from "unsigned long" to "char", require an unsigned long alignment of the flexible array, and rename the field from "cpu_bitmap" to "flexible_array". Introduce the MM_STRUCT_FLEXIBLE_ARRAY_INIT macro to statically initialize the flexible array. This covers the init_mm and efi_mm static definitions. This is a preparation step for fixing the missing mm_cid size for static mm_struct definitions. Signed-off-by: Mathieu Desnoyers Cc: Andrew Morton Cc: Mark Brown Cc: linux-mm@kvack.org --- drivers/firmware/efi/efi.c | 2 +- include/linux/mm.h | 2 +- include/linux/mm_types.h | 13 +++++++++---- mm/init-mm.c | 2 +- 4 files changed, 12 insertions(+), 7 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index a9070d00b833..3f5c2ae50024 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -73,10 +73,10 @@ struct mm_struct efi_mm =3D { MMAP_LOCK_INITIALIZER(efi_mm) .page_table_lock =3D __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock), .mmlist =3D LIST_HEAD_INIT(efi_mm.mmlist), - .cpu_bitmap =3D { [BITS_TO_LONGS(NR_CPUS)] =3D 0}, #ifdef CONFIG_SCHED_MM_CID .mm_cid.lock =3D __RAW_SPIN_LOCK_UNLOCKED(efi_mm.mm_cid.lock), #endif + .flexible_array =3D MM_STRUCT_FLEXIBLE_ARRAY_INIT, }; =20 struct workqueue_struct *efi_rts_wq; diff --git a/include/linux/mm.h b/include/linux/mm.h index 890dab720f75..8d9e3239d2cc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2853,7 +2853,7 @@ static inline struct percpu_counter_tree_level_item *= get_rss_stat_items(struct m { unsigned long ptr =3D (unsigned long)mm; =20 - ptr +=3D offsetof(struct mm_struct, cpu_bitmap); + ptr +=3D offsetof(struct mm_struct, flexible_array); /* Skip cpu_bitmap */ ptr +=3D cpumask_size(); /* Skip mm_cidmask */ diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index a6287d07efb7..1531df8cda52 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1329,7 +1329,7 @@ struct mm_struct { * The mm_cpumask needs to be at the end of mm_struct, because it * is dynamically sized based on nr_cpu_ids. */ - unsigned long cpu_bitmap[]; + char flexible_array[] __aligned(__alignof__(unsigned long)); }; =20 /* Copy value to the first system word of mm flags, non-atomically. */ @@ -1366,19 +1366,24 @@ static inline void __mm_flags_set_mask_bits_word(st= ruct mm_struct *mm, MT_FLAGS_USE_RCU) extern struct mm_struct init_mm; =20 +#define MM_STRUCT_FLEXIBLE_ARRAY_INIT \ +{ \ + [0 ... sizeof(cpumask_t)-1] =3D 0 \ +} + /* Pointer magic because the dynamic array size confuses some compilers. */ static inline void mm_init_cpumask(struct mm_struct *mm) { unsigned long cpu_bitmap =3D (unsigned long)mm; =20 - cpu_bitmap +=3D offsetof(struct mm_struct, cpu_bitmap); + cpu_bitmap +=3D offsetof(struct mm_struct, flexible_array); cpumask_clear((struct cpumask *)cpu_bitmap); } =20 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ static inline cpumask_t *mm_cpumask(struct mm_struct *mm) { - return (struct cpumask *)&mm->cpu_bitmap; + return (struct cpumask *)&mm->flexible_array; } =20 #ifdef CONFIG_LRU_GEN @@ -1469,7 +1474,7 @@ static inline cpumask_t *mm_cpus_allowed(struct mm_st= ruct *mm) { unsigned long bitmap =3D (unsigned long)mm; =20 - bitmap +=3D offsetof(struct mm_struct, cpu_bitmap); + bitmap +=3D offsetof(struct mm_struct, flexible_array); /* Skip cpu_bitmap */ bitmap +=3D cpumask_size(); return (struct cpumask *)bitmap; diff --git a/mm/init-mm.c b/mm/init-mm.c index a514f8ce47e3..c5556bb9d5f0 100644 --- a/mm/init-mm.c +++ b/mm/init-mm.c @@ -47,7 +47,7 @@ struct mm_struct init_mm =3D { #ifdef CONFIG_SCHED_MM_CID .mm_cid.lock =3D __RAW_SPIN_LOCK_UNLOCKED(init_mm.mm_cid.lock), #endif - .cpu_bitmap =3D CPU_BITS_NONE, + .flexible_array =3D MM_STRUCT_FLEXIBLE_ARRAY_INIT, INIT_MM_CONTEXT(init_mm) }; =20 --=20 2.39.5