From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f179.google.com (mail-pl1-f179.google.com [209.85.214.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A2B93C4175 for ; Thu, 11 Jun 2026 09:48:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781171292; cv=none; b=ISGmSCFpIFU1+qsZeRUV2n+3fdbpi5m4CxTyImpPIiunBpqQzxu2/OLbd6h+dEGx9Am6xmkdAvVCGYirw8tTENNCZcZaIKsCrtiS9bF/DZONgrYbiUHDe6Mi71KezeHGSSOzRNe/KI8iIagVUgb+YoJ02EHnL38kb9WFBAiI7Ss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781171292; c=relaxed/simple; bh=Vh3RfOBQyFbdorHRXyGPsab5qScaelImnIESEg3NJeY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=gccRmNC+jVBIxrfbg1ClTlOuNOJDEBwOSDRyCqiCLeL5xz6gUJj2Wxqqvx6KJq95blXGxLadaMYqI6nOQV6UHX2txq0o1SjdNm7fE22N+q5zYg1wux6OvEE8DNQWgnU9ElN/MRE1N95dGDgG1p93z3GMxAUmzv+EfZTdEqHl+94= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=C0h/zxYq; arc=none smtp.client-ip=209.85.214.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="C0h/zxYq" Received: by mail-pl1-f179.google.com with SMTP id d9443c01a7336-2c0c2c7d45eso70200395ad.1 for ; Thu, 11 Jun 2026 02:48:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781171290; x=1781776090; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=RgDnCy/Lqt4KlSBPy89Hrdxm/Zy1/HrZbOMvwPuOqc8=; b=C0h/zxYqfl+DVo4KkUJT2vkci1bY7gDj4SBOse43b6dTmwEJAuqN1m/HWabmA9//IO h/3M6bQQlPPItVIwMe9DK3+u6VKjbKfzW1fctwDwO3y8hTEaSgalCcyOxbwqHdi8c2kj ijFyUAlIdMQEF08E6ob6yq4mq9+ss6b0ZvefcN6bYg4Niu5x1wKl3l5cPe9yxYUeOEpE JLent4t8ghRewggHT+tfTnPYq8W4SdHBlmfdD3Fv4UdCEmQ+0UBODQXyUJNSZ3oIZbT0 /eXzxUcBcA7k1wF8Y5nICjOJ3eAKFVIqbv0TuzDV/NH69RsNemgE3E09geVna7yAvp48 Bzvg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781171290; x=1781776090; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=RgDnCy/Lqt4KlSBPy89Hrdxm/Zy1/HrZbOMvwPuOqc8=; b=fSxI5jm+yN8qjY3ci3han2GkEfAoK9wqz+OfX5SFi3qEoFmuwtZS+XFHwsVWn+p6yz pJ4GeWtJa+0EzH6EhtJxBT1QGIFtbjOJz3HjcfHCRbudWB1O99fiyqlT1jAelxPew+M6 pG1Mzh8mdA8/zLmox8jvrJMR/tHKvH/OyEifRZXUsTmx2rJZCeInAx2w9qV5bQ1ygSbS gcRzisXtN1F0pr6KGJppc/I15hKAZidCzXp66yW2WU61/4/B3rtHTqA4LFY/JIC0bJ8m eBYgWrE1whmS9JDqAkWYRZqNRtCZU4YLdbb7FODD/L2Cg04bhAMx7ZQIJzCjCNdtS/xz ZSyA== X-Forwarded-Encrypted: i=1; AFNElJ8ntoOBdBnVwEZMLzQ1fN9OBe/ibkUepSKZR7Un4e0V+qjbvkliBsdRSbpVOW5j+cwaCZAnwMEJdPFkFEg=@vger.kernel.org X-Gm-Message-State: AOJu0YxKsF8ktaqpg3XL86ZQFcJFq4plEyL09RL4gSjrNfA/PrQ9bswJ CKnlXk6PkbpzjoQqjzMvxdtWrBd5dFnh8eTPgFM+1LuY8y/uOh0M1/hU X-Gm-Gg: Acq92OF5eppBgrG18Gi8yJOVIE+WcC8DfJFaJwFSG3xHInO9FNa4q0fAUV/rK5xocVO 9DG096LnAYROBIM3iagVFMe+Us1MQAbqSvwpieHB9oQGFVVK0bXLkR/pnFsgleOf0DLUjPTMbdr HPiS6GBuJbKelANE9AZ23zZwpFlrs9DFgi6ynlFrjIs8JE7PKguks9auG3YsWFrterN6Dyp00+A RFpBHDNtYgxQCRtIEfS+bP1g5MlLKTgHXPdfnQkTL1QOsw/9thtiHe0u4Y+0WlJ4oUZGQpOHe19 1jL9COU4YWsgUI/qeit5kjbP4Bu3RZkmGcY23k8Zk+BmgEQ6iTKp8kx/juFzeT5R3S2O/9BMUrw NzDGT1HCw43uaOdfZaC7Bt65TzN/dooQHBC27k6MMh/UsEi7gxvB5R8ImUNac/ydXpp/6YW/HDj LsQUKfyQdtdbXKv92GglPZBX/nEwBYg0ISEdosWYZB8UU= X-Received: by 2002:a17:903:38c4:b0:2ba:4e84:966 with SMTP id d9443c01a7336-2c2f2a77a19mr24838595ad.36.1781171290236; Thu, 11 Jun 2026 02:48:10 -0700 (PDT) Received: from pve-server.rlab ([49.205.216.49]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c16629d042sm283324905ad.60.2026.06.11.02.48.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jun 2026 02:48:09 -0700 (PDT) From: "Ritesh Harjani (IBM)" To: linux-mm@kvack.org Cc: Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , David Hildenbrand , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sayali Patil , "Ritesh Harjani (IBM)" Subject: [PATCH v2 1/3] mm, swap: make SWAPFILE_CLUSTER runtime Date: Thu, 11 Jun 2026 15:17:51 +0530 Message-Id: <442a71907f1dddf12c55a74c0aa24fb70e3fb412.1781170904.git.ritesh.list@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On PowerPC Book3S64, MMU is selected at runtime, so macros like PMD_SHIFT are effectively runtime variables in the Book3S64 code. THP swap code uses these macros to size some of its array data structures based on PMD_ORDER e.g. SWAPFILE_CLUSTER macro is used for this very purpose. Hence this patch initializes SWAPFILE_CLUSTER at runtime and also modifies swap_table and swap_memcg_table which were earlier using this macro for defining the number of table entries. Signed-off-by: Ritesh Harjani (IBM) --- mm/swap.h | 5 +++-- mm/swap_table.h | 6 ++---- mm/swapfile.c | 27 ++++++++++++++++++++++----- 3 files changed, 27 insertions(+), 11 deletions(-) diff --git a/mm/swap.h b/mm/swap.h index 77d2d14eda42..956879a69ddd 100644 --- a/mm/swap.h +++ b/mm/swap.h @@ -26,11 +26,12 @@ extern int page_cluster; #define SWAP_TABLE_HAS_ZEROFLAG ((BITS_PER_LONG - SWAP_CACHE_PFN_MARK_BITS - \ SWAP_CACHE_PFN_BITS) > SWAP_COUNT_MIN_BITS) +extern unsigned int swap_slots_in_cluster __read_mostly; +#define SWAPFILE_CLUSTER swap_slots_in_cluster + #ifdef CONFIG_THP_SWAP -#define SWAPFILE_CLUSTER HPAGE_PMD_NR #define swap_entry_order(order) (order) #else -#define SWAPFILE_CLUSTER 256 #define swap_entry_order(order) 0 #endif diff --git a/mm/swap_table.h b/mm/swap_table.h index e6613e62f8d0..90e2a7852300 100644 --- a/mm/swap_table.h +++ b/mm/swap_table.h @@ -8,16 +8,14 @@ /* A typical flat array in each cluster as swap table */ struct swap_table { - atomic_long_t entries[SWAPFILE_CLUSTER]; + DECLARE_FLEX_ARRAY(atomic_long_t, entries); }; /* For storing memcg private id */ struct swap_memcg_table { - unsigned short id[SWAPFILE_CLUSTER]; + DECLARE_FLEX_ARRAY(unsigned short, id); }; -#define SWP_TABLE_USE_PAGE (sizeof(struct swap_table) == PAGE_SIZE) - /* * A swap table entry represents the status of a swap slot on a swap * (physical or virtual) device. The swap table in each cluster is a diff --git a/mm/swapfile.c b/mm/swapfile.c index 78b49b0658ad..016a5aa0cb93 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -129,6 +129,17 @@ static DEFINE_PER_CPU(struct percpu_swap_cluster, percpu_swap_cluster) = { .lock = INIT_LOCAL_LOCK(), }; +unsigned int swap_slots_in_cluster __read_mostly; +bool swap_table_use_page __read_mostly; + +static unsigned int generic_swap_slots_in_clusters(void) +{ + if (IS_ENABLED(CONFIG_THP_SWAP)) + return HPAGE_PMD_NR; + else + return 256; +} + /* May return NULL on invalid type, caller must check for NULL return */ static struct swap_info_struct *swap_type_to_info(int type) { @@ -437,7 +448,7 @@ static void swap_cluster_free_table(struct swap_cluster_info *ci) return; rcu_assign_pointer(ci->table, NULL); - if (!SWP_TABLE_USE_PAGE) { + if (!swap_table_use_page) { kmem_cache_free(swap_table_cachep, table); return; } @@ -456,7 +467,7 @@ static int swap_cluster_alloc_table(struct swap_cluster_info *ci, gfp_t gfp) if (rcu_access_pointer(ci->table)) return 0; - if (SWP_TABLE_USE_PAGE) { + if (swap_table_use_page) { folio = folio_alloc(gfp | __GFP_ZERO, 0); if (folio) table = folio_address(folio); @@ -471,7 +482,8 @@ static int swap_cluster_alloc_table(struct swap_cluster_info *ci, gfp_t gfp) #ifdef CONFIG_MEMCG if (!mem_cgroup_disabled()) { VM_WARN_ON_ONCE(ci->memcg_table); - ci->memcg_table = kzalloc_obj(*ci->memcg_table, gfp); + ci->memcg_table = kzalloc_flex(*ci->memcg_table, id, + SWAPFILE_CLUSTER, gfp); if (!ci->memcg_table) { swap_cluster_free_table(ci); return -ENOMEM; @@ -3912,14 +3924,19 @@ static int __init swapfile_init(void) { swapfile_maximum_size = arch_max_swapfile_size(); + swap_slots_in_cluster = generic_swap_slots_in_clusters(); + swap_table_use_page = + (swap_slots_in_cluster * sizeof(atomic_long_t) == PAGE_SIZE); + /* * Once a cluster is freed, it's swap table content is read * only, and all swap cache readers (swap_cache_*) verifies * the content before use. So it's safe to use RCU slab here. */ - if (!SWP_TABLE_USE_PAGE) + if (!swap_table_use_page) swap_table_cachep = kmem_cache_create("swap_table", - sizeof(struct swap_table), + struct_size_t(struct swap_table, entries, + SWAPFILE_CLUSTER), 0, SLAB_PANIC | SLAB_TYPESAFE_BY_RCU, NULL); #ifdef CONFIG_MIGRATION -- 2.39.5