From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9CEE2FF8855 for ; Tue, 5 May 2026 15:39:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7699C6B00B9; Tue, 5 May 2026 11:39:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4F7186B00BA; Tue, 5 May 2026 11:39:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 398346B00B9; Tue, 5 May 2026 11:39:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 29F196B00B7 for ; Tue, 5 May 2026 11:39:38 -0400 (EDT) Received: from smtpin17.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id C6C231C0DC0 for ; Tue, 5 May 2026 15:39:37 +0000 (UTC) X-FDA: 84733775994.17.654825A Received: from mail-oa1-f47.google.com (mail-oa1-f47.google.com [209.85.160.47]) by imf06.hostedemail.com (Postfix) with ESMTP id 09120180017 for ; Tue, 5 May 2026 15:39:35 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=kkEti+s6; spf=pass (imf06.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.160.47 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1777995576; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=wIXfyZUJZPSdof5KqpSbjmh+gBcKfo2nAX8OXquADG0=; b=rWXRtzP0UrX9ZMXy3A2AaikAGSwyKLP7Z/JZdxPYFyG/akyS+5+VlfmQGJ6Q/h/LnQg1OU EKMm+UGJ7swrcQG+Rjq6xvCegRqnjIu0bImR4LNvJnRMrmycM9TIjTqGWEwakvMAItt3dt yaEPV6xSEhIAdhZF4UZHrOD5wtXvwCg= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1777995576; a=rsa-sha256; cv=none; b=TvqPJElQ2a91TwibWmJE1btMz71+Ta+T3dMoRy+8afenNqSqdO7TFEun7grkIsyq9rg9m0 QFk3bKCLunDBE8Vh5WUw4c+02J32zZogf1flYT6Ls8b94OsR+AC1DyFxUmKn2xaz6MK00u 2WxoEBTD2wSmgx0ulcMdMW9Iy1zRMqI= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=kkEti+s6; spf=pass (imf06.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.160.47 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com Received: by mail-oa1-f47.google.com with SMTP id 586e51a60fabf-40974bf7781so7071fac.0 for ; Tue, 05 May 2026 08:39:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777995575; x=1778600375; darn=kvack.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=wIXfyZUJZPSdof5KqpSbjmh+gBcKfo2nAX8OXquADG0=; b=kkEti+s6peoK20x0nld8xh98L63Fr+FSEGF5fVtFDrxk7MD51vk04PBc9nJ7qfz+5j vgU+J2d+so5ICwQes6avhxQ6z5/J4LSFTe+WjQCK/ZHl6P4joMfqP1cYvRljg0fL4gun A4tiBZdrwE3ww6wF+1Vb2TCbs7tqZ6R8BqjQJEml077j1pmemuCXPtcU2gaDeOGxHO75 lNiPTGjs9upW0C6CMfix9kSoOUPBQOwsJs0PZ9Rq7gQwmpb0ghdtx5kkYJKAlF/HXkex BTAZUuGa9isy4viElAiDqZ7Jx13Uv5BswtINZbuHJR3mtHE2pfAm4SzUYPz7lgbPgFok wtwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777995575; x=1778600375; 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=wIXfyZUJZPSdof5KqpSbjmh+gBcKfo2nAX8OXquADG0=; b=kNDUexMulKXSia0cpBb4UG2Q+zYUyNn3qKFcEBg9m+1oVxREWTDAS1zZAzyjVmP2Ql B3UKXBgSEzyIIoIHWtOIJwOcGocb7IlwIbzg+YA03yzqQj+b1D0Sv+OKjG5ZAPWMTaHO 3Vq1HpiPwMzoCxcM/KDLwCtCi1RvAAMam5vNa9PAGWZZzDsUl426eyMSFMN3oK5a546s OdMm20YWCD8bcZ8VDMuXfr7hnvwjK0WekPGzPtICVi++hGTWKtdB1hiceD/MgoCU59vG 1e/+ejTmj4ZPp98qLk5MknZD6qYIA/YM0inrYONA3bJzgM/ZoC28auuPm9c6hqp8wist pCdA== X-Forwarded-Encrypted: i=1; AFNElJ/h1WipCCH6J4H9TJkO6DL/gyzUchkrVexsqIAB4sA74StESUytb0A582KAk3Q6XvqsqA1O+sTiuQ==@kvack.org X-Gm-Message-State: AOJu0YyA9lOt0T/QF8sxw4+DXbki4CMnpXsrvmEDNWo8KMHR+pN3KRTK QxXYrMYJ10nhJx77mAvg/7ft14LE+ppTC0x6cFVVBskHbwHkb9klfk6O X-Gm-Gg: AeBDietNp3UgsFYb17Ba4gLyOMu7slMI2x7TcbvluXM15u4grl8xuSs4J73i3g4RHWg xA+v7nIRCy+6v7HoAs7LXJJ1PLumT/kT0AeaovqdxEFpJf40ATbr8R54Wie4Y88PWY5klpVcd49 b+GpxAaNDPc74/4+tMRSCCm0cQnFZXDeeY/MAbVz3RPKfrBND6lSfVPcBHM7yyXqP+YuIYJgI54 fw6HFiXBitIQQpChHYUnCm3zdgmFdjlAym1KKSzfrjr3U+R7yvedbxetVxAnNbXZOFN9n/J1uLH qtMwgSyeqwzZY860Y+T831EStgz0MT+iXxnWhyO1DCkLF71Th39g6aPtA36GJ8f5DFwORD7Tgxm /UnX3iU3pv3yebZ5u6ZICB5+ZaGxYjzqbSUlMMm8EI/DobT9WvudTKJR3CI0wUOFKF2udDr2szv dPsDElbN2UQvQm+OIku8Qt/o/vuo2P+MCLi8LV/dn3o6bXVnhfaqpgdeQ= X-Received: by 2002:a05:6870:c188:b0:42d:8229:ba3d with SMTP id 586e51a60fabf-434d0d61313mr2042459fac.11.1777995574917; Tue, 05 May 2026 08:39:34 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:8::]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-434549540b2sm14234808fac.6.2026.05.05.08.39.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2026 08:39:34 -0700 (PDT) From: Nhat Pham To: kasong@tencent.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, apopple@nvidia.com, axelrasmussen@google.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, bhe@redhat.com, byungchul@sk.com, cgroups@vger.kernel.org, chengming.zhou@linux.dev, chrisl@kernel.org, corbet@lwn.net, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jannh@google.com, joshua.hahnjy@gmail.com, lance.yang@linux.dev, lenb@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, mhocko@suse.com, muchun.song@linux.dev, npache@redhat.com, nphamcs@gmail.com, pavel@kernel.org, peterx@redhat.com, peterz@infradead.org, pfalcato@suse.de, rafael@kernel.org, rakie.kim@sk.com, roman.gushchin@linux.dev, rppt@kernel.org, ryan.roberts@arm.com, shakeel.butt@linux.dev, shikemeng@huaweicloud.com, surenb@google.com, tglx@kernel.org, vbabka@suse.cz, weixugc@google.com, ying.huang@linux.alibaba.com, yosry.ahmed@linux.dev, yuanchu@google.com, zhengqi.arch@bytedance.com, ziy@nvidia.com, kernel-team@meta.com, riel@surriel.com, haowenchao22@gmail.com Subject: [PATCH v6 17/22] swapfile: remove zeromap bitmap Date: Tue, 5 May 2026 08:38:46 -0700 Message-ID: <20260505153854.1612033-18-nphamcs@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260505153854.1612033-1-nphamcs@gmail.com> References: <20260505153854.1612033-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 09120180017 X-Stat-Signature: pd1der3zcfbypqkzf1fykwxctypkfo41 X-Rspam-User: X-HE-Tag: 1777995575-130369 X-HE-Meta: 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 2n6mfaSw 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Zero swap entries are now treated as a separate, decoupled backend in the virtual swap layer. The zeromap bitmap of physical swapfile is no longer used - remove it. This does not have any behavioral change, and save 1 bit per swap page in terms of memory overhead. Signed-off-by: Nhat Pham --- include/linux/swap.h | 1 - mm/swapfile.c | 30 +++++------------------------- 2 files changed, 5 insertions(+), 26 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 12dd9621b637..4d152fa811f2 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -260,7 +260,6 @@ struct swap_info_struct { signed char type; /* strange name for an index */ unsigned int max; /* extent of the swap_map */ unsigned char *swap_map; /* vmalloc'ed array of usage counts */ - unsigned long *zeromap; /* kvmalloc'ed bitmap to track zero pages */ struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ struct list_head free_clusters; /* free clusters list */ struct list_head full_clusters; /* full clusters list */ diff --git a/mm/swapfile.c b/mm/swapfile.c index c6a91c657877..ce1254733e96 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2276,8 +2276,7 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) static void setup_swap_info(struct swap_info_struct *si, int prio, unsigned char *swap_map, - struct swap_cluster_info *cluster_info, - unsigned long *zeromap) + struct swap_cluster_info *cluster_info) { si->prio = prio; /* @@ -2288,7 +2287,6 @@ static void setup_swap_info(struct swap_info_struct *si, int prio, si->avail_list.prio = -si->prio; si->swap_map = swap_map; si->cluster_info = cluster_info; - si->zeromap = zeromap; } static void _enable_swap_info(struct swap_info_struct *si) @@ -2306,12 +2304,11 @@ static void _enable_swap_info(struct swap_info_struct *si) static void enable_swap_info(struct swap_info_struct *si, int prio, unsigned char *swap_map, - struct swap_cluster_info *cluster_info, - unsigned long *zeromap) + struct swap_cluster_info *cluster_info) { spin_lock(&swap_lock); spin_lock(&si->lock); - setup_swap_info(si, prio, swap_map, cluster_info, zeromap); + setup_swap_info(si, prio, swap_map, cluster_info); spin_unlock(&si->lock); spin_unlock(&swap_lock); /* @@ -2329,7 +2326,7 @@ static void reinsert_swap_info(struct swap_info_struct *si) { spin_lock(&swap_lock); spin_lock(&si->lock); - setup_swap_info(si, si->prio, si->swap_map, si->cluster_info, si->zeromap); + setup_swap_info(si, si->prio, si->swap_map, si->cluster_info); _enable_swap_info(si); spin_unlock(&si->lock); spin_unlock(&swap_lock); @@ -2400,7 +2397,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) { struct swap_info_struct *p = NULL; unsigned char *swap_map; - unsigned long *zeromap; struct swap_cluster_info *cluster_info; struct file *swap_file, *victim; struct address_space *mapping; @@ -2495,8 +2491,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) p->swap_file = NULL; swap_map = p->swap_map; p->swap_map = NULL; - zeromap = p->zeromap; - p->zeromap = NULL; maxpages = p->max; cluster_info = p->cluster_info; p->max = 0; @@ -2508,7 +2502,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) kfree(p->global_cluster); p->global_cluster = NULL; vfree(swap_map); - kvfree(zeromap); free_cluster_info(cluster_info, maxpages); inode = mapping->host; @@ -2972,7 +2965,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) sector_t span; unsigned long maxpages; unsigned char *swap_map = NULL; - unsigned long *zeromap = NULL; struct swap_cluster_info *cluster_info = NULL; struct folio *folio = NULL; struct inode *inode = NULL; @@ -3078,17 +3070,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (error) goto bad_swap_unlock_inode; - /* - * Use kvmalloc_array instead of bitmap_zalloc as the allocation order might - * be above MAX_PAGE_ORDER incase of a large swap file. - */ - zeromap = kvmalloc_array(BITS_TO_LONGS(maxpages), sizeof(long), - GFP_KERNEL | __GFP_ZERO); - if (!zeromap) { - error = -ENOMEM; - goto bad_swap_unlock_inode; - } - if (si->bdev && bdev_stable_writes(si->bdev)) si->flags |= SWP_STABLE_WRITES; @@ -3155,7 +3136,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) prio = DEF_SWAP_PRIO; if (swap_flags & SWAP_FLAG_PREFER) prio = swap_flags & SWAP_FLAG_PRIO_MASK; - enable_swap_info(si, prio, swap_map, cluster_info, zeromap); + enable_swap_info(si, prio, swap_map, cluster_info); pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n", K(si->pages), name->name, si->prio, nr_extents, @@ -3183,7 +3164,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) si->flags = 0; spin_unlock(&swap_lock); vfree(swap_map); - kvfree(zeromap); if (cluster_info) free_cluster_info(cluster_info, maxpages); if (inced_nr_rotate_swap) -- 2.52.0