From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f41.google.com (mail-ot1-f41.google.com [209.85.210.41]) (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 6EB2C13DDA4 for ; Thu, 28 May 2026 21:30:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780003810; cv=none; b=QM8ypnB4QBYY3Odkbju6+6s14YL3nd36A5rMbz0rLE38XBxZj+eSlb8lfq3QmYHJOyFUrUuAXOG7gXIt+nPLg41GtNg13LytxZp3Af/jrqPvfccu4BNZk3F4tu+MoJIqmJoqIGVwZqHSzcC/jlLqvkP1y49nm7DDgOTrVcI4seU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780003810; c=relaxed/simple; bh=jiqdTPG4am84a711SHTa1ilvl5OD893KyijxO1MvI0o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SFTFUV+6a8Wfd/5pxWRCqhbUtE6n5tgrG1Hsy8hvn0SgoHwaIZwZ97HJzy0XaWsYGccKY6kIPD1UZ/v/1CeOZeyj8QpeeXOmB7JWRdS3fvEGV5J9nfHJzQ6EnSkaS/dnKCuY5OvNLF3dMQPPIolE0tjLhz57Vl8/QNV/pZDewDg= 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=LMXGI6YE; arc=none smtp.client-ip=209.85.210.41 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="LMXGI6YE" Received: by mail-ot1-f41.google.com with SMTP id 46e09a7af769-7e582b3bcaaso11226169a34.3 for ; Thu, 28 May 2026 14:30:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1780003806; x=1780608606; 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=L4CJlSs8AXl7ZfYRtAD893brHtGG85Zp/rm/ajAW6HQ=; b=LMXGI6YEeF0agqyES1/hpONwDszZp689VQZspTvH3yimMD9MIvK2saNzK4shirMYrW Q9iwtiKkXTG9cctkw2AE0Kt0/1e8lhO6x2g0csSBBVzCxXuA8vhcy6VTQ635WOm33PzS HLd09AuzuypPVkkUbv9ri+KKmgsZXLHJsdNakqfew/PZZBgVlsuX/GAr+LUvHFPuvii3 RQh4Fs8lzEYHHsa/F0qS7KFpgBaW6VmRKp4GNndic4Z5qauuNvMfPlslFN7Glv3FHej8 /Y9ev4XI0R6EGVX263hL7QGEHgEkg8UPYLkrZTqzvt1mdHFU87P2wk9zJtfB/C/8mobq f1dw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780003806; x=1780608606; 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=L4CJlSs8AXl7ZfYRtAD893brHtGG85Zp/rm/ajAW6HQ=; b=RbFyfEu57WIovPc2D9QULg88+r8uS5A3D5Ju2zk0VkkIp47BYH+xi/fsBnhHPohE+W uIAO0294So6tK8g+dXLaWREWwispm9hMkM9p8IkBnfkZUFCS9E+yQub0n9/YCR2Kw3Fa /k+2dR8h9esVmIToomneirGMXCQMxWbIROXqPXZHSl5ESx3aahZqyqyIfeVTRgd3flGT 5spL/J/Os3oPAHaVPsshNMNYmdIoj/0HSSXnC+YEXKFU9KzXAh2XFB73H0dzXzodiEdb pPz0ucKamsag+LQbvx8FypPxsk5CzvYhQPUojtHZAyQOO1635+eOtkLF1kmn2F04EI42 LzVQ== X-Forwarded-Encrypted: i=1; AFNElJ/RoH/MzaWheelhwSUF/njxJGtMSFTiiWFkacEqNmKqYDKyv3C52y30y0X7dq2LOZ986cbbjKPQjbkASuM=@vger.kernel.org X-Gm-Message-State: AOJu0YwT7obxMVzaVlqhUYfWnhYLWnWPEQ3Eb27gBQ9dl6yNpYUDWfoQ 83JUrMg0SM878PZoShsCxP93pH1CpYrFRW/sEVAGdInnexlx76YnxCkV X-Gm-Gg: Acq92OEK13uepR/8sTjyCCLW498ck4oyG4VEtr+8xO4UEVvjD1SvJk4rhyMPYqxD6Ra 1TcOMu/GWdR2FZcXEE9vuFMIORAzVW+n8z3qX4bonTMRa9W/8nvK5Gi+rvCxHDoP9afPS4b6sYA Nze85B/LC0jqKo3ihkbULHE3axCBOf0AIx0SARhfRjlBvLdyhgG9xiuHaFbXTT03zE2Txzczi3/ YjIZn1Xta6bgTvYZKfx4Uil3iw7Dl5T0lInEuXPp9VX/JZEjzPnI3Vk/XLh57KSR0PLkXe8z831 NEckj+6suYgZXgrK6ZRRPsHDL8U8GLo81TyiypDMtPjSOT3tTc1Dg6cNZ1Wx22ihxcUlt6yOsls 6BrMRBFJLABjVB0y+P1bqskM4HKMLW7IdDld2EYPdGkl3AxbSFm534Mh+SzJ7juE2ObOCIBslb7 t0U0Cf4Z9x8no2rjH1Qz+9I3Kf0vet8HxRGk1N52gZL8qQfl+pVzq8yAkD X-Received: by 2002:a05:6830:6314:b0:7dc:2f4f:17b4 with SMTP id 46e09a7af769-7e694fbdd5bmr187572a34.21.1780003806180; Thu, 28 May 2026 14:30:06 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:53::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7e6952991c2sm135613a34.26.2026.05.28.14.30.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 May 2026 14:30:05 -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: [RFC PATCH 5/5] mm, swap: add debugfs counters for vswap Date: Thu, 28 May 2026 14:29:29 -0700 Message-ID: <20260528212955.1912856-6-nphamcs@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260528212955.1912856-1-nphamcs@gmail.com> References: <20260528212955.1912856-1-nphamcs@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add /sys/kernel/debug/vswap/ with two counters: - used: number of virtual swap slots currently allocated - alloc_reject: cumulative count of failed vswap allocations Signed-off-by: Nhat Pham --- mm/swapfile.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index be901fb741e5..3740ab764405 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -132,6 +133,9 @@ static DEFINE_PER_CPU(struct percpu_swap_cluster, percpu_swap_cluster) = { .lock = INIT_LOCAL_LOCK(), }; +static atomic_t __maybe_unused vswap_used = ATOMIC_INIT(0); +static atomic_t __maybe_unused vswap_alloc_reject = ATOMIC_INIT(0); + #ifdef CONFIG_VSWAP struct percpu_vswap_cluster { unsigned long offset[SWAP_NR_ORDERS]; @@ -1993,11 +1997,13 @@ static bool vswap_alloc(struct folio *folio) if (folio_test_swapcache(folio)) { /* alloc_swap_scan_cluster updated percpu offset already */ local_unlock(&percpu_vswap_cluster.lock); + atomic_add(folio_nr_pages(folio), &vswap_used); return true; } this_cpu_write(percpu_vswap_cluster.offset[order], SWAP_ENTRY_INVALID); local_unlock(&percpu_vswap_cluster.lock); + atomic_add(folio_nr_pages(folio), &vswap_alloc_reject); return false; } #endif @@ -2554,8 +2560,10 @@ void __swap_cluster_free_entries(struct swap_info_struct *si, VM_WARN_ON(ci->count < nr_pages); - if (is_vswap) + if (is_vswap) { vswap_release_backing(ci, ci_start, nr_pages); + atomic_sub(nr_pages, &vswap_used); + } ci->count -= nr_pages; do { @@ -4793,6 +4801,7 @@ struct swap_info_struct *vswap_si; static int __init vswap_init(void) { struct swap_info_struct *si; + struct dentry *root; unsigned long maxpages; int err; @@ -4819,6 +4828,11 @@ static int __init vswap_init(void) mutex_unlock(&swapon_mutex); vswap_si = si; + + root = debugfs_create_dir("vswap", NULL); + debugfs_create_atomic_t("used", 0444, root, &vswap_used); + debugfs_create_atomic_t("alloc_reject", 0444, root, &vswap_alloc_reject); + pr_info("vswap: created virtual swap device (%lu pages)\n", maxpages); return 0; -- 2.53.0-Meta