From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f52.google.com (mail-ot1-f52.google.com [209.85.210.52]) (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 90FAA3BED7D for ; Thu, 6 Aug 2026 18:43:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786041798; cv=none; b=dpkuK1+IfTiN1xWRnwaDrZulNaYnAg/3N870DOX0QGGxQYTgX9GDgzhvIvdqvH6o4u3c273f9EBgM4UO3P7wSnC7HbJDOIPVP8U2lRNg6MA2rAGek/CVNjcrryCVB5NiPf4j+FyOovq6XOONbLGe4306D+cl5SpcDc3wm4YVCZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786041798; c=relaxed/simple; bh=SNocFtXa8C4f89zudX1FgBzt9ndc5ukWPrs95OuM/mQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s4YsxUGZ2fF/d9S5nA5ikgcYBMVHi1gFfZCjsReIFUGwAqgCHa4spHZUfoTJ8TmfRjlzOT2JXb+A7N9EqzckDszWzi0UVUbGD8GGbHK5qlIif+EqG4TwCjD6toZYof8trY7lmRKGroakTHTNMtYDnlh3DMA927St4gdarcUY3Ow= 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=MuH1RETk; arc=none smtp.client-ip=209.85.210.52 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="MuH1RETk" Received: by mail-ot1-f52.google.com with SMTP id 46e09a7af769-7e9ecd7216cso1520125a34.3 for ; Thu, 06 Aug 2026 11:43:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1786041795; x=1786646595; 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:content-type; bh=XJDCmTvRD2vNfT2YGrgT7EosXDcYWyreOqvvzwLRIg0=; b=MuH1RETknsQ10GggJCh/GIl5KRUeTQoyvhiynmsTumjN5IJUffOqFSkKZnIpjYj0cQ u1RDvCB2bOgy3Z9tskxkNhVwnL1MSHwVdzHTw/K3ERQwCOSCrIv9AodwhbFauOmomqnB hMhBGx4SW3pxoWHr/LDgu+ZxFS68ZZZLU/rRYW3/XE98N0EQabPCzLMzMBX/pUsvEvzm 92lQEoyrxpZu/+STMBMWEY9tI7LHKKc3n6m9hf1Wdw7CmXdFqXRjjoHLkR2zpKIEVj82 PiqRFN0vqTZ81SVYMmtiYOeV5SGt66blbMjzQuWsKQ0R7Om4Dpggzs7IDRDgO3hmaGZ2 uy5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786041795; x=1786646595; 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:content-type; bh=XJDCmTvRD2vNfT2YGrgT7EosXDcYWyreOqvvzwLRIg0=; b=dQ245yO+sfwDFa8GfEk7UosVVN1Qc30ungVjPXlfBd63Zzq27ABOBvLf652uBUF1pp HoZCHcZo9U7ZeeNhR6Or2BfjQNUssaF8aSt1XYrPVFnk3EMy4N8CdJPLPYdsVRPRS/dE TEdHC/EfNlGE5oJUKxj562PKrquLtCIr3V68GDrObpXca/qJGhahzuaPNT0Hp2gkQvfI PX06xl0TqA/0ygeWReUQu0IIlSOEUg17z3d5yIdt5TbunPnEru/pCyW5/7EsLLkbg1xi /gNlSvTS2yx6lQBDCxDBY2bcooevSYu7IZJtWtWWfUTQ1zYc8a1LjVCki1qHxRFNfkhI KBfg== X-Forwarded-Encrypted: i=1; AHgh+Rr0IAcszDCv7H+kqWCP8Tp59cZwVbc1fxzuSwx3SAwADL519ntZbw6EpvACTNd7GTi9uTToU0ZPlqV/Es8=@vger.kernel.org X-Gm-Message-State: AOJu0YyJEOcG7b39aGN4xqnd7UH0DBW8jUFwtbexvibLQaoyuuf0y9mW rkmRIhiE3lh4BBAWV/NTnaQl1YfZ5yzYEI6yqNlcDnETsFx3ie1cBsYI X-Gm-Gg: AR+sD114p4lQN1C7G9LKtekBGlWnhh/29ZyTuDlDn/My4OkkZPrgTtHcT3c91/WVM6u yHqk2hVBG657BWw/hUUkZfoJHzPAwLjrHPPYOILUaEacwUiHBC8I1Qalo2GW4z63lNXp3GkRnXv ZPf25105pKaPN0ZilpJfnwUePl+Q7f/9y47PnotiRfrheANAS9RuHFENGkT1ov53tvIy/xPDfA4 FJEr65BAkYh1PhamqnQtiMFmPGnh9m6s7yyHANECi35+hRNA1duqWs7BqT9ofRF3U8w4PjdfEwZ 9iI9PLYHRtqnkalB0nqSD35ifUOKkOyv90M7QCfu+29rl8rX4dBw6FpL/VrqEwmZz4mv/2J+7s8 cqoRn1cCIY8agKEVhjYd3M5q1R0US4x7DAlaqJIv0+7ReoHZriNpKzS7bCAA1BPGfKDLuBZObuF 5sTBwz+FDrBFGXiI6LMkKMOTf5mFc6nKlxEhWS1uqWLEDo1lscqGqzBrio2gwySLAeACxyv1yAH SOFKqZbGLME/t5RFVRjKyQ= X-Received: by 2002:a05:6830:6404:b0:7e9:ead3:4449 with SMTP id 46e09a7af769-7f1e5d0f423mr10084761a34.6.1786041790716; Thu, 06 Aug 2026 11:43:10 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:52::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7f1df5a4f9bsm5051028a34.23.2026.08.06.11.43.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 11:43:10 -0700 (PDT) From: Nhat Pham To: akpm@linux-foundation.org Cc: chrisl@kernel.org, kasong@tencent.com, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, yosry@kernel.org, david@kernel.org, muchun.song@linux.dev, shikemeng@huaweicloud.com, baoquan.he@linux.dev, baohua@kernel.org, youngjun.park@lge.com, chengming.zhou@linux.dev, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, qi.zheng@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, riel@surriel.com, gourry@gourry.net, haowenchao22@gmail.com, corbet@lwn.net, kernel-team@meta.com, nphamcs@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, cgroups@vger.kernel.org Subject: [PATCH v3 09/11] mm, swap: add debugfs counters for vswap Date: Thu, 6 Aug 2026 11:42:52 -0700 Message-ID: <20260806184254.3790858-10-nphamcs@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260806184254.3790858-1-nphamcs@gmail.com> References: <20260806184254.3790858-1-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: virtual swap slots (pages) currently allocated * alloc_reject: cumulative pages that failed to get a vswap slot Signed-off-by: Nhat Pham --- mm/swapfile.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 1a2d9d9625fc..b4d7af21ca1c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -133,6 +134,9 @@ 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 static int sysctl_vswap_enabled = IS_ENABLED(CONFIG_VSWAP_DEFAULT_ON); @@ -2056,11 +2060,13 @@ 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 @@ -2665,8 +2671,10 @@ 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 { @@ -4862,6 +4870,7 @@ static const struct ctl_table vswap_sysctls[] = { static int __init vswap_init(void) { struct swap_info_struct *si; + struct dentry *root; unsigned long maxpages; int err; @@ -4896,6 +4905,10 @@ static int __init vswap_init(void) register_sysctl_init("vm", vswap_sysctls); + 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