From nobody Thu Dec 25 01:47:02 2025 Received: from out-175.mta1.migadu.com (out-175.mta1.migadu.com [95.215.58.175]) (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 2E695626C9 for ; Thu, 1 Feb 2024 15:50:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.175 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706802635; cv=none; b=nS/wLUCLJTAfxN/omllxJyRrb0qECwyGOR+mmjBDW+61Q2FlfT5PsLhWK1bedL8ZMrAyNgy+YqE0KFfBvSbKayuyr42mrziNFAobM0GUlkAXYSyK26TErSeFzw5odIFdYBSbTfM83MaSz4w/UVfvCdtLhh70LAzYJemTvI+w6lY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706802635; c=relaxed/simple; bh=J1uE4pWFkFDvS8emS66Pzl+FOQ1T7dXIIEbsITHmLoY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=S0AYtfpgTShW5HPdpajPDCUV/P8OI4V9yh5jMV/ilFWLswMLZllGnexwyl6Gf1e795sh8mXeVpYvhKWskEHJdp/RQLAJHHirZPOoZn4WQLZXz/Z3/4iDmKg5Lu0knX5+YsrtlleMM7pgYs9Hzmz6WNH2Jhodo7kHhjh9el2V1VI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=bytedance.com; spf=pass smtp.mailfrom=linux.dev; arc=none smtp.client-ip=95.215.58.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=bytedance.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou Date: Thu, 01 Feb 2024 15:49:04 +0000 Subject: [PATCH 4/6] mm/zswap: remove duplicate_entry debug value Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20240201-b4-zswap-invalidate-entry-v1-4-56ed496b6e55@bytedance.com> References: <20240201-b4-zswap-invalidate-entry-v1-0-56ed496b6e55@bytedance.com> In-Reply-To: <20240201-b4-zswap-invalidate-entry-v1-0-56ed496b6e55@bytedance.com> To: Nhat Pham , Johannes Weiner , Andrew Morton , Yosry Ahmed Cc: linux-kernel@vger.kernel.org, Yosry Ahmed , Chengming Zhou , Johannes Weiner , linux-mm@kvack.org X-Migadu-Flow: FLOW_OUT cat /sys/kernel/debug/zswap/duplicate_entry 2086447 When testing, the duplicate_entry value is very high, but no warning message in the kernel log. From the comment of duplicate_entry "Duplicate store was encountered (rare)", it seems something goes wrong. Actually it's incremented in the beginning of zswap_store(), which found its zswap entry has already on the tree. And this is a normal case, since the folio could leave zswap entry on the tree after swapin, later it's dirtied and swapout/zswap_store again, found its original zswap entry. (Maybe we can reuse it instead of invalidating it?) So duplicate_entry should be only incremented in the real bug case, which already have "WARN_ON(1)", it looks redundant to count bug case, so this patch just remove it. Signed-off-by: Chengming Zhou Acked-by: Johannes Weiner Acked-by: Yosry Ahmed Reviewed-by: Nhat Pham --- mm/zswap.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 4381b7a2d4d6..3fbb7e2c8b8d 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -71,8 +71,6 @@ static u64 zswap_reject_compress_poor; static u64 zswap_reject_alloc_fail; /* Store failed because the entry metadata could not be allocated (rare) */ static u64 zswap_reject_kmemcache_fail; -/* Duplicate store was encountered (rare) */ -static u64 zswap_duplicate_entry; =20 /* Shrinker work queue */ static struct workqueue_struct *shrink_wq; @@ -1571,10 +1569,8 @@ bool zswap_store(struct folio *folio) */ spin_lock(&tree->lock); entry =3D zswap_rb_search(&tree->rbroot, offset); - if (entry) { + if (entry) zswap_invalidate_entry(tree, entry); - zswap_duplicate_entry++; - } spin_unlock(&tree->lock); objcg =3D get_obj_cgroup_from_folio(folio); if (objcg && !obj_cgroup_may_zswap(objcg)) { @@ -1661,7 +1657,6 @@ bool zswap_store(struct folio *folio) */ while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) =3D=3D -EEXIST) { WARN_ON(1); - zswap_duplicate_entry++; zswap_invalidate_entry(tree, dupentry); } if (entry->length) { @@ -1822,8 +1817,6 @@ static int zswap_debugfs_init(void) zswap_debugfs_root, &zswap_reject_compress_poor); debugfs_create_u64("written_back_pages", 0444, zswap_debugfs_root, &zswap_written_back_pages); - debugfs_create_u64("duplicate_entry", 0444, - zswap_debugfs_root, &zswap_duplicate_entry); debugfs_create_u64("pool_total_size", 0444, zswap_debugfs_root, &zswap_pool_total_size); debugfs_create_atomic_t("stored_pages", 0444, --=20 b4 0.10.1