From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 D3CA1356A09 for ; Thu, 12 Mar 2026 02:38:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773283114; cv=none; b=jw/9ui5bV4R3Dcd0Gl7ROQdRkK+TBR8i8hA+Ke4plqN1Kp1S+EC0HzeQpoA1PIsKaa+EDyv5sRZRKujX1E1Oqi9wX8cNHMVP/xnlw50lweqX3lqijLlQgIrnwOsVRZko8e9mYs+OEy9yTM6v74KmRMu1PPhZawV+WAo2G+k7KPA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773283114; c=relaxed/simple; bh=ibTj7/ogzWNpT8G1KdOKKA2OkIgEQv1DtrkfMweq/BM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=taBMRyPPxdPSMxYnYOSOlydWgxE56TduW2MZUYDrQozP1Qx7YZZu/YW3OaKPuqSn440+fGX7pszChhTwFT91V7rKsb4GIlYhXZ/0VIVGuOcsBl9h61/Cj17x/tuVq3ix2za4fV2Yp0/DOhu4U6U5lkWd00AbrfE5p4Gjl4sxr6Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=HmObMdae; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=bywfVLu9; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HmObMdae"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="bywfVLu9" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773283112; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fHllJATiTNFut0Nwy3S3Va7raOdDGK8jrsU6m5odn3Q=; b=HmObMdaeWXz3dLAIYTQFOmkfAIAhLFH8r9Tzf+d8slq7ksDDHfIcREf0+8OWIQ852cUmai 0O3SFJoIhF0Z38PzrgLNSRhAblV6JHa17aid8EgRBXHR/eUy9sxA4QnzycgkhQXjbSJ2od 7kcVBosV85d7AharwnF/QO+y+UIvWm4= Received: from mail-pj1-f71.google.com (mail-pj1-f71.google.com [209.85.216.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-64-TYZA9S-wNJm30JaSnzuUhw-1; Wed, 11 Mar 2026 22:38:30 -0400 X-MC-Unique: TYZA9S-wNJm30JaSnzuUhw-1 X-Mimecast-MFC-AGG-ID: TYZA9S-wNJm30JaSnzuUhw_1773283110 Received: by mail-pj1-f71.google.com with SMTP id 98e67ed59e1d1-3594620fe97so3708966a91.1 for ; Wed, 11 Mar 2026 19:38:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1773283109; x=1773887909; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=fHllJATiTNFut0Nwy3S3Va7raOdDGK8jrsU6m5odn3Q=; b=bywfVLu9k4dDwDZbZElCEwx40abgkasYXEyTzEWmxpBhpyftf9qLUv/LuRv4TqmGBR zvY2Vmu1cpvtabxC1ciGUSIvZ9T91+MgNIf7KmNB/H7dGUgKt41OudCyRGQXf/aH6QDY B5FY/0+Y6Swl2yWI/VMCr38Osvjjih0ZxBt/yZ1omg32/OVQQEW/VpiOsV+Bve18njyw uqEXrv3JrE1jamvhFcTHhq3ptZgoGR4DlN0vjOvMbNIdv/Mszgd8ipzrix0GL10y8Y3T PpPikQrrS4/Q6zqoyGsZjx4glx2FgLQ1Z3Stimy1hw9wD4gVJCK53f7GtBOGmSMIzMCt aXCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773283109; x=1773887909; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=fHllJATiTNFut0Nwy3S3Va7raOdDGK8jrsU6m5odn3Q=; b=bFcoHqfvcXDySFaj5vj+BXIPMO0juJoV0i2RTvidulrvYYlyfLacqorga6gnCqos1z vCYO7MSPJo+mEj6b8MlyJWn49z2wFRHVPqUgCth/cwWYGj0Rl74sJG72ZqGXpnhlgXno YHUpTJZFf/LQFuAXbZw5ffH/79r+i5CHmzXeTyUvgmx7XMksK597KNxTsale92QrmigB SOy26dL7knJ3noNJUAUq/4hmrcLhUct5pT/e4AqviioYLReXLXV8rNTZtq0RSzVtTTUY fnx5E4EeuWU9eUIRWAwQzhCscQl2wdcB1S+i1k+l9RuEiON/qDNcmYDNUWCTj6WsEHRr 7t2A== X-Gm-Message-State: AOJu0YwoVUnCk/lgtQO166F4cKofcsvyqesRUXw5+y3lspVAuCo0+7PM bk9tbMz2wtcZzvWQP83Mjajxc1D36qF6viufTg6xnW6uYgxhpLMJ33P+HOPfJjD9vbK6ctCMnmL meMg+ilK1jMniS5XAtp0QLEFw2dtD0MK9aUt9YzVr0QW2Lkc98HDCC+/Lbtwg4oatGZt8Jw== X-Gm-Gg: ATEYQzwVlwg53PO9Q+ZEKYukZvPXAvKXF3bu5UZWE94fQ6x01jjJESAqUnrcGm/vJqi h+AuIBkOAG9EKZltBl8On6Uzj54wIAjJ9d2oU/KP4vlf6wNipa5l+4cddgdORXy3rvuP+AEYUA5 UTnKZpaFbBf3tLCY5bONVRJ+LXoFHV01E9adx2iokbZTy6dNXeAiBt3LLXKJfF0BtHRHZ3NLr8z kdjRi23kptwaDpiOZIpfeAQ+twW3vx2juo+Sb4/ME7T4kAHWAEGZaUi1k7uTqr8ADhAaJD+IXKN ZOZPIAVFRh9r6a4W06TwCkmpQJZFiBqFZaOaXeAI0OADgAdS+TWMyM3NAVanX4YjLrl+EN3etM+ fsWiF15MsRq3pKKiDgA== X-Received: by 2002:a17:90b:3d90:b0:356:282e:7eb7 with SMTP id 98e67ed59e1d1-35a0121eddemr4409712a91.12.1773283109567; Wed, 11 Mar 2026 19:38:29 -0700 (PDT) X-Received: by 2002:a17:90b:3d90:b0:356:282e:7eb7 with SMTP id 98e67ed59e1d1-35a0121eddemr4409694a91.12.1773283109239; Wed, 11 Mar 2026 19:38:29 -0700 (PDT) Received: from redhat.com ([209.132.188.88]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c73cdf0e99dsm3151428a12.7.2026.03.11.19.38.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 19:38:28 -0700 (PDT) Date: Thu, 12 Mar 2026 10:38:26 +0800 From: Li Wang To: Yosry Ahmed Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Johannes Weiner , Michal Hocko , Michal =?utf-8?Q?Koutn=C3=BD?= , Muchun Song , Nhat Pham , Tejun Heo , Roman Gushchin , Shakeel Butt Subject: Re: [PATCH 5/5] selftest/cgroup: fix zswap attempt_writeback() on 64K pagesize system Message-ID: References: <20260311110523.26624-1-liwang@redhat.com> <20260311110523.26624-5-liwang@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Mar 11, 2026 at 11:58:34AM -0700, Yosry Ahmed wrote: > On Wed, Mar 11, 2026 at 4:06 AM Li Wang wrote: > > > > In attempt_writeback(), a memsize of 4M only covers 64 pages on 64K > > page size systems. When memory.reclaim is called, the kernel prefers > > reclaiming clean file pages (binary, libc, linker, etc.) over swapping > > anonymous pages. With only 64 pages of anonymous memory, the reclaim > > target can be largely or entirely satisfied by dropping file pages, > > resulting in very few or zero anonymous pages being pushed into zswap. > > > > This causes zswap_usage to be extremely small or zero, making > > zswap_usage/2 insufficient to create meaningful writeback pressure. > > The test then fails because no writeback is triggered. > > > > On 4K page size systems this is not an issue because 4M covers 1024 > > pages, and file pages are a small fraction of the reclaim target. > > > > Scale memsize up to 64M on systems with page size larger than 4K, so > > that enough anonymous pages are allocated to reliably populate zswap > > and trigger writeback. The original 4M is kept for 4K page size systems > > to avoid unnecessary memory usage and test runtime. > > > > === Error Log === > > # uname -rm > > 6.12.0-211.el10.ppc64le ppc64le > > > > # getconf PAGESIZE > > 65536 > > > > # ./test_zswap > > TAP version 13 > > 1..7 > > ok 1 test_zswap_usage > > ok 2 test_swapin_nozswap > > ok 3 test_zswapin > > not ok 4 test_zswap_writeback_enabled > > ... > > > > Signed-off-by: Li Wang > > Cc: Johannes Weiner > > Cc: Michal Hocko > > Cc: Michal Koutný > > Cc: Muchun Song > > Cc: Nhat Pham > > Cc: Tejun Heo > > Cc: Roman Gushchin > > Cc: Shakeel Butt > > Cc: Yosry Ahmed > > --- > > tools/testing/selftests/cgroup/test_zswap.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c > > index 30d3fbf6b4fb..2d065184eea4 100644 > > --- a/tools/testing/selftests/cgroup/test_zswap.c > > +++ b/tools/testing/selftests/cgroup/test_zswap.c > > @@ -264,7 +264,7 @@ static int test_zswapin(const char *root) > > static int attempt_writeback(const char *cgroup, void *arg) > > { > > long pagesize = sysconf(_SC_PAGESIZE); > > - size_t memsize = MB(4); > > + size_t memsize = pagesize > 4096 ? MB(64): MB(4); > > pagesize << 10 or pagesize * 1024? Sure, I will go pagesize * 1024 which clearly shows the numbers of page. -- Regards, Li Wang