From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) (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 DCA383FAE01 for ; Wed, 17 Jun 2026 12:26:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781699187; cv=none; b=VvxVkV1hAXALOUH2ManqiFHfSeqlq03n2cxxyllzIS0VSJY3f/s5wtYtyD3gtIbXo+covKXFUpxqbhVRhJ7x13/UPN/6rcP/2bGbUAqUbTwC2hLjOEnLOsoboYJjYA4A/xumZ6Y+B9Csb0ojiyXhJS7wNWUXBCSUzAkCQJCbP4E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781699187; c=relaxed/simple; bh=vb2jXE+X/Hf1iYoX+ZnlPTpxTVJexi7Tdbw9iGRH/60=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=udur0/8QZ6DjVEC1G7/SGZe6K5L0xUBfrPohMy53VlafKkt3Y9ZTQQDvzql3UQlqZ+YjAdcOPLUSQT6PcU+S67H2s3xHCVhlJt7xTgVClMrVlT7nRisKWvofAAvafdHMIbzALdaF7WXngGU334NI21fJFsB2Rdn/czBr9sn7oOM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=S8kdNCLy; arc=none smtp.client-ip=209.85.221.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="S8kdNCLy" Received: by mail-wr1-f43.google.com with SMTP id ffacd0b85a97d-4626fdc829aso626309f8f.3 for ; Wed, 17 Jun 2026 05:26:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1781699180; x=1782303980; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=Iim+7rfRj3+oRPn4MTff3Qg6MkJBVhCqBNuI2UP5kD8=; b=S8kdNCLyPKn+s/C3yKe+99tHMG1wxK3W0CExPbnzFNhctLvSxSxZIkz3E+Q19leuID LKowGszPlt7vhaSax2ZClyIxKUYNQS39nEWsZo3mhyLky3Oieg7wncOmM4CBMMNCmUPG BLv7lFCp6BcIdYhQtptxBP2Wpy2S9P58dfirMFyinbb9dbM7kz1TVpWU3kxm/O1/zM6C jP4GARok3jgF5OXRZrE7xRQitVwvbA+5eZLoAXzvfpIoHL1BxerJODs6z9tAEjXanQC3 97oWrBRrPNxxBDwLHKR1DxIVzSqHW5+tL3zs0UYg/5T4n/fa7JjQivb0s5iIvs3xgs3C A2RQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781699180; x=1782303980; h=in-reply-to: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=Iim+7rfRj3+oRPn4MTff3Qg6MkJBVhCqBNuI2UP5kD8=; b=RqJRHvh97RtQ784EKzGokr6TSVhrRA8g4QJDSLDp9lJ8zyxSykbs8RlnxSuQnrKR85 yc4tV2jeAWhox26xajQxlmHU+k/Q+RRovJbgKS5cYADKQKNObbRhL8dKwCIQNCJPaA+f hrHR7TVwrLNI7NNfYpQeZexVLfgXyrRQuvwDhTtnOjdHDP2dJnzPgHajm7k21UGrHdjL fJQWTdmo+3SS64Zanw2zsgDoZbBzeJTZ/M9lbO3tzln7srYLviZAZ4T2MiZly5kuzIU3 VxwU6/ThvioYbQrpWZlUvbH4KkEpfx9EHNCuaGTsmru57ZYEuBT3plLB6prC62rVXDTh H+Ag== X-Forwarded-Encrypted: i=1; AFNElJ/npZfr52e0ZbwwzAWKPsYz1RqVFkjNEB4QeJZ9YCkmkSWbDw8/MaYWsyTYjKFzDpFZ0xklK/KDFUaYWfM=@vger.kernel.org X-Gm-Message-State: AOJu0YzDFgBiV/hlcGCInng/WxQ+RYEd8vR8iTCbhc7Bg24eKq1UIdKQ nfYPSnk/IDwZn5slApO+ngcyeLm72tgMrAZB2TBwU/+2WFlKHy7I+S0gnIir6vm/uuc= X-Gm-Gg: AfdE7cl1p5KmDmJTH4M8AvReKtLKljdZB+jEmqs/uth+zRSTdUIjtv5d4Me7ug4RFsg hrvVkofzuMOaHffysIdEPe6c8wfEoxpxXfnbBmT1zexQKrBiKsBRTUupc20X/jFnsMhQcAv3nv5 +2kS1nSi5760XBHqKUU5Z4E6CbL+90pCvkjjcrTRNYO8BJJ6rI3XPa28W1uxnx1zWdF0BnDXpJd K8lssGRMxqRxvMm4mLXpVk5bGa1xjIsT23RvseSLbZ3tz9OISbFaXScuOeWjL/s6nHLRev7N69J O9l976Njw7ACJPSPfm/wnaET9JGQ8syJceyoSi//FrwcY72OGLmv8ClYJDtumKZMA3Tj/loSe1x vxOSMucO9Br65n44SBXEgovOqwVBD2HAONVqHNvGdUSwHBB4WB0doDxctjCPUibiScZIIHZL7QM Z1fRHRO1tQCHnydMDQtQ== X-Received: by 2002:a05:6000:46da:b0:461:a5a3:692e with SMTP id ffacd0b85a97d-4623f2e7e00mr4513543f8f.5.1781699179970; Wed, 17 Jun 2026 05:26:19 -0700 (PDT) Received: from localhost.localdomain ([62.77.90.70]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f2b0c10sm53060827f8f.21.2026.06.17.05.26.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 05:26:19 -0700 (PDT) Date: Wed, 17 Jun 2026 14:26:17 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Li Wang Cc: akpm@linux-foundation.org, tj@kernel.org, longman@redhat.com, roman.gushchin@linux.dev, hannes@cmpxchg.org, yosry@kernel.org, jiayuan.chen@linux.dev, nphamcs@gmail.com, chengming.zhou@linux.dev, shuah@kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Hocko , Muchun Song , Shakeel Butt Subject: Re: [PATCH v7 7/8] selftest/cgroup: fix zswap attempt_writeback() on 64K pagesize system Message-ID: References: <20260424040059.12940-1-li.wang@linux.dev> <20260424040059.12940-8-li.wang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="t4tngv5chqbx2jyz" Content-Disposition: inline In-Reply-To: <20260424040059.12940-8-li.wang@linux.dev> --t4tngv5chqbx2jyz Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v7 7/8] selftest/cgroup: fix zswap attempt_writeback() on 64K pagesize system MIME-Version: 1.0 On Fri, Apr 24, 2026 at 12:00:58PM +0800, 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. >=20 > This causes zswap_usage to be extremely small or zero, making > zswap_usage/4 insufficient to create meaningful writeback pressure. > The test then fails because no writeback is triggered. >=20 > 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. >=20 > Fix this by: > - Always allocating 1024 pages regardless of page size. This ensures > enough anonymous pages to reliably populate zswap and trigger > writeback, while keeping the original 4M allocation on 4K systems. > - Setting zswap.max to zswap_usage/4 instead of zswap_usage/2 to > create stronger writeback pressure, ensuring reclaim reliably > triggers writeback even on large page size systems. >=20 > =3D=3D=3D Error Log =3D=3D=3D > # uname -rm > 6.12.0-211.el10.ppc64le ppc64le >=20 > # getconf PAGESIZE > 65536 >=20 > # ./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 > ... >=20 > Signed-off-by: Li Wang > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Michal Koutn=FD > Cc: Muchun Song > Cc: Nhat Pham > Cc: Tejun Heo > Cc: Roman Gushchin > Cc: Shakeel Butt > Acked-by: Yosry Ahmed > Acked-by: Nhat Pham > --- > tools/testing/selftests/cgroup/test_zswap.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) Reviewed-by: Michal Koutn=FD --t4tngv5chqbx2jyz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCajKSZRsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQfj0C55Tb+Aho+AD/XAL/DakRMJXz9yk1Zazg v5ZtizO1OMSuDPj/gKs2+1sA/iTg96YzL1efNS85Rz0XMUIW3UE34U/bKW2+nSp8 /SII =BiG6 -----END PGP SIGNATURE----- --t4tngv5chqbx2jyz--