From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 AC1AA2989B5 for ; Fri, 13 Mar 2026 04:36:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773376590; cv=none; b=q0q1QShPiqn/+4B7XzpcCCmPVTETASEq9SFctWVZNrSdQDG8hV6JrMli6us/EGPbiHhAKU94okENgrR2vtgaAeh4KI4sIg2R4Qsbbc9iccgNHXb8akPUnSiawXHt74/Dt/yVvKSjLfN7JS22+66kRxVT6GdJh3UeZup0GWPlV2A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773376590; c=relaxed/simple; bh=cyX8co6QyO5W/TI++M94O1paixukgnvbYTZThdYZA54=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Hcr/9CUg2lImVBxlAkf7lAJgGoTq3Gt0NEbYHx7svJFtokfstL/af+uQ5uto5CVM5WOBWWNjH8A8W1F3xl9f02SiFQn7BLEvRn26xMjlOH80QRtpPWNCnHsm2wjEKF79Sz569KGmBJJsE1F1Sr5cbop4sP8PoRil4lrBRbGpmvo= 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=ikLpNGZ8; arc=none smtp.client-ip=170.10.129.124 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="ikLpNGZ8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773376587; 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=a11DWC4Nbs8vhuB0T8h/BbKreRPzDD33p5rwkRoyECU=; b=ikLpNGZ8csmvVuSIexSHtVMZB8n40Vx/1jCeld2ynUIAQY7kCrukpF4nT+1ft/o9bybH5P moNhSMgXilsslKVqGsqZAPSRiR2KUubvG1AD+/rbhGUfjcZeskmE4VeXSuopfr0c6V8MHa Dq6V/8EY/vSmQgJdzgcvJ0QyMuzYx0w= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-269-vGbx0mCMOMKZ5wwKmg4RuQ-1; Fri, 13 Mar 2026 00:36:23 -0400 X-MC-Unique: vGbx0mCMOMKZ5wwKmg4RuQ-1 X-Mimecast-MFC-AGG-ID: vGbx0mCMOMKZ5wwKmg4RuQ_1773376582 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A53721955E7B; Fri, 13 Mar 2026 04:36:21 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.18]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E680B19540C2; Fri, 13 Mar 2026 04:36:15 +0000 (UTC) From: Li Wang To: yosryahmed@google.com, nphamcs@gmail.com Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner , Michal Hocko , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Muchun Song , Tejun Heo , Roman Gushchin , Shakeel Butt , Yosry Ahmed Subject: [PATCH v3 7/7] selftest/cgroup: fix zswap attempt_writeback() on 64K pagesize system Date: Fri, 13 Mar 2026 12:35:32 +0800 Message-ID: <20260313043532.103987-7-liwang@redhat.com> In-Reply-To: <20260313043532.103987-1-liwang@redhat.com> References: <20260313043532.103987-1-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-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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. 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 page size systems. === 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 Acked-by: Yosry Ahmed --- Notes: v3: - No changes. v2: - use pagesize * 1024 which clearly shows the page numbers. 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 f84e84c3e7c8..d7a862a414e5 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -269,7 +269,7 @@ static int test_zswapin(const char *root) */ static int attempt_writeback(const char *cgroup, void *arg) { - size_t memsize = MB(4); + size_t memsize = pagesize * 1024; char buf[pagesize]; long zswap_usage; bool wb_enabled = *(bool *) arg; -- 2.53.0