From nobody Fri Apr 3 01:22:50 2026 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 44411273D6D for ; Thu, 2 Apr 2026 06:37:54 +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=1775111875; cv=none; b=cn2Dt0cKBLHDax1s8wpwoe6nyvnrPMqoB8dgmQlDYMH62xIB2kTpTNvWeZv5dnk1Keqvlv5uPNXaUBPOEJSspo7rQvYe50X/IkXaZflCARBajHv6qJiZyJeFSWDKd5BJ8GzLm2lsKgT7x+nzrcpbjKrSMRoZClIMKUJ6cq905VU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775111875; c=relaxed/simple; bh=uLblnqnPOBmm+nnz7vrkEG7ksJRWgoMyw6ikzXtoq00=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Qbyyn6IgPUthCj18LlxDhvR463ctGor8zMkFh5/DrJoddy1QxV+f1ghjTPcIkH1cXaaN6OwOceLWHJmdSmHUbDM0Nsf2Ij4ngxSpUHuERRQSnWIYRAskqXCeyOoPC+rpWAHcFAphLQYF3gAcb2wtxJjaVyMhBNADmO4lAgo3tY0= 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=gbUxmETb; 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="gbUxmETb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775111873; 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=oIeHjeE45sk83C/EEDWTFz2ktC6iYcZufl2nAkLE5aY=; b=gbUxmETbpTkN7TnorumzIK4ve6suy7K6CuyhSallkmYfx2gec/hIV73Shy0BraM/D+HnG2 5/oR4tHWOgSYK+qz9A6WYes/iuFREznTv/AxpiA9TQLJbWZOX0oOI2VnXOpdKweocsKPjS sLUDDVgVfrt+XYbQejpSw+3lwwJwBCg= Received: from mx-prod-mc-05.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-618-QHa-H3cXMe2HHTaWsDM1Qg-1; Thu, 02 Apr 2026 02:37:49 -0400 X-MC-Unique: QHa-H3cXMe2HHTaWsDM1Qg-1 X-Mimecast-MFC-AGG-ID: QHa-H3cXMe2HHTaWsDM1Qg_1775111866 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EFC8A195608E; Thu, 2 Apr 2026 06:37:45 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.158]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E65171800361; Thu, 2 Apr 2026 06:37:36 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, rppt@kernel.org, david@kernel.org, hannes@cmpxchg.org, yosry@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, mhocko@suse.com, shuah@kernel.org, chengming.zhou@linux.dev, longman@redhat.com, nphamcs@gmail.com Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Michal Hocko , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Muchun Song , Tejun Heo , Roman Gushchin , Shakeel Butt Subject: [PATCH v6 2/8] selftests/cgroup: avoid OOM in test_swapin_nozswap Date: Thu, 2 Apr 2026 14:37:08 +0800 Message-ID: <20260402063714.55124-3-liwang@redhat.com> In-Reply-To: <20260402063714.55124-1-liwang@redhat.com> References: <20260402063714.55124-1-liwang@redhat.com> 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 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 test_swapin_nozswap can hit OOM before reaching its assertions on some setups. The test currently sets memory.max=3D8M and then allocates/reads 32M with memory.zswap.max=3D0, which may over-constrain reclaim and kill the workload process. Replace hardcoded sizes with PAGE_SIZE-based values: - control_allocation_size =3D PAGE_SIZE * 512 - memory.max =3D control_allocation_size * 3 / 4 - minimum expected swap =3D control_allocation_size / 4 This keeps the test pressure model intact (allocate/read beyond memory.max = to force swap-in/out) while making it more robust across different environment= s. The test intent is unchanged: confirm that swapping occurs while zswap rema= ins unused when memory.zswap.max=3D0. =3D=3D=3D Error Logs =3D=3D=3D # ./test_zswap TAP version 13 1..7 ok 1 test_zswap_usage not ok 2 test_swapin_nozswap ... # dmesg [271641.879153] test_zswap invoked oom-killer: gfp_mask=3D0xcc0(GFP_KERNE= L), order=3D0, oom_score_adj=3D0 [271641.879168] CPU: 1 UID: 0 PID: 177372 Comm: test_zswap Kdump: loaded = Not tainted 6.12.0-211.el10.ppc64le #1 VOLUNTARY [271641.879171] Hardware name: IBM,9009-41A POWER9 (architected) 0x4e0202= 0xf000005 of:IBM,FW940.02 (UL940_041) hv:phyp pSeries [271641.879173] Call Trace: [271641.879174] [c00000037540f730] [c00000000127ec44] dump_stack_lvl+0x88= /0xc4 (unreliable) [271641.879184] [c00000037540f760] [c0000000005cc594] dump_header+0x5c/0x= 1e4 [271641.879188] [c00000037540f7e0] [c0000000005cb464] oom_kill_process+0x= 324/0x3b0 [271641.879192] [c00000037540f860] [c0000000005cbe48] out_of_memory+0x118= /0x420 [271641.879196] [c00000037540f8f0] [c00000000070d8ec] mem_cgroup_out_of_m= emory+0x18c/0x1b0 [271641.879200] [c00000037540f990] [c000000000713888] try_charge_memcg+0x= 598/0x890 [271641.879204] [c00000037540fa70] [c000000000713dbc] charge_memcg+0x5c/0= x110 [271641.879207] [c00000037540faa0] [c0000000007159f8] __mem_cgroup_charge= +0x48/0x120 [271641.879211] [c00000037540fae0] [c000000000641914] alloc_anon_folio+0x= 2b4/0x5a0 [271641.879215] [c00000037540fb60] [c000000000641d58] do_anonymous_page+0= x158/0x6b0 [271641.879218] [c00000037540fbd0] [c000000000642f8c] __handle_mm_fault+0= x4bc/0x910 [271641.879221] [c00000037540fcf0] [c000000000643500] handle_mm_fault+0x1= 20/0x3c0 [271641.879224] [c00000037540fd40] [c00000000014bba0] ___do_page_fault+0x= 1c0/0x980 [271641.879228] [c00000037540fdf0] [c00000000014c44c] hash__do_page_fault= +0x2c/0xc0 [271641.879232] [c00000037540fe20] [c0000000001565d8] do_hash_fault+0x128= /0x1d0 [271641.879236] [c00000037540fe50] [c000000000008be0] data_access_common_= virt+0x210/0x220 [271641.879548] Tasks state (memory values in pages): ... [271641.879550] [ pid ] uid tgid total_vm rss rss_anon rss_file= rss_shmem pgtables_bytes swapents oom_score_adj name [271641.879555] [ 177372] 0 177372 571 0 0 = 0 0 51200 96 0 test_zswap [271641.879562] oom-kill:constraint=3DCONSTRAINT_MEMCG,nodemask=3D(null),= cpuset=3D/,mems_allowed=3D0,oom_memcg=3D/no_zswap_test,task_memcg=3D/no_zsw= ap_test,task=3Dtest_zswap,pid=3D177372,uid=3D0 [271641.879578] Memory cgroup out of memory: Killed process 177372 (test_= zswap) total-vm:36544kB, anon-rss:0kB, file-rss:0kB, shmem-rss:0kB, UID:0 p= gtables:50kB oom_score_adj:0 Signed-off-by: Li Wang Cc: Johannes Weiner Cc: Michal Hocko Cc: Michal Koutn=C3=BD Cc: Muchun Song Cc: Nhat Pham Cc: Tejun Heo Cc: Roman Gushchin Cc: Shakeel Butt Acked-by: Yosry Ahmed Acked-by: Nhat Pham --- Notes: v4: - print the expected swap amount in KB but not MB. v3: - Replace fixed 8M/32M sizing with PAGE_SIZE-based sizing in test_swapin_nozswap. - Set memory.max to 3/4 of workload size to reduce OOM risk while still forcing reclaim/swap activity. - Derive minimum swap expectation from workload size (1/4) instead of a fixed 8M threshold. v2: - No change. tools/testing/selftests/cgroup/test_zswap.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/se= lftests/cgroup/test_zswap.c index 44fa81ef6157..ed257d464bd6 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -163,21 +163,25 @@ static int test_zswap_usage(const char *root) static int test_swapin_nozswap(const char *root) { int ret =3D KSFT_FAIL; - char *test_group; - long swap_peak, zswpout; + char *test_group, mem_max_buf[32]; + long swap_peak, zswpout, min_swap; + size_t allocation_size =3D sysconf(_SC_PAGESIZE) * 512; + + min_swap =3D allocation_size / 4; + snprintf(mem_max_buf, sizeof(mem_max_buf), "%zu", allocation_size * 3/4); =20 test_group =3D cg_name(root, "no_zswap_test"); if (!test_group) goto out; if (cg_create(test_group)) goto out; - if (cg_write(test_group, "memory.max", "8M")) + if (cg_write(test_group, "memory.max", mem_max_buf)) goto out; if (cg_write(test_group, "memory.zswap.max", "0")) goto out; =20 /* Allocate and read more than memory.max to trigger swapin */ - if (cg_run(test_group, allocate_and_read_bytes, (void *)MB(32))) + if (cg_run(test_group, allocate_and_read_bytes, (void *)allocation_size)) goto out; =20 /* Verify that pages are swapped out, but no zswap happened */ @@ -187,8 +191,9 @@ static int test_swapin_nozswap(const char *root) goto out; } =20 - if (swap_peak < MB(24)) { - ksft_print_msg("at least 24MB of memory should be swapped out\n"); + if (swap_peak < min_swap) { + ksft_print_msg("at least %ldKB of memory should be swapped out\n", + min_swap / 1024); goto out; } =20 --=20 2.53.0