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Thu, 26 Mar 2026 03:27:25 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.83]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1CDCE1955D84; Thu, 26 Mar 2026 03:27:17 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, yosry@kernel.org, nphamcs@gmail.com, hannes@cmpxchg.org, mhocko@kernel.org, mkoutny@suse.com, muchun.song@linux.dev, tj@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev Cc: longman@redhat.com, liwang@redhat.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v5 2/8] selftests/cgroup: avoid OOM in test_swapin_nozswap Date: Thu, 26 Mar 2026 11:26:52 +0800 Message-ID: <20260326032658.96819-3-liwang@redhat.com> In-Reply-To: <20260326032658.96819-1-liwang@redhat.com> References: <20260326032658.96819-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: WPAAd_0SyHyiSLr6lahnzkoeRuEbQ4-ktXeJp-uQ9X4_1774495645 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: C8F5810000C X-Stat-Signature: myjcw8dx66ti1zghjstzccnuf4mnqnr3 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774495651-945318 X-HE-Meta: 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 96Ul5DxO 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: test_swapin_nozswap can hit OOM before reaching its assertions on some setups. The test currently sets memory.max=8M and then allocates/reads 32M with memory.zswap.max=0, which may over-constrain reclaim and kill the workload process. Replace hardcoded sizes with PAGE_SIZE-based values: - control_allocation_size = PAGE_SIZE * 512 - memory.max = control_allocation_size * 3 / 4 - minimum expected swap = 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 environments. The test intent is unchanged: confirm that swapping occurs while zswap remains unused when memory.zswap.max=0. === Error Logs === # ./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=0xcc0(GFP_KERNEL), order=0, oom_score_adj=0 [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/0x1e4 [271641.879188] [c00000037540f7e0] [c0000000005cb464] oom_kill_process+0x324/0x3b0 [271641.879192] [c00000037540f860] [c0000000005cbe48] out_of_memory+0x118/0x420 [271641.879196] [c00000037540f8f0] [c00000000070d8ec] mem_cgroup_out_of_memory+0x18c/0x1b0 [271641.879200] [c00000037540f990] [c000000000713888] try_charge_memcg+0x598/0x890 [271641.879204] [c00000037540fa70] [c000000000713dbc] charge_memcg+0x5c/0x110 [271641.879207] [c00000037540faa0] [c0000000007159f8] __mem_cgroup_charge+0x48/0x120 [271641.879211] [c00000037540fae0] [c000000000641914] alloc_anon_folio+0x2b4/0x5a0 [271641.879215] [c00000037540fb60] [c000000000641d58] do_anonymous_page+0x158/0x6b0 [271641.879218] [c00000037540fbd0] [c000000000642f8c] __handle_mm_fault+0x4bc/0x910 [271641.879221] [c00000037540fcf0] [c000000000643500] handle_mm_fault+0x120/0x3c0 [271641.879224] [c00000037540fd40] [c00000000014bba0] ___do_page_fault+0x1c0/0x980 [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=CONSTRAINT_MEMCG,nodemask=(null),cpuset=/,mems_allowed=0,oom_memcg=/no_zswap_test,task_memcg=/no_zswap_test,task=test_zswap,pid=177372,uid=0 [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 pgtables:50kB oom_score_adj:0 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: 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/selftests/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 = 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 = sysconf(_SC_PAGESIZE) * 512; + + min_swap = allocation_size / 4; + snprintf(mem_max_buf, sizeof(mem_max_buf), "%zu", allocation_size * 3/4); test_group = 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; /* 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; /* Verify that pages are swapped out, but no zswap happened */ @@ -187,8 +191,9 @@ static int test_swapin_nozswap(const char *root) goto out; } - 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; } -- 2.53.0