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Sun, 22 Mar 2026 06:11:05 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.34]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 40AE31955F21; Sun, 22 Mar 2026 06:10:58 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, yosry@kernel.org, yosryahmed@google.com, 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 v4 2/7] selftests/cgroup: avoid OOM in test_swapin_nozswap Date: Sun, 22 Mar 2026 14:10:33 +0800 Message-ID: <20260322061038.156146-3-liwang@redhat.com> In-Reply-To: <20260322061038.156146-1-liwang@redhat.com> References: <20260322061038.156146-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: iI-RP7vUYuuXTVHJgLzH5fuh1n5HiVl4JvHc8mEV390_1774159865 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 05837C0004 X-Rspamd-Server: rspam07 X-Stat-Signature: 5nh18muhkxzgkguys98c3uriqjehbagt X-Rspam-User: X-HE-Tag: 1774159872-933450 X-HE-Meta: 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 Gye8wVz/ 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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 e69d845d3592..4481db4bc0f6 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -160,21 +160,25 @@ 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 control_allocation_size = sysconf(_SC_PAGESIZE) * 512; + + min_swap = control_allocation_size / 4; + snprintf(mem_max_buf, sizeof(mem_max_buf), "%zu", control_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 *)control_allocation_size)) goto out; /* Verify that pages are swapped out, but no zswap happened */ @@ -184,8 +188,9 @@ 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