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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777003295; 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=Zo6kGfk/xM7DSaD4ymtNFmjwZMlQQ2mCHqeTEgtluNI=; b=q0CEzSKDXtzJ+NN/eB54JePXjXFiUxjo5CUbGCNwo7x2vx+fZA6OQor6AGPHWgmbp3WDpM bwZRvN7QGv/URDbOFDQAoJC3+Wcrx7bIkFp/Tcv3rNHqvwBK73BvhauXX8RMxCXnieELXz XsykdlZ2L6gcyo80CmMnESDt2xfM4E0= From: Li Wang To: 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, mkoutny@suse.com, shuah@kernel.org Cc: 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: [PATCH v7 2/8] selftests/cgroup: avoid OOM in test_swapin_nozswap Date: Fri, 24 Apr 2026 12:00:53 +0800 Message-ID: <20260424040059.12940-3-li.wang@linux.dev> In-Reply-To: <20260424040059.12940-1-li.wang@linux.dev> References: <20260424040059.12940-1-li.wang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 451761C000E X-Stat-Signature: yuo5jdzs37nn7afqgt8s4cfwe1zbhfou X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1777003297-899385 X-HE-Meta: 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 /XZz5SPB 2zncVxBZOaWRSxn3qDk2SaF29LZL/ATpAVzje6VNs6RjmoC61pUqGvUmO93ccd3cxr64MY2m7kLHtCptHV3oXSVbGM0mSTVPD8Sdm8xfFKDnxK8/cXXG52OmagtNWP4w9mIfzdD8bbOE8dHCOi8wzCoSSqfH2SS7dehniX8gnkC7QSmV34MguE+F/K9luzOZBGZh/7IOpfw/WEVAGJIXp+5cHAGu5v6liMa+WnYmI5X4SmklPTmsQ3Apztnp4/tx+6pL6iVAYfqwuF39WFGeGIsJsSG3vJQ/a2lt6WIvOvdjxEsfFpdietW5EuB7hChOO9oCStsJ3NYMym51szDWI6umYHfUWcf7aWPFDJya3ACKe3boifzlemJSThpDOmxGH26ocv8Q0wp4NWSLQhdHn+37k9Ut24oJYjrPgxX7PvvaSH1xQlieIMFitCm7Nj5gEBGg9 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 Acked-by: Nhat Pham --- 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 a94238a2e04..47709cbdcdf 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -165,21 +165,25 @@ 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 */ @@ -189,8 +193,9 @@ 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