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Fri, 13 Mar 2026 04:36:09 +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 ADF2319540C2; Fri, 13 Mar 2026 04:36:03 +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 Subject: [PATCH v3 5/7] selftests/cgroup: replace hardcoded page size values in test_zswap Date: Fri, 13 Mar 2026 12:35:30 +0800 Message-ID: <20260313043532.103987-5-liwang@redhat.com> In-Reply-To: <20260313043532.103987-1-liwang@redhat.com> References: <20260313043532.103987-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: 7P2e06OWMHexRD_wBPtpZSc1-IoxswaEFs_TLK7cD9Y_1773376569 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: C0DD8C000F X-Stat-Signature: j66sdo7j1y17rs9q586xdejodq47op5h X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773376575-493496 X-HE-Meta: U2FsdGVkX19ILY01GsjGLsaKtJRMeKsBhiNxI+rLMTBG6zMBUvDRNp8vKGWUnAURDLp+0VJUmgZhvnYPjsyTWlKlgZYnf+W0tCv1R8emDkH2hKfATYcthP9JQ+cYNo9L/Tx4fANAAhEtA9YOhudTIL+2tnZGiBlYeq/ezFMnLLXWTRD9o8roRYIbzZJSkGymcANYDdUqvASJXoHZ4KL9Iet3RyoTD56R3VMHgywnD5z39h2ub5gLyKAo+DQA6HiyJ3RLlvLFqYI8hLeutVRk95ZGCQTJU0f8h5eNxQC6sLcD35sVhH3iUHZp699BqqKiPb+zUHm1LQPU2adGlQAUtJg1oJK0XokYmFM6rVoRH4nYTcx3bDNtaCLhdQ8H4IcQhfbm0EEO8c3Fw3CsFM+F1cgtFbb6LmDohnKtd/unynX5kB2BSKQpggOkp2X8ySSPzjHuybGdqzT3YDo0dgCo81BHHbNnUAH2ExCNL4YvdYKsK/hHHj1Dzop/kWNgasvcj/SNepPGQiqVbuSd4wp1vfIqnXOQVwAWfV3CFCMKKkhgBBbaS7yZ7HRFH1FasdOhncLlW+BXwlfXM+i56FWY9x58aJWQ0+qKb+X+Lk2ZvJPe1CnFihQHQniYk3sFNMtEBDoq/qqg5G4jGtYEQm/VeJcEC3/iW87wLHfRHXbVqxTT1ipVp12gyYXPM61O1fVR1Tu4QDvxrexp0C3JkI872oRScggyvsR+DyAUJym0M5lzYoYnwfdGKltvzZesEkz3XDueuql4eT18boJT0bclkvPBpGrzOErKm923PL0HZuAJXuVV0GJNOXkELP058f7Q9y2Zwat6AoOKH4ZTVFDhfyKSj1Q63ks6z0nWVePmzxKR3z1UaaB4ho3klv7DftfFosvnEZtIDmyp8BmxoJdUcbCEgm2uwjwKM8cIBCs1Su8cfR6iW0jnNesWG9H/x3OSTdqKqPeCrXAYjyA1EvX zHFhY9Ao 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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_zswap uses hardcoded values of 4095 and 4096 throughout as page stride and page size, which are only correct on systems with a 4K page size. On architectures with larger pages (e.g., 64K on arm64 or ppc64), these constants cause memory to be touched at sub-page granularity, leading to inefficient access patterns and incorrect page count calculations, which can cause test failures. Replace all hardcoded 4095 and 4096 values with a global pagesize variable initialized from sysconf(_SC_PAGESIZE) at startup, and remove the redundant local sysconf() calls scattered across individual functions. No functional change on 4K page size systems. 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 Cc: Yosry Ahmed --- tools/testing/selftests/cgroup/test_zswap.c | 22 +++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 74b57331cbf1..cf5b1531c827 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -13,6 +13,8 @@ #include "kselftest.h" #include "cgroup_util.h" +static size_t pagesize; + static int read_int(const char *path, size_t *value) { FILE *file; @@ -68,11 +70,11 @@ static int allocate_and_read_bytes(const char *cgroup, void *arg) if (!mem) return -1; - for (int i = 0; i < size; i += 4095) + for (int i = 0; i < size; i += pagesize) mem[i] = 'a'; /* Go through the allocated memory to (z)swap in and out pages */ - for (int i = 0; i < size; i += 4095) { + for (int i = 0; i < size; i += pagesize) { if (mem[i] != 'a') ret = -1; } @@ -88,7 +90,7 @@ static int allocate_bytes(const char *cgroup, void *arg) if (!mem) return -1; - for (int i = 0; i < size; i += 4095) + for (int i = 0; i < size; i += pagesize) mem[i] = 'a'; free(mem); return 0; @@ -267,7 +269,6 @@ static int test_zswapin(const char *root) */ static int attempt_writeback(const char *cgroup, void *arg) { - long pagesize = sysconf(_SC_PAGESIZE); size_t memsize = MB(4); char buf[pagesize]; long zswap_usage; @@ -436,7 +437,7 @@ static int test_no_invasive_cgroup_shrink(const char *root) if (cg_enter_current(control_group)) goto out; control_allocation = malloc(control_allocation_size); - for (int i = 0; i < control_allocation_size; i += 4095) + for (int i = 0; i < control_allocation_size; i += pagesize) control_allocation[i] = 'a'; if (cg_read_key_long(control_group, "memory.stat", "zswapped") < 1) goto out; @@ -476,7 +477,7 @@ static int no_kmem_bypass_child(const char *cgroup, void *arg) values->child_allocated = true; return -1; } - for (long i = 0; i < values->target_alloc_bytes; i += 4095) + for (long i = 0; i < values->target_alloc_bytes; i += pagesize) ((char *)allocation)[i] = 'a'; values->child_allocated = true; pause(); @@ -524,7 +525,7 @@ static int test_no_kmem_bypass(const char *root) min_free_kb_low = sys_info.totalram / 500000; values->target_alloc_bytes = (sys_info.totalram - min_free_kb_high * 1000) + sys_info.totalram * 5 / 100; - stored_pages_threshold = sys_info.totalram / 5 / 4096; + stored_pages_threshold = sys_info.totalram / 5 / pagesize; trigger_allocation_size = sys_info.totalram / 20; /* Set up test memcg */ @@ -551,7 +552,7 @@ static int test_no_kmem_bypass(const char *root) if (!trigger_allocation) break; - for (int i = 0; i < trigger_allocation_size; i += 4095) + for (int i = 0; i < trigger_allocation_size; i += pagesize) trigger_allocation[i] = 'b'; usleep(100000); free(trigger_allocation); @@ -562,8 +563,8 @@ static int test_no_kmem_bypass(const char *root) /* If memory was pushed to zswap, verify it belongs to memcg */ if (stored_pages > stored_pages_threshold) { int zswapped = cg_read_key_long(test_group, "memory.stat", "zswapped "); - int delta = stored_pages * 4096 - zswapped; - int result_ok = delta < stored_pages * 4096 / 4; + int delta = stored_pages * pagesize - zswapped; + int result_ok = delta < stored_pages * pagesize / 4; ret = result_ok ? KSFT_PASS : KSFT_FAIL; break; @@ -616,6 +617,7 @@ int main(int argc, char **argv) char root[PATH_MAX]; int i; + pagesize = sysconf(_SC_PAGESIZE); ksft_print_header(); ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) -- 2.53.0