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Thu, 12 Mar 2026 04:07:09 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.57]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E2EA219560A6; Thu, 12 Mar 2026 04:07:03 +0000 (UTC) From: Li Wang To: mkoutny@suse.com, yosryahmed@google.com Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner , Michal Hocko , Muchun Song , Nhat Pham , Tejun Heo , Roman Gushchin , Shakeel Butt Subject: [PATCH v2 6/7] selftests/cgroup: replace hardcoded page size values in test_zswap Date: Thu, 12 Mar 2026 12:06:26 +0800 Message-ID: <20260312040627.55257-6-liwang@redhat.com> In-Reply-To: <20260312040627.55257-1-liwang@redhat.com> References: <20260312040627.55257-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: p6wXLF8Hva0cxv6MFJJZuZJR_RG-BXUjSfM1gt_hfU0_1773288429 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CE907180002 X-Stat-Signature: 7uf754z7qs1ajpq5t17py16tf99hbnc1 X-Rspam-User: X-HE-Tag: 1773288435-122477 X-HE-Meta: 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 0hru73vR 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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 | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 654874fb371b..4eb88930b45f 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; } @@ -83,7 +85,6 @@ static int allocate_and_read_bytes(const char *cgroup, void *arg) static int allocate_bytes(const char *cgroup, void *arg) { - long pagesize = sysconf(_SC_PAGESIZE); size_t size = (size_t)arg; char *mem = (char *)malloc(size); @@ -263,7 +264,6 @@ 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; @@ -416,7 +416,6 @@ static int test_zswap_writeback_disabled(const char *root) static int test_no_invasive_cgroup_shrink(const char *root) { int ret = KSFT_FAIL; - long pagesize = sysconf(_SC_PAGESIZE); size_t control_allocation_size = MB(64); char *control_allocation = NULL, *wb_group = NULL, *control_group = NULL; @@ -479,7 +478,7 @@ 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(); @@ -527,7 +526,7 @@ 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 */ @@ -554,7 +553,7 @@ 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); @@ -565,8 +564,8 @@ 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; @@ -622,6 +621,7 @@ int main(int argc, char **argv) char root[PATH_MAX]; int i, state; + 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