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Thu, 26 Mar 2026 03:27:45 +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 A2EA61955D84; Thu, 26 Mar 2026 03:27:39 +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 5/8] selftests/cgroup: replace hardcoded page size values in test_zswap Date: Thu, 26 Mar 2026 11:26:55 +0800 Message-ID: <20260326032658.96819-6-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: dkUFiMUqN3-YjZQYbb-mx6hJbLh7unnZmhOofehFXtQ_1774495665 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: A071340005 X-Stat-Signature: qxe1uqk1swxdxe7bpran9uqbuz1znip6 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774495671-730160 X-HE-Meta: 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 zyEl0AYL 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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 Acked-by: Yosry Ahmed --- Notes: v5: - Change pagesize by the global page_size. v1-4: - No changes. tools/testing/selftests/cgroup/test_zswap.c | 39 ++++++++++++--------- 1 file changed, 22 insertions(+), 17 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 516da5d52bfd..fc7a9aa27e27 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 page_size; + #define PATH_ZSWAP "/sys/module/zswap" #define PATH_ZSWAP_ENABLED "/sys/module/zswap/parameters/enabled" @@ -71,11 +73,11 @@ 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 += page_size) 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 += page_size) { if (mem[i] != 'a') ret = -1; } @@ -91,7 +93,7 @@ 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 += page_size) mem[i] = 'a'; free(mem); return 0; @@ -270,9 +272,8 @@ 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]; + char buf[page_size]; long zswap_usage; bool wb_enabled = *(bool *) arg; int ret = -1; @@ -287,11 +288,11 @@ static int attempt_writeback(const char *cgroup, void *arg) * half empty, this will result in data that is still compressible * and ends up in zswap, with material zswap usage. */ - for (int i = 0; i < pagesize; i++) - buf[i] = i < pagesize/2 ? (char) i : 0; + for (int i = 0; i < page_size; i++) + buf[i] = i < page_size/2 ? (char) i : 0; - for (int i = 0; i < memsize; i += pagesize) - memcpy(&mem[i], buf, pagesize); + for (int i = 0; i < memsize; i += page_size) + memcpy(&mem[i], buf, page_size); /* Try and reclaim allocated memory */ if (cg_write_numeric(cgroup, "memory.reclaim", memsize)) { @@ -302,8 +303,8 @@ static int attempt_writeback(const char *cgroup, void *arg) zswap_usage = cg_read_long(cgroup, "memory.zswap.current"); /* zswpin */ - for (int i = 0; i < memsize; i += pagesize) { - if (memcmp(&mem[i], buf, pagesize)) { + for (int i = 0; i < memsize; i += page_size) { + if (memcmp(&mem[i], buf, page_size)) { ksft_print_msg("invalid memory\n"); goto out; } @@ -439,7 +440,7 @@ 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 += page_size) control_allocation[i] = 'a'; if (cg_read_key_long(control_group, "memory.stat", "zswapped") < 1) goto out; @@ -479,7 +480,7 @@ 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 += page_size) ((char *)allocation)[i] = 'a'; values->child_allocated = true; pause(); @@ -527,7 +528,7 @@ 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 / page_size; trigger_allocation_size = sys_info.totalram / 20; /* Set up test memcg */ @@ -554,7 +555,7 @@ 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 += page_size) trigger_allocation[i] = 'b'; usleep(100000); free(trigger_allocation); @@ -565,8 +566,8 @@ 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 * page_size - zswapped; + int result_ok = delta < stored_pages * page_size / 4; ret = result_ok ? KSFT_PASS : KSFT_FAIL; break; @@ -616,6 +617,10 @@ int main(int argc, char **argv) char root[PATH_MAX]; int i; + page_size = sysconf(_SC_PAGE_SIZE); + if (page_size <= 0) + page_size = BUF_SIZE; + ksft_print_header(); ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) -- 2.53.0