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Thu, 2 Apr 2026 06:38:15 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.158]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B2A691800351; Thu, 2 Apr 2026 06:38:06 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, rppt@kernel.org, david@kernel.org, hannes@cmpxchg.org, yosry@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, mhocko@suse.com, shuah@kernel.org, chengming.zhou@linux.dev, longman@redhat.com, nphamcs@gmail.com Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Michal Hocko , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Muchun Song , Tejun Heo , Roman Gushchin , Shakeel Butt Subject: [PATCH v6 5/8] selftests/cgroup: replace hardcoded page size values in test_zswap Date: Thu, 2 Apr 2026 14:37:11 +0800 Message-ID: <20260402063714.55124-6-liwang@redhat.com> In-Reply-To: <20260402063714.55124-1-liwang@redhat.com> References: <20260402063714.55124-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: LynSUFwmrXH27vaL6b2t3nZmDb_cw4efzwd5tzcgfSg_1775111895 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: tfd8sxy5iej6hk8esnbytnx98ioj9i65 X-Rspamd-Queue-Id: 2300D20007 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775111901-457550 X-HE-Meta: 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 VfFkicDN 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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: v6: - Use page_size replace the sysconf(_SC_PAGE_SIZE). v5: - Change pagesize by the global page_size. v1-4: - No changes. tools/testing/selftests/cgroup/test_zswap.c | 43 ++++++++++++--------- 1 file changed, 24 insertions(+), 19 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 516da5d52bfd..db4889bef6d4 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 int 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; @@ -165,7 +167,7 @@ static int test_swapin_nozswap(const char *root) int ret = KSFT_FAIL; char *test_group, mem_max_buf[32]; long swap_peak, zswpout, min_swap; - size_t allocation_size = sysconf(_SC_PAGESIZE) * 512; + size_t allocation_size = page_size * 512; min_swap = allocation_size / 4; snprintf(mem_max_buf, sizeof(mem_max_buf), "%zu", allocation_size * 3/4); @@ -243,7 +245,7 @@ static int test_zswapin(const char *root) goto out; } - if (zswpin < MB(24) / sysconf(_SC_PAGESIZE)) { + if (zswpin < MB(24) / page_size) { ksft_print_msg("at least 24MB should be brought back from zswap\n"); goto out; } @@ -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