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Sun, 22 Mar 2026 06:11:26 +0000 (UTC) Received: from fedora-laptop-x1.redhat.com (unknown [10.72.112.34]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4B19C1955F21; Sun, 22 Mar 2026 06:11:19 +0000 (UTC) From: Li Wang To: akpm@linux-foundation.org, yosry@kernel.org, yosryahmed@google.com, 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 v4 5/7] selftests/cgroup: replace hardcoded page size values in test_zswap Date: Sun, 22 Mar 2026 14:10:36 +0800 Message-ID: <20260322061038.156146-6-liwang@redhat.com> In-Reply-To: <20260322061038.156146-1-liwang@redhat.com> References: <20260322061038.156146-1-liwang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: 9gudENTiTmBbw42ugsdxp4fya1RdWwEi5IGfbBNfQss_1774159886 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 9215BC0004 X-Stat-Signature: oawu3cn8nkndeqdausbe1of8indeszf9 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1774159891-981271 X-HE-Meta: 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 l0WnH1Ci dARxIUkDysCwlnrKzhBMYGBWKbdJqYiUrA2L9YwWLnxxR2TbBB5YsFKnojyOlIPWXcjbZmmoXCOd9c+aWHB8JeQWJ2bjKiaAezqhjvJLbDx9EvFAY2esNh06FrQAES6SMfdcyu0Y6DtuUpHrXUfl0pclfXopl17R3jVtP3Ony7C+BBWL8jJESq+VZIVIzTOq/vkCIXkEQXGXk0NytL+grkLiAKItdVFkoztOxYOknAVI8ydaxr9M6eLzR1YdRnGH7IsLwlceubSiL6RKwuURQe1yEY+cLi/H/DwJRvkGC16ukJyi1/CEBFKzhoT5w6QhBV5Pgzw1zCkbgOHLbN0Yx2VjjJsph4JngoClqHeWwGcXvCDbuuApuCYp+8p4CO5wQ8bS+AKefJ/QQVc2IW4qLpw0gy/dhDVc689ESCE9X/SBQQtC+ljqPkXyd3fBKBF38J21equDstITNirR/AXgDxRvuOQHu0yV/Co3vyNyAkCD2n8bS3pnsDGU2xYhTu4Y7fe+sx7w2lb9fYrL9tbGPXJERd+r4Ixxqv18GRV2frf2GomzZWY/TXWcJHQZA3eRP0i0WSz/3O+55xbws8dpE5iev4ovFGAHRimHT 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 4982e8c4759c..407cfb6ae34d 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