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Yunsheng Linkuba-moo
Yunsheng Lin
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kuba-moo
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mm: page_frag: add a test module for page_frag
The testing is done by ensuring that the fragment allocated from a frag_frag_cache instance is pushed into a ptr_ring instance in a kthread binded to a specified cpu, and a kthread binded to a specified cpu will pop the fragment from the ptr_ring and free the fragment. CC: Andrew Morton <[email protected]> CC: Linux-MM <[email protected]> Signed-off-by: Yunsheng Lin <[email protected]> Reviewed-by: Alexander Duyck <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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‎tools/testing/selftests/mm/Makefile

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@@ -36,6 +36,8 @@ MAKEFLAGS += --no-builtin-rules
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CFLAGS = -Wall -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
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LDLIBS = -lrt -lpthread -lm
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TEST_GEN_MODS_DIR := page_frag
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TEST_GEN_FILES = cow
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TEST_GEN_FILES += compaction_test
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TEST_GEN_FILES += gup_longterm
@@ -126,6 +128,7 @@ TEST_FILES += test_hmm.sh
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TEST_FILES += va_high_addr_switch.sh
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TEST_FILES += charge_reserved_hugetlb.sh
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TEST_FILES += hugetlb_reparenting_test.sh
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TEST_FILES += test_page_frag.sh
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# required by charge_reserved_hugetlb.sh
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TEST_FILES += write_hugetlb_memory.sh

‎tools/testing/selftests/mm/page_frag/Makefile

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@@ -0,0 +1,18 @@
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PAGE_FRAG_TEST_DIR := $(realpath $(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
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KDIR ?= $(abspath $(PAGE_FRAG_TEST_DIR)/../../../../..)
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ifeq ($(V),1)
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Q =
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else
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Q = @
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endif
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MODULES = page_frag_test.ko
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obj-m += page_frag_test.o
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all:
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+$(Q)make -C $(KDIR) M=$(PAGE_FRAG_TEST_DIR) modules
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clean:
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+$(Q)make -C $(KDIR) M=$(PAGE_FRAG_TEST_DIR) clean

‎tools/testing/selftests/mm/page_frag/page_frag_test.c

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@@ -0,0 +1,198 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Test module for page_frag cache
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*
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* Copyright (C) 2024 Yunsheng Lin <[email protected]>
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*/
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/cpumask.h>
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#include <linux/completion.h>
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#include <linux/ptr_ring.h>
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#include <linux/kthread.h>
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#define TEST_FAILED_PREFIX "page_frag_test failed: "
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static struct ptr_ring ptr_ring;
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static int nr_objs = 512;
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static atomic_t nthreads;
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static struct completion wait;
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static struct page_frag_cache test_nc;
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static int test_popped;
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static int test_pushed;
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static bool force_exit;
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static int nr_test = 2000000;
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module_param(nr_test, int, 0);
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MODULE_PARM_DESC(nr_test, "number of iterations to test");
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static bool test_align;
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module_param(test_align, bool, 0);
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MODULE_PARM_DESC(test_align, "use align API for testing");
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static int test_alloc_len = 2048;
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module_param(test_alloc_len, int, 0);
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MODULE_PARM_DESC(test_alloc_len, "alloc len for testing");
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static int test_push_cpu;
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module_param(test_push_cpu, int, 0);
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MODULE_PARM_DESC(test_push_cpu, "test cpu for pushing fragment");
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static int test_pop_cpu;
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module_param(test_pop_cpu, int, 0);
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MODULE_PARM_DESC(test_pop_cpu, "test cpu for popping fragment");
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static int page_frag_pop_thread(void *arg)
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{
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struct ptr_ring *ring = arg;
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pr_info("page_frag pop test thread begins on cpu %d\n",
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smp_processor_id());
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while (test_popped < nr_test) {
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void *obj = __ptr_ring_consume(ring);
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if (obj) {
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test_popped++;
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page_frag_free(obj);
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} else {
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if (force_exit)
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break;
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cond_resched();
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}
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}
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if (atomic_dec_and_test(&nthreads))
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complete(&wait);
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pr_info("page_frag pop test thread exits on cpu %d\n",
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smp_processor_id());
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return 0;
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}
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static int page_frag_push_thread(void *arg)
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{
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struct ptr_ring *ring = arg;
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pr_info("page_frag push test thread begins on cpu %d\n",
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smp_processor_id());
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while (test_pushed < nr_test && !force_exit) {
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void *va;
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int ret;
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if (test_align) {
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va = page_frag_alloc_align(&test_nc, test_alloc_len,
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GFP_KERNEL, SMP_CACHE_BYTES);
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if ((unsigned long)va & (SMP_CACHE_BYTES - 1)) {
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force_exit = true;
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WARN_ONCE(true, TEST_FAILED_PREFIX "unaligned va returned\n");
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}
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} else {
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va = page_frag_alloc(&test_nc, test_alloc_len, GFP_KERNEL);
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}
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if (!va)
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continue;
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ret = __ptr_ring_produce(ring, va);
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if (ret) {
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page_frag_free(va);
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cond_resched();
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} else {
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test_pushed++;
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}
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}
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pr_info("page_frag push test thread exits on cpu %d\n",
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smp_processor_id());
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if (atomic_dec_and_test(&nthreads))
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complete(&wait);
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return 0;
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}
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static int __init page_frag_test_init(void)
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{
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struct task_struct *tsk_push, *tsk_pop;
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int last_pushed = 0, last_popped = 0;
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ktime_t start;
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u64 duration;
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int ret;
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test_nc.va = NULL;
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atomic_set(&nthreads, 2);
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init_completion(&wait);
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if (test_alloc_len > PAGE_SIZE || test_alloc_len <= 0 ||
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!cpu_active(test_push_cpu) || !cpu_active(test_pop_cpu))
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return -EINVAL;
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ret = ptr_ring_init(&ptr_ring, nr_objs, GFP_KERNEL);
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if (ret)
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return ret;
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tsk_push = kthread_create_on_cpu(page_frag_push_thread, &ptr_ring,
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test_push_cpu, "page_frag_push");
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if (IS_ERR(tsk_push))
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return PTR_ERR(tsk_push);
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tsk_pop = kthread_create_on_cpu(page_frag_pop_thread, &ptr_ring,
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test_pop_cpu, "page_frag_pop");
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if (IS_ERR(tsk_pop)) {
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kthread_stop(tsk_push);
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return PTR_ERR(tsk_pop);
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}
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start = ktime_get();
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wake_up_process(tsk_push);
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wake_up_process(tsk_pop);
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pr_info("waiting for test to complete\n");
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while (!wait_for_completion_timeout(&wait, msecs_to_jiffies(10000))) {
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/* exit if there is no progress for push or pop size */
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if (last_pushed == test_pushed || last_popped == test_popped) {
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WARN_ONCE(true, TEST_FAILED_PREFIX "no progress\n");
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force_exit = true;
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continue;
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}
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last_pushed = test_pushed;
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last_popped = test_popped;
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pr_info("page_frag_test progress: pushed = %d, popped = %d\n",
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test_pushed, test_popped);
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}
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if (force_exit) {
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pr_err(TEST_FAILED_PREFIX "exit with error\n");
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goto out;
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}
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duration = (u64)ktime_us_delta(ktime_get(), start);
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pr_info("%d of iterations for %s testing took: %lluus\n", nr_test,
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test_align ? "aligned" : "non-aligned", duration);
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out:
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ptr_ring_cleanup(&ptr_ring, NULL);
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page_frag_cache_drain(&test_nc);
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return -EAGAIN;
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}
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static void __exit page_frag_test_exit(void)
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{
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}
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module_init(page_frag_test_init);
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module_exit(page_frag_test_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Yunsheng Lin <[email protected]>");
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MODULE_DESCRIPTION("Test module for page_frag");

‎tools/testing/selftests/mm/run_vmtests.sh

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@@ -75,6 +75,8 @@ separated by spaces:
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read-only VMAs
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- mdwe
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test prctl(PR_SET_MDWE, ...)
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- page_frag
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test handling of page fragment allocation and freeing
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example: ./run_vmtests.sh -t "hmm mmap ksm"
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EOF
@@ -456,6 +458,12 @@ CATEGORY="mkdirty" run_test ./mkdirty
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CATEGORY="mdwe" run_test ./mdwe_test
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CATEGORY="page_frag" run_test ./test_page_frag.sh smoke
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CATEGORY="page_frag" run_test ./test_page_frag.sh aligned
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CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
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echo "SUMMARY: PASS=${count_pass} SKIP=${count_skip} FAIL=${count_fail}" | tap_prefix
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echo "1..${count_total}" | tap_output
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