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Shutemov" , Roman Gushchin , Andrew Morton , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Yang Shi , Michal Hocko , John Hubbard , Ralph Campbell , David Nellans , Zi Yan Subject: [RFC PATCH 1/6] mm: huge_memory: add new debugfs interface to trigger split huge page on any page range. Date: Wed, 11 Nov 2020 15:40:03 -0500 Message-Id: <20201111204008.21332-2-zi.yan@sent.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201111204008.21332-1-zi.yan@sent.com> References: <20201111204008.21332-1-zi.yan@sent.com> Reply-To: Zi Yan MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Zi Yan Huge pages in the process with the given pid and virtual address range are split. It is used to test split huge page function. In addition, a testing program is added to tools/testing/selftests/vm to utilize the interface by splitting PMD THPs. Signed-off-by: Zi Yan --- mm/huge_memory.c | 98 +++++++++++ mm/internal.h | 1 + mm/migrate.c | 2 +- tools/testing/selftests/vm/Makefile | 1 + .../selftests/vm/split_huge_page_test.c | 161 ++++++++++++++++++ 5 files changed, 262 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/vm/split_huge_page_test.c diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 207ebca8c654..c4fead5ead31 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -7,6 +7,7 @@ =20 #include #include +#include #include #include #include @@ -2935,10 +2936,107 @@ static int split_huge_pages_set(void *data, u64 va= l) DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, "%llu\n"); =20 +static ssize_t split_huge_pages_in_range_pid_write(struct file *file, + const char __user *buf, size_t count, loff_t *ppops) +{ + static DEFINE_MUTEX(mutex); + ssize_t ret; + char input_buf[80]; /* hold pid, start_vaddr, end_vaddr */ + int pid; + unsigned long vaddr_start, vaddr_end, addr; + nodemask_t task_nodes; + struct mm_struct *mm; + + ret =3D mutex_lock_interruptible(&mutex); + if (ret) + return ret; + + ret =3D -EFAULT; + + memset(input_buf, 0, 80); + if (copy_from_user(input_buf, buf, min_t(size_t, count, 80))) + goto out; + + input_buf[80] =3D '\0'; + ret =3D sscanf(input_buf, "%d,%lx,%lx", &pid, &vaddr_start, &vaddr_end); + if (ret !=3D 3) { + ret =3D -EINVAL; + goto out; + } + vaddr_start &=3D PAGE_MASK; + vaddr_end &=3D PAGE_MASK; + + ret =3D strlen(input_buf); + pr_debug("split huge pages in pid: %d, vaddr: [%lx - %lx]\n", + pid, vaddr_start, vaddr_end); + + mm =3D find_mm_struct(pid, &task_nodes); + if (IS_ERR(mm)) { + ret =3D -EINVAL; + goto out; + } + + mmap_read_lock(mm); + for (addr =3D vaddr_start; addr < vaddr_end;) { + struct vm_area_struct *vma =3D find_vma(mm, addr); + unsigned int follflags; + struct page *page; + + if (!vma || addr < vma->vm_start || !vma_migratable(vma)) + break; + + /* FOLL_DUMP to ignore special (like zero) pages */ + follflags =3D FOLL_GET | FOLL_DUMP; + page =3D follow_page(vma, addr, follflags); + + if (IS_ERR(page)) + break; + if (!page) + break; + + if (!is_transparent_hugepage(page)) + goto next; + + if (!can_split_huge_page(page, NULL)) + goto next; + + if (!trylock_page(page)) + goto next; + + addr +=3D page_size(page) - PAGE_SIZE; + + /* reset addr if split fails */ + if (split_huge_page(page)) + addr -=3D (page_size(page) - PAGE_SIZE); + + unlock_page(page); +next: + /* next page */ + addr +=3D page_size(page); + put_page(page); + } + mmap_read_unlock(mm); + + + mmput(mm); +out: + mutex_unlock(&mutex); + return ret; + +} + +static const struct file_operations split_huge_pages_in_range_pid_fops =3D= { + .owner =3D THIS_MODULE, + .write =3D split_huge_pages_in_range_pid_write, + .llseek =3D no_llseek, +}; + static int __init split_huge_pages_debugfs(void) { debugfs_create_file("split_huge_pages", 0200, NULL, NULL, &split_huge_pages_fops); + debugfs_create_file("split_huge_pages_in_range_pid", 0200, NULL, NULL, + &split_huge_pages_in_range_pid_fops); return 0; } late_initcall(split_huge_pages_debugfs); diff --git a/mm/internal.h b/mm/internal.h index 3ea43642b99d..fd841a38830f 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -624,4 +624,5 @@ struct migration_target_control { =20 bool truncate_inode_partial_page(struct page *page, loff_t start, loff_t e= nd); void page_cache_free_page(struct address_space *mapping, struct page *page= ); +struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes); #endif /* __MM_INTERNAL_H */ diff --git a/mm/migrate.c b/mm/migrate.c index a50bbb0e029b..e35654d1087d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1851,7 +1851,7 @@ static int do_pages_stat(struct mm_struct *mm, unsign= ed long nr_pages, return nr_pages ? -EFAULT : 0; } =20 -static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) +struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) { struct task_struct *task; struct mm_struct *mm; diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/= vm/Makefile index 62fb15f286ee..d9ead0cdd3e9 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -42,6 +42,7 @@ TEST_GEN_FILES +=3D on-fault-limit TEST_GEN_FILES +=3D thuge-gen TEST_GEN_FILES +=3D transhuge-stress TEST_GEN_FILES +=3D userfaultfd +TEST_GEN_FILES +=3D split_huge_page_test =20 ifeq ($(ARCH),x86_64) CAN_BUILD_I386 :=3D $(shell ./../x86/check_cc.sh $(CC) ../x86/trivial_32bi= t_program.c -m32) diff --git a/tools/testing/selftests/vm/split_huge_page_test.c b/tools/test= ing/selftests/vm/split_huge_page_test.c new file mode 100644 index 000000000000..c8a32ae9e13a --- /dev/null +++ b/tools/testing/selftests/vm/split_huge_page_test.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include "numa.h" +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define PAGE_4KB (4096UL) +#define PAGE_2MB (512UL*PAGE_4KB) +#define PAGE_1GB (512UL*PAGE_2MB) + +#define PRESENT_MASK (1UL<<63) +#define SWAPPED_MASK (1UL<<62) +#define PAGE_TYPE_MASK (1UL<<61) +#define PFN_MASK ((1UL<<55)-1) + +#define KPF_THP (1UL<<22) +#define KPF_PUD_THP (1UL<<27) + +#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages_in_range_pid" +#define SMAP_PATH "/proc/self/smaps" +#define INPUT_MAX 80 + +static int write_file(const char *path, const char *buf, size_t buflen) +{ + int fd; + ssize_t numwritten; + + fd =3D open(path, O_WRONLY); + if (fd =3D=3D -1) + return 0; + + numwritten =3D write(fd, buf, buflen - 1); + close(fd); + if (numwritten < 1) + return 0; + + return (unsigned int) numwritten; +} + +static void write_debugfs(int pid, uint64_t vaddr_start, uint64_t vaddr_en= d) +{ + char input[INPUT_MAX]; + int ret; + + ret =3D snprintf(input, INPUT_MAX, "%d,%lx,%lx", pid, vaddr_start, + vaddr_end); + if (ret >=3D INPUT_MAX) { + printf("%s: Debugfs input is too long\n", __func__); + exit(EXIT_FAILURE); + } + + if (!write_file(SPLIT_DEBUGFS, input, ret + 1)) { + perror(SPLIT_DEBUGFS); + exit(EXIT_FAILURE); + } +} + +#define MAX_LINE_LENGTH 500 + +static bool check_for_pattern(FILE *fp, char *pattern, char *buf) +{ + while (fgets(buf, MAX_LINE_LENGTH, fp) !=3D NULL) { + if (!strncmp(buf, pattern, strlen(pattern))) + return true; + } + return false; +} + +static uint64_t check_huge(void *addr) +{ + uint64_t thp =3D 0; + int ret; + FILE *fp; + char buffer[MAX_LINE_LENGTH]; + char addr_pattern[MAX_LINE_LENGTH]; + + ret =3D snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-", + (unsigned long) addr); + if (ret >=3D MAX_LINE_LENGTH) { + printf("%s: Pattern is too long\n", __func__); + exit(EXIT_FAILURE); + } + + + fp =3D fopen(SMAP_PATH, "r"); + if (!fp) { + printf("%s: Failed to open file %s\n", __func__, SMAP_PATH); + exit(EXIT_FAILURE); + } + if (!check_for_pattern(fp, addr_pattern, buffer)) + goto err_out; + + /* + * Fetch the AnonHugePages: in the same block and check the number of + * hugepages. + */ + if (!check_for_pattern(fp, "AnonHugePages:", buffer)) + goto err_out; + + if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) !=3D 1) { + printf("Reading smap error\n"); + exit(EXIT_FAILURE); + } + +err_out: + fclose(fp); + return thp; +} + +void split_pmd_thp(void) +{ + char *one_page; + size_t len =3D 4 * PAGE_2MB; + uint64_t thp_size; + + one_page =3D memalign(PAGE_1GB, len); + + madvise(one_page, len, MADV_HUGEPAGE); + + memset(one_page, 1, len); + + thp_size =3D check_huge(one_page); + if (!thp_size) { + printf("No THP is allocatd"); + exit(EXIT_FAILURE); + } + + /* split all possible huge pages */ + write_debugfs(getpid(), (uint64_t)one_page, (uint64_t)one_page + len); + + *one_page =3D 0; + + thp_size =3D check_huge(one_page); + if (thp_size) { + printf("Still %ld kB AnonHugePages not split\n", thp_size); + exit(EXIT_FAILURE); + } + + printf("Split huge pages successful\n"); + free(one_page); +} + +int main(int argc, char **argv) +{ + split_pmd_thp(); + + return 0; +} --=20 2.28.0