| Message ID | 20210922102411.34494-5-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Free the 2nd vmemmap page associated with each HugeTLB page | expand |
On Wed, Sep 22, 2021 at 10:27 PM Muchun Song <songmuchun@bytedance.com> wrote: > > Since the head vmemmap page frame associated with each HugeTLB page is > reused, we should hide the PG_head flag of tail struct page from the > user. Add a tese case to check whether it is work properly. The test > steps are as follows. > > 1) alloc 2MB hugeTLB > 2) get each page frame > 3) apply those APIs in each page frame > 4) Those APIs work completely the same as before. > > Reading the flags of a page by /proc/kpageflags is done in > stable_page_flags(), which has invoked PageHead(), PageTail(), > PageCompound() and compound_head(). If those APIs work properly, the > head page must have 15 and 17 bits set. And tail pages must have 16 > and 17 bits set but 15 bit unset. Those flags are checked in > check_page_flags(). > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > tools/testing/selftests/vm/vmemmap_hugetlb.c | 144 +++++++++++++++++++++++++++ > 1 file changed, 144 insertions(+) > create mode 100644 tools/testing/selftests/vm/vmemmap_hugetlb.c > > diff --git a/tools/testing/selftests/vm/vmemmap_hugetlb.c b/tools/testing/selftests/vm/vmemmap_hugetlb.c > new file mode 100644 > index 000000000000..4cc74dd4c333 > --- /dev/null > +++ b/tools/testing/selftests/vm/vmemmap_hugetlb.c > @@ -0,0 +1,144 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * A test case of using hugepage memory in a user application using the > + * mmap system call with MAP_HUGETLB flag. Before running this program > + * make sure the administrator has allocated enough default sized huge > + * pages to cover the 2 MB allocation. > + * > + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. > + * That means the addresses starting with 0x800000... will need to be > + * specified. Specifying a fixed address is not required on ppc64, i386 > + * or x86_64. > + */ > +#include <stdlib.h> > +#include <stdio.h> > +#include <unistd.h> > +#include <sys/mman.h> > +#include <fcntl.h> > + > +#define MAP_LENGTH (2UL * 1024 * 1024) > + > +#ifndef MAP_HUGETLB > +#define MAP_HUGETLB 0x40000 /* arch specific */ > +#endif > + > +#define PAGE_SIZE 4096 > + > +#define PAGE_COMPOUND_HEAD (1UL << 15) > +#define PAGE_COMPOUND_TAIL (1UL << 16) > +#define PAGE_HUGE (1UL << 17) > + > +#define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE) > +#define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE) > + > +#define PM_PFRAME_BITS 55 > +#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1) > + better to move the comment here: + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. + * That means the addresses starting with 0x800000... will need to be + * specified. Specifying a fixed address is not required on ppc64, i386 + * or x86_64. With the change, Reviewed-by: Barry Song <song.bao.hua@hisilicon.com> > +/* Only ia64 requires this */ > +#ifdef __ia64__ > +#define MAP_ADDR (void *)(0x8000000000000000UL) > +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) > +#else > +#define MAP_ADDR NULL > +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) > +#endif > + > +static void write_bytes(char *addr, size_t length) > +{ > + unsigned long i; > + > + for (i = 0; i < length; i++) > + *(addr + i) = (char)i; > +} > + > +static unsigned long virt_to_pfn(void *addr) > +{ > + int fd; > + unsigned long pagemap; > + > + fd = open("/proc/self/pagemap", O_RDONLY); > + if (fd < 0) > + return -1UL; > + > + lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET); > + read(fd, &pagemap, sizeof(pagemap)); > + close(fd); > + > + return pagemap & ~PM_PFRAME_MASK; > +} > + > +static int check_page_flags(unsigned long pfn) > +{ > + int fd, i; > + unsigned long pageflags; > + > + fd = open("/proc/kpageflags", O_RDONLY); > + if (fd < 0) > + return -1; > + > + lseek(fd, pfn * sizeof(pageflags), SEEK_SET); > + > + read(fd, &pageflags, sizeof(pageflags)); > + if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) { > + close(fd); > + printf("Head page flags (%lx) is invalid\n", pageflags); > + return -1; > + } > + > + /* > + * pages other than the first page must be tail and shouldn't be head; > + * this also verifies kernel has correctly set the fake page_head to tail > + * while hugetlb_free_vmemmap is enabled. > + */ > + for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) { > + read(fd, &pageflags, sizeof(pageflags)); > + if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS || > + (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) { > + close(fd); > + printf("Tail page flags (%lx) is invalid\n", pageflags); > + return -1; > + } > + } > + > + close(fd); > + > + return 0; > +} > + > +int main(int argc, char **argv) > +{ > + void *addr; > + unsigned long pfn; > + > + addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); > + if (addr == MAP_FAILED) { > + perror("mmap"); > + exit(1); > + } > + > + /* Trigger allocation of HugeTLB page. */ > + write_bytes(addr, MAP_LENGTH); > + > + pfn = virt_to_pfn(addr); > + if (pfn == -1UL) { > + munmap(addr, MAP_LENGTH); > + perror("virt_to_pfn"); > + exit(1); > + } > + > + printf("Returned address is %p whose pfn is %lx\n", addr, pfn); > + > + if (check_page_flags(pfn) < 0) { > + munmap(addr, MAP_LENGTH); > + perror("check_page_flags"); > + exit(1); > + } > + > + /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ > + if (munmap(addr, MAP_LENGTH)) { > + perror("munmap"); > + exit(1); > + } > + > + return 0; > +} > -- > 2.11.0 > Thanks barry
On Fri, Sep 24, 2021 at 6:29 AM Barry Song <21cnbao@gmail.com> wrote: > > On Wed, Sep 22, 2021 at 10:27 PM Muchun Song <songmuchun@bytedance.com> wrote: > > > > Since the head vmemmap page frame associated with each HugeTLB page is > > reused, we should hide the PG_head flag of tail struct page from the > > user. Add a tese case to check whether it is work properly. The test > > steps are as follows. > > > > 1) alloc 2MB hugeTLB > > 2) get each page frame > > 3) apply those APIs in each page frame > > 4) Those APIs work completely the same as before. > > > > Reading the flags of a page by /proc/kpageflags is done in > > stable_page_flags(), which has invoked PageHead(), PageTail(), > > PageCompound() and compound_head(). If those APIs work properly, the > > head page must have 15 and 17 bits set. And tail pages must have 16 > > and 17 bits set but 15 bit unset. Those flags are checked in > > check_page_flags(). > > > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > > --- > > tools/testing/selftests/vm/vmemmap_hugetlb.c | 144 +++++++++++++++++++++++++++ > > 1 file changed, 144 insertions(+) > > create mode 100644 tools/testing/selftests/vm/vmemmap_hugetlb.c > > > > diff --git a/tools/testing/selftests/vm/vmemmap_hugetlb.c b/tools/testing/selftests/vm/vmemmap_hugetlb.c > > new file mode 100644 > > index 000000000000..4cc74dd4c333 > > --- /dev/null > > +++ b/tools/testing/selftests/vm/vmemmap_hugetlb.c > > @@ -0,0 +1,144 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * A test case of using hugepage memory in a user application using the > > + * mmap system call with MAP_HUGETLB flag. Before running this program > > + * make sure the administrator has allocated enough default sized huge > > + * pages to cover the 2 MB allocation. > > + * > > + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. > > + * That means the addresses starting with 0x800000... will need to be > > + * specified. Specifying a fixed address is not required on ppc64, i386 > > + * or x86_64. > > + */ > > +#include <stdlib.h> > > +#include <stdio.h> > > +#include <unistd.h> > > +#include <sys/mman.h> > > +#include <fcntl.h> > > + > > +#define MAP_LENGTH (2UL * 1024 * 1024) > > + > > +#ifndef MAP_HUGETLB > > +#define MAP_HUGETLB 0x40000 /* arch specific */ > > +#endif > > + > > +#define PAGE_SIZE 4096 > > + > > +#define PAGE_COMPOUND_HEAD (1UL << 15) > > +#define PAGE_COMPOUND_TAIL (1UL << 16) > > +#define PAGE_HUGE (1UL << 17) > > + > > +#define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE) > > +#define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE) > > + > > +#define PM_PFRAME_BITS 55 > > +#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1) > > + > > better to move the comment here: > > + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. > + * That means the addresses starting with 0x800000... will need to be > + * specified. Specifying a fixed address is not required on ppc64, i386 > + * or x86_64. > > With the change, > > Reviewed-by: Barry Song <song.bao.hua@hisilicon.com> Thanks. Will do. > > > +/* Only ia64 requires this */ > > +#ifdef __ia64__ > > +#define MAP_ADDR (void *)(0x8000000000000000UL) > > +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) > > +#else > > +#define MAP_ADDR NULL > > +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) > > +#endif > > + > > +static void write_bytes(char *addr, size_t length) > > +{ > > + unsigned long i; > > + > > + for (i = 0; i < length; i++) > > + *(addr + i) = (char)i; > > +} > > + > > +static unsigned long virt_to_pfn(void *addr) > > +{ > > + int fd; > > + unsigned long pagemap; > > + > > + fd = open("/proc/self/pagemap", O_RDONLY); > > + if (fd < 0) > > + return -1UL; > > + > > + lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET); > > + read(fd, &pagemap, sizeof(pagemap)); > > + close(fd); > > + > > + return pagemap & ~PM_PFRAME_MASK; > > +} > > + > > +static int check_page_flags(unsigned long pfn) > > +{ > > + int fd, i; > > + unsigned long pageflags; > > + > > + fd = open("/proc/kpageflags", O_RDONLY); > > + if (fd < 0) > > + return -1; > > + > > + lseek(fd, pfn * sizeof(pageflags), SEEK_SET); > > + > > + read(fd, &pageflags, sizeof(pageflags)); > > + if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) { > > + close(fd); > > + printf("Head page flags (%lx) is invalid\n", pageflags); > > + return -1; > > + } > > + > > + /* > > + * pages other than the first page must be tail and shouldn't be head; > > + * this also verifies kernel has correctly set the fake page_head to tail > > + * while hugetlb_free_vmemmap is enabled. > > + */ > > + for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) { > > + read(fd, &pageflags, sizeof(pageflags)); > > + if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS || > > + (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) { > > + close(fd); > > + printf("Tail page flags (%lx) is invalid\n", pageflags); > > + return -1; > > + } > > + } > > + > > + close(fd); > > + > > + return 0; > > +} > > + > > +int main(int argc, char **argv) > > +{ > > + void *addr; > > + unsigned long pfn; > > + > > + addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); > > + if (addr == MAP_FAILED) { > > + perror("mmap"); > > + exit(1); > > + } > > + > > + /* Trigger allocation of HugeTLB page. */ > > + write_bytes(addr, MAP_LENGTH); > > + > > + pfn = virt_to_pfn(addr); > > + if (pfn == -1UL) { > > + munmap(addr, MAP_LENGTH); > > + perror("virt_to_pfn"); > > + exit(1); > > + } > > + > > + printf("Returned address is %p whose pfn is %lx\n", addr, pfn); > > + > > + if (check_page_flags(pfn) < 0) { > > + munmap(addr, MAP_LENGTH); > > + perror("check_page_flags"); > > + exit(1); > > + } > > + > > + /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ > > + if (munmap(addr, MAP_LENGTH)) { > > + perror("munmap"); > > + exit(1); > > + } > > + > > + return 0; > > +} > > -- > > 2.11.0 > > > > Thanks > barry
diff --git a/tools/testing/selftests/vm/vmemmap_hugetlb.c b/tools/testing/selftests/vm/vmemmap_hugetlb.c new file mode 100644 index 000000000000..4cc74dd4c333 --- /dev/null +++ b/tools/testing/selftests/vm/vmemmap_hugetlb.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A test case of using hugepage memory in a user application using the + * mmap system call with MAP_HUGETLB flag. Before running this program + * make sure the administrator has allocated enough default sized huge + * pages to cover the 2 MB allocation. + * + * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. + * That means the addresses starting with 0x800000... will need to be + * specified. Specifying a fixed address is not required on ppc64, i386 + * or x86_64. + */ +#include <stdlib.h> +#include <stdio.h> +#include <unistd.h> +#include <sys/mman.h> +#include <fcntl.h> + +#define MAP_LENGTH (2UL * 1024 * 1024) + +#ifndef MAP_HUGETLB +#define MAP_HUGETLB 0x40000 /* arch specific */ +#endif + +#define PAGE_SIZE 4096 + +#define PAGE_COMPOUND_HEAD (1UL << 15) +#define PAGE_COMPOUND_TAIL (1UL << 16) +#define PAGE_HUGE (1UL << 17) + +#define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE) +#define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE) + +#define PM_PFRAME_BITS 55 +#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1) + +/* Only ia64 requires this */ +#ifdef __ia64__ +#define MAP_ADDR (void *)(0x8000000000000000UL) +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) +#else +#define MAP_ADDR NULL +#define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) +#endif + +static void write_bytes(char *addr, size_t length) +{ + unsigned long i; + + for (i = 0; i < length; i++) + *(addr + i) = (char)i; +} + +static unsigned long virt_to_pfn(void *addr) +{ + int fd; + unsigned long pagemap; + + fd = open("/proc/self/pagemap", O_RDONLY); + if (fd < 0) + return -1UL; + + lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET); + read(fd, &pagemap, sizeof(pagemap)); + close(fd); + + return pagemap & ~PM_PFRAME_MASK; +} + +static int check_page_flags(unsigned long pfn) +{ + int fd, i; + unsigned long pageflags; + + fd = open("/proc/kpageflags", O_RDONLY); + if (fd < 0) + return -1; + + lseek(fd, pfn * sizeof(pageflags), SEEK_SET); + + read(fd, &pageflags, sizeof(pageflags)); + if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) { + close(fd); + printf("Head page flags (%lx) is invalid\n", pageflags); + return -1; + } + + /* + * pages other than the first page must be tail and shouldn't be head; + * this also verifies kernel has correctly set the fake page_head to tail + * while hugetlb_free_vmemmap is enabled. + */ + for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) { + read(fd, &pageflags, sizeof(pageflags)); + if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS || + (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) { + close(fd); + printf("Tail page flags (%lx) is invalid\n", pageflags); + return -1; + } + } + + close(fd); + + return 0; +} + +int main(int argc, char **argv) +{ + void *addr; + unsigned long pfn; + + addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); + if (addr == MAP_FAILED) { + perror("mmap"); + exit(1); + } + + /* Trigger allocation of HugeTLB page. */ + write_bytes(addr, MAP_LENGTH); + + pfn = virt_to_pfn(addr); + if (pfn == -1UL) { + munmap(addr, MAP_LENGTH); + perror("virt_to_pfn"); + exit(1); + } + + printf("Returned address is %p whose pfn is %lx\n", addr, pfn); + + if (check_page_flags(pfn) < 0) { + munmap(addr, MAP_LENGTH); + perror("check_page_flags"); + exit(1); + } + + /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ + if (munmap(addr, MAP_LENGTH)) { + perror("munmap"); + exit(1); + } + + return 0; +}
Since the head vmemmap page frame associated with each HugeTLB page is reused, we should hide the PG_head flag of tail struct page from the user. Add a tese case to check whether it is work properly. The test steps are as follows. 1) alloc 2MB hugeTLB 2) get each page frame 3) apply those APIs in each page frame 4) Those APIs work completely the same as before. Reading the flags of a page by /proc/kpageflags is done in stable_page_flags(), which has invoked PageHead(), PageTail(), PageCompound() and compound_head(). If those APIs work properly, the head page must have 15 and 17 bits set. And tail pages must have 16 and 17 bits set but 15 bit unset. Those flags are checked in check_page_flags(). Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- tools/testing/selftests/vm/vmemmap_hugetlb.c | 144 +++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 tools/testing/selftests/vm/vmemmap_hugetlb.c