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userfaultfd: non-cooperative: selftest: add test for FORK, MADVDONTNE…
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…ED and REMAP events

Add test for userfaultfd events used in non-cooperative scenario when
the process that monitors the userfaultfd and handles user faults is not
the same process that causes the page faults.

Link: http://lkml.kernel.org/r/20161216144821.5183-41-aarcange@redhat.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mike Rapoport authored and Linus Torvalds committed Feb 23, 2017
1 parent aa0d272 commit da5502c
Showing 1 changed file with 163 additions and 12 deletions.
175 changes: 163 additions & 12 deletions tools/testing/selftests/vm/userfaultfd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <pthread.h>
#include <linux/userfaultfd.h>

Expand Down Expand Up @@ -347,6 +348,7 @@ static void *uffd_poll_thread(void *arg)
unsigned long cpu = (unsigned long) arg;
struct pollfd pollfd[2];
struct uffd_msg msg;
struct uffdio_register uffd_reg;
int ret;
unsigned long offset;
char tmp_chr;
Expand Down Expand Up @@ -378,16 +380,35 @@ static void *uffd_poll_thread(void *arg)
continue;
perror("nonblocking read error"), exit(1);
}
if (msg.event != UFFD_EVENT_PAGEFAULT)
switch (msg.event) {
default:
fprintf(stderr, "unexpected msg event %u\n",
msg.event), exit(1);
if (msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
fprintf(stderr, "unexpected write fault\n"), exit(1);
offset = (char *)(unsigned long)msg.arg.pagefault.address -
area_dst;
offset &= ~(page_size-1);
if (copy_page(uffd, offset))
userfaults++;
break;
case UFFD_EVENT_PAGEFAULT:
if (msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
fprintf(stderr, "unexpected write fault\n"), exit(1);
offset = (char *)(unsigned long)msg.arg.pagefault.address -
area_dst;
offset &= ~(page_size-1);
if (copy_page(uffd, offset))
userfaults++;
break;
case UFFD_EVENT_FORK:
uffd = msg.arg.fork.ufd;
pollfd[0].fd = uffd;
break;
case UFFD_EVENT_MADVDONTNEED:
uffd_reg.range.start = msg.arg.madv_dn.start;
uffd_reg.range.len = msg.arg.madv_dn.end -
msg.arg.madv_dn.start;
if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_reg.range))
fprintf(stderr, "madv_dn failure\n"), exit(1);
break;
case UFFD_EVENT_REMAP:
area_dst = (char *)(unsigned long)msg.arg.remap.to;
break;
}
}
return (void *)userfaults;
}
Expand Down Expand Up @@ -512,7 +533,7 @@ static int stress(unsigned long *userfaults)
return 0;
}

static int userfaultfd_open(void)
static int userfaultfd_open(int features)
{
struct uffdio_api uffdio_api;

Expand All @@ -525,7 +546,7 @@ static int userfaultfd_open(void)
uffd_flags = fcntl(uffd, F_GETFD, NULL);

uffdio_api.api = UFFD_API;
uffdio_api.features = 0;
uffdio_api.features = features;
if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
fprintf(stderr, "UFFDIO_API\n");
return 1;
Expand All @@ -538,6 +559,132 @@ static int userfaultfd_open(void)
return 0;
}

/*
* For non-cooperative userfaultfd test we fork() a process that will
* generate pagefaults, will mremap the area monitored by the
* userfaultfd and at last this process will release the monitored
* area.
* For the anonymous and shared memory the area is divided into two
* parts, the first part is accessed before mremap, and the second
* part is accessed after mremap. Since hugetlbfs does not support
* mremap, the entire monitored area is accessed in a single pass for
* HUGETLB_TEST.
* The release of the pages currently generates event only for
* anonymous memory (UFFD_EVENT_MADVDONTNEED), hence it is not checked
* for hugetlb and shmem.
*/
static int faulting_process(void)
{
unsigned long nr;
unsigned long long count;

#ifndef HUGETLB_TEST
unsigned long split_nr_pages = (nr_pages + 1) / 2;
#else
unsigned long split_nr_pages = nr_pages;
#endif

for (nr = 0; nr < split_nr_pages; nr++) {
count = *area_count(area_dst, nr);
if (count != count_verify[nr]) {
fprintf(stderr,
"nr %lu memory corruption %Lu %Lu\n",
nr, count,
count_verify[nr]), exit(1);
}
}

#ifndef HUGETLB_TEST
area_dst = mremap(area_dst, nr_pages * page_size, nr_pages * page_size,
MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
if (area_dst == MAP_FAILED)
perror("mremap"), exit(1);

for (; nr < nr_pages; nr++) {
count = *area_count(area_dst, nr);
if (count != count_verify[nr]) {
fprintf(stderr,
"nr %lu memory corruption %Lu %Lu\n",
nr, count,
count_verify[nr]), exit(1);
}
}

#ifndef SHMEM_TEST
if (release_pages(area_dst))
return 1;

for (nr = 0; nr < nr_pages; nr++) {
if (my_bcmp(area_dst + nr * page_size, zeropage, page_size))
fprintf(stderr, "nr %lu is not zero\n", nr), exit(1);
}
#endif /* SHMEM_TEST */

#endif /* HUGETLB_TEST */

return 0;
}

static int userfaultfd_events_test(void)
{
struct uffdio_register uffdio_register;
unsigned long expected_ioctls;
unsigned long userfaults;
pthread_t uffd_mon;
int err, features;
pid_t pid;
char c;

printf("testing events (fork, remap, madv_dn): ");
fflush(stdout);

if (release_pages(area_dst))
return 1;

features = UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP |
UFFD_FEATURE_EVENT_MADVDONTNEED;
if (userfaultfd_open(features) < 0)
return 1;
fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);

uffdio_register.range.start = (unsigned long) area_dst;
uffdio_register.range.len = nr_pages * page_size;
uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
fprintf(stderr, "register failure\n"), exit(1);

expected_ioctls = EXPECTED_IOCTLS;
if ((uffdio_register.ioctls & expected_ioctls) !=
expected_ioctls)
fprintf(stderr,
"unexpected missing ioctl for anon memory\n"),
exit(1);

if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
perror("uffd_poll_thread create"), exit(1);

pid = fork();
if (pid < 0)
perror("fork"), exit(1);

if (!pid)
return faulting_process();

waitpid(pid, &err, 0);
if (err)
fprintf(stderr, "faulting process failed\n"), exit(1);

if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
perror("pipe write"), exit(1);
if (pthread_join(uffd_mon, (void **)&userfaults))
return 1;

close(uffd);
printf("userfaults: %ld\n", userfaults);

return userfaults != nr_pages;
}

static int userfaultfd_stress(void)
{
void *area;
Expand All @@ -555,7 +702,7 @@ static int userfaultfd_stress(void)
if (!area_dst)
return 1;

if (userfaultfd_open() < 0)
if (userfaultfd_open(0) < 0)
return 1;

count_verify = malloc(nr_pages * sizeof(unsigned long long));
Expand Down Expand Up @@ -702,7 +849,11 @@ static int userfaultfd_stress(void)
printf("\n");
}

return err;
if (err)
return err;

close(uffd);
return userfaultfd_events_test();
}

#ifndef HUGETLB_TEST
Expand Down

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