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selftests/mm: extend and rename uffd pagemap test

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Extend it to all types of mem, meanwhile add one parallel test when
EVENT_FORK is enabled, where uffd-wp bits should be persisted rather than
dropped.

Since at it, rename the test to "wp-fork" to better show what it means. 
Making the new test called "wp-fork-with-event".

Before:

        Testing pagemap on anon... done

After:

        Testing wp-fork on anon... done
        Testing wp-fork on shmem... done
        Testing wp-fork on shmem-private... done
        Testing wp-fork on hugetlb... done
        Testing wp-fork on hugetlb-private... done
        Testing wp-fork-with-event on anon... done
        Testing wp-fork-with-event on shmem... done
        Testing wp-fork-with-event on shmem-private... done
        Testing wp-fork-with-event on hugetlb... done
        Testing wp-fork-with-event on hugetlb-private... done

Link: https://lkml.kernel.org/r/20230417195317.898696-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mika Penttilä <mpenttil@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Peter Xu 2023-04-17 15:53:15 -04:00 committed by Andrew Morton
parent 21337f2af1
commit cff2945827
1 changed files with 106 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

130
tools/testing/selftests/mm/uffd-unit-tests.c
View file

@ -227,25 +227,65 @@ static int pagemap_open(void)
err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \
} while (0)
static int pagemap_test_fork(bool present)
typedef struct {
int parent_uffd, child_uffd;
} fork_event_args;
static void *fork_event_consumer(void *data)
{
pid_t child = fork();
fork_event_args *args = data;
struct uffd_msg msg = { 0 };
/* Read until a full msg received */
while (uffd_read_msg(args->parent_uffd, &msg));
if (msg.event != UFFD_EVENT_FORK)
err("wrong message: %u\n", msg.event);
/* Just to be properly freed later */
args->child_uffd = msg.arg.fork.ufd;
return NULL;
}
static int pagemap_test_fork(int uffd, bool with_event)
{
fork_event_args args = { .parent_uffd = uffd, .child_uffd = -1 };
pthread_t thread;
pid_t child;
uint64_t value;
int fd, result;
/* Prepare a thread to resolve EVENT_FORK */
if (with_event) {
if (pthread_create(&thread, NULL, fork_event_consumer, &args))
err("pthread_create()");
}
child = fork();
if (!child) {
/* Open the pagemap fd of the child itself */
fd = pagemap_open();
value = pagemap_get_entry(fd, area_dst);
/*
* After fork() uffd-wp bit should be gone as long as we're
* without UFFD_FEATURE_EVENT_FORK
* After fork(), we should handle uffd-wp bit differently:
*
* (1) when with EVENT_FORK, it should persist
* (2) when without EVENT_FORK, it should be dropped
*/
pagemap_check_wp(value, false);
pagemap_check_wp(value, with_event);
/* Succeed */
exit(0);
}
waitpid(child, &result, 0);
if (with_event) {
if (pthread_join(thread, NULL))
err("pthread_join()");
if (args.child_uffd < 0)
err("Didn't receive child uffd");
close(args.child_uffd);
}
return result;
}
@ -295,7 +335,8 @@ static void uffd_wp_unpopulated_test(uffd_test_args_t *args)
uffd_test_pass();
}
static void uffd_pagemap_test(uffd_test_args_t *args)
static void uffd_wp_fork_test_common(uffd_test_args_t *args,
bool with_event)
{
int pagemap_fd;
uint64_t value;
@ -311,23 +352,42 @@ static void uffd_pagemap_test(uffd_test_args_t *args)
wp_range(uffd, (uint64_t)area_dst, page_size, true);
value = pagemap_get_entry(pagemap_fd, area_dst);
pagemap_check_wp(value, true);
/* Make sure uffd-wp bit dropped when fork */
if (pagemap_test_fork(true))
err("Detected stall uffd-wp bit in child");
if (pagemap_test_fork(uffd, with_event)) {
uffd_test_fail("Detected %s uffd-wp bit in child in present pte",
with_event ? "missing" : "stall");
goto out;
}
/* Exclusive required or PAGEOUT won't work */
if (!(value & PM_MMAP_EXCLUSIVE))
err("multiple mapping detected: 0x%"PRIx64, value);
if (madvise(area_dst, page_size, MADV_PAGEOUT))
err("madvise(MADV_PAGEOUT) failed");
/*
* This is an attempt for zapping the pgtable so as to test the
* markers.
*
* For private mappings, PAGEOUT will only work on exclusive ptes
* (PM_MMAP_EXCLUSIVE) which we should satisfy.
*
* For shared, PAGEOUT may not work. Use DONTNEED instead which
* plays a similar role of zapping (rather than freeing the page)
* to expose pte markers.
*/
if (args->mem_type->shared) {
if (madvise(area_dst, page_size, MADV_DONTNEED))
err("MADV_DONTNEED");
} else {
/*
* NOTE: ignore retval because private-hugetlb doesn't yet
* support swapping, so it could fail.
*/
madvise(area_dst, page_size, MADV_PAGEOUT);
}
/* Uffd-wp should persist even swapped out */
value = pagemap_get_entry(pagemap_fd, area_dst);
pagemap_check_wp(value, true);
/* Make sure uffd-wp bit dropped when fork */
if (pagemap_test_fork(false))
err("Detected stall uffd-wp bit in child");
if (pagemap_test_fork(uffd, with_event)) {
uffd_test_fail("Detected %s uffd-wp bit in child in zapped pte",
with_event ? "missing" : "stall");
goto out;
}
/* Unprotect; this tests swap pte modifications */
wp_range(uffd, (uint64_t)area_dst, page_size, false);
@ -338,9 +398,21 @@ static void uffd_pagemap_test(uffd_test_args_t *args)
*area_dst = 2;
value = pagemap_get_entry(pagemap_fd, area_dst);
pagemap_check_wp(value, false);
close(pagemap_fd);
uffd_test_pass();
out:
if (uffd_unregister(uffd, area_dst, nr_pages * page_size))
err("unregister failed");
close(pagemap_fd);
}
static void uffd_wp_fork_test(uffd_test_args_t *args)
{
uffd_wp_fork_test_common(args, false);
}
static void uffd_wp_fork_with_event_test(uffd_test_args_t *args)
{
uffd_wp_fork_test_common(args, true);
}
static void check_memory_contents(char *p)
@ -836,10 +908,20 @@ uffd_test_case_t uffd_tests[] = {
.uffd_feature_required = 0,
},
{
.name = "pagemap",
.uffd_fn = uffd_pagemap_test,
.mem_targets = MEM_ANON,
.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP,
.name = "wp-fork",
.uffd_fn = uffd_wp_fork_test,
.mem_targets = MEM_ALL,
.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
},
{
.name = "wp-fork-with-event",
.uffd_fn = uffd_wp_fork_with_event_test,
.mem_targets = MEM_ALL,
.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
/* when set, child process should inherit uffd-wp bits */
UFFD_FEATURE_EVENT_FORK,
},
{
.name = "wp-unpopulated",