linux-stable/mm/gup_test.c
Pavel Tatashin e44605a8b1 selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages
When pages are pinned they can be faulted in userland and migrated, and
they can be faulted right in kernel without migration.

In either case, the pinned pages must end-up being pinnable (not
movable).

Add a new test to gup_test, to help verify that the gup/pup
(get_user_pages() / pin_user_pages()) behavior with respect to pinnable
and movable pages is reasonable and correct.  Specifically, provide a
way to:

1) Verify that only "pinnable" pages are pinned.  This is checked
   automatically for you.

2) Verify that gup/pup performance is reasonable.  This requires
   comparing benchmarks between doing gup/pup on pages that have been
   pre-faulted in from user space, vs.  doing gup/pup on pages that are
   not faulted in until gup/pup time (via FOLL_TOUCH).  This decision is
   controlled with the new -z command line option.

Link: https://lkml.kernel.org/r/20210215161349.246722-15-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:26 -07:00

250 lines
5.6 KiB
C

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/ktime.h>
#include <linux/debugfs.h>
#include "gup_test.h"
static void put_back_pages(unsigned int cmd, struct page **pages,
unsigned long nr_pages, unsigned int gup_test_flags)
{
unsigned long i;
switch (cmd) {
case GUP_FAST_BENCHMARK:
case GUP_BASIC_TEST:
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
break;
case PIN_FAST_BENCHMARK:
case PIN_BASIC_TEST:
case PIN_LONGTERM_BENCHMARK:
unpin_user_pages(pages, nr_pages);
break;
case DUMP_USER_PAGES_TEST:
if (gup_test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN) {
unpin_user_pages(pages, nr_pages);
} else {
for (i = 0; i < nr_pages; i++)
put_page(pages[i]);
}
break;
}
}
static void verify_dma_pinned(unsigned int cmd, struct page **pages,
unsigned long nr_pages)
{
unsigned long i;
struct page *page;
switch (cmd) {
case PIN_FAST_BENCHMARK:
case PIN_BASIC_TEST:
case PIN_LONGTERM_BENCHMARK:
for (i = 0; i < nr_pages; i++) {
page = pages[i];
if (WARN(!page_maybe_dma_pinned(page),
"pages[%lu] is NOT dma-pinned\n", i)) {
dump_page(page, "gup_test failure");
break;
} else if (cmd == PIN_LONGTERM_BENCHMARK &&
WARN(!is_pinnable_page(page),
"pages[%lu] is NOT pinnable but pinned\n",
i)) {
dump_page(page, "gup_test failure");
break;
}
}
break;
}
}
static void dump_pages_test(struct gup_test *gup, struct page **pages,
unsigned long nr_pages)
{
unsigned int index_to_dump;
unsigned int i;
/*
* Zero out any user-supplied page index that is out of range. Remember:
* .which_pages[] contains a 1-based set of page indices.
*/
for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
if (gup->which_pages[i] > nr_pages) {
pr_warn("ZEROING due to out of range: .which_pages[%u]: %u\n",
i, gup->which_pages[i]);
gup->which_pages[i] = 0;
}
}
for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
index_to_dump = gup->which_pages[i];
if (index_to_dump) {
index_to_dump--; // Decode from 1-based, to 0-based
pr_info("---- page #%u, starting from user virt addr: 0x%llx\n",
index_to_dump, gup->addr);
dump_page(pages[index_to_dump],
"gup_test: dump_pages() test");
}
}
}
static int __gup_test_ioctl(unsigned int cmd,
struct gup_test *gup)
{
ktime_t start_time, end_time;
unsigned long i, nr_pages, addr, next;
long nr;
struct page **pages;
int ret = 0;
bool needs_mmap_lock =
cmd != GUP_FAST_BENCHMARK && cmd != PIN_FAST_BENCHMARK;
if (gup->size > ULONG_MAX)
return -EINVAL;
nr_pages = gup->size / PAGE_SIZE;
pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
if (!pages)
return -ENOMEM;
if (needs_mmap_lock && mmap_read_lock_killable(current->mm)) {
ret = -EINTR;
goto free_pages;
}
i = 0;
nr = gup->nr_pages_per_call;
start_time = ktime_get();
for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
if (nr != gup->nr_pages_per_call)
break;
next = addr + nr * PAGE_SIZE;
if (next > gup->addr + gup->size) {
next = gup->addr + gup->size;
nr = (next - addr) / PAGE_SIZE;
}
switch (cmd) {
case GUP_FAST_BENCHMARK:
nr = get_user_pages_fast(addr, nr, gup->gup_flags,
pages + i);
break;
case GUP_BASIC_TEST:
nr = get_user_pages(addr, nr, gup->gup_flags, pages + i,
NULL);
break;
case PIN_FAST_BENCHMARK:
nr = pin_user_pages_fast(addr, nr, gup->gup_flags,
pages + i);
break;
case PIN_BASIC_TEST:
nr = pin_user_pages(addr, nr, gup->gup_flags, pages + i,
NULL);
break;
case PIN_LONGTERM_BENCHMARK:
nr = pin_user_pages(addr, nr,
gup->gup_flags | FOLL_LONGTERM,
pages + i, NULL);
break;
case DUMP_USER_PAGES_TEST:
if (gup->test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
nr = pin_user_pages(addr, nr, gup->gup_flags,
pages + i, NULL);
else
nr = get_user_pages(addr, nr, gup->gup_flags,
pages + i, NULL);
break;
default:
ret = -EINVAL;
goto unlock;
}
if (nr <= 0)
break;
i += nr;
}
end_time = ktime_get();
/* Shifting the meaning of nr_pages: now it is actual number pinned: */
nr_pages = i;
gup->get_delta_usec = ktime_us_delta(end_time, start_time);
gup->size = addr - gup->addr;
/*
* Take an un-benchmark-timed moment to verify DMA pinned
* state: print a warning if any non-dma-pinned pages are found:
*/
verify_dma_pinned(cmd, pages, nr_pages);
if (cmd == DUMP_USER_PAGES_TEST)
dump_pages_test(gup, pages, nr_pages);
start_time = ktime_get();
put_back_pages(cmd, pages, nr_pages, gup->test_flags);
end_time = ktime_get();
gup->put_delta_usec = ktime_us_delta(end_time, start_time);
unlock:
if (needs_mmap_lock)
mmap_read_unlock(current->mm);
free_pages:
kvfree(pages);
return ret;
}
static long gup_test_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg)
{
struct gup_test gup;
int ret;
switch (cmd) {
case GUP_FAST_BENCHMARK:
case PIN_FAST_BENCHMARK:
case PIN_LONGTERM_BENCHMARK:
case GUP_BASIC_TEST:
case PIN_BASIC_TEST:
case DUMP_USER_PAGES_TEST:
break;
default:
return -EINVAL;
}
if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
return -EFAULT;
ret = __gup_test_ioctl(cmd, &gup);
if (ret)
return ret;
if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
return -EFAULT;
return 0;
}
static const struct file_operations gup_test_fops = {
.open = nonseekable_open,
.unlocked_ioctl = gup_test_ioctl,
};
static int __init gup_test_init(void)
{
debugfs_create_file_unsafe("gup_test", 0600, NULL, NULL,
&gup_test_fops);
return 0;
}
late_initcall(gup_test_init);