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