On Thu, Jun 04, 2026 at 05:53:06AM +0000, Dev Jain wrote: > To cover pagemap paths scanning PMD entries, add assertions to check > whether a device-private PMD entry has the correct pagemap information - > the PM_SWAP bit must be on in the pagemap entry. Before that, we must > assert through HMM_DMIRROR_SNAPSHOT snapshot that the leaf entry is > at PMD level and not PTE level. > > Signed-off-by: Dev Jain <[email protected]>
LGTM, and confirmed this triggers the issue locally so: Reviewed-by: Lorenzo Stoakes <[email protected]> > --- > tools/testing/selftests/mm/hmm-tests.c | 34 ++++++++++++++++++++++++-- > 1 file changed, 32 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/mm/hmm-tests.c > b/tools/testing/selftests/mm/hmm-tests.c > index e1c8a679a4cf3..46e0c8c921c3d 100644 > --- a/tools/testing/selftests/mm/hmm-tests.c > +++ b/tools/testing/selftests/mm/hmm-tests.c > @@ -2276,8 +2276,11 @@ TEST_F(hmm, migrate_anon_huge_fault) > unsigned long npages; > unsigned long size; > unsigned long i; > + unsigned char *m; > + uint64_t entry; > void *old_ptr; > void *map; > + int pagemap_fd; > int *ptr; > int ret; > > @@ -2300,8 +2303,6 @@ TEST_F(hmm, migrate_anon_huge_fault) > > npages = size >> self->page_shift; > map = (void *)ALIGN((uintptr_t)buffer->ptr, size); > - ret = madvise(map, size, MADV_HUGEPAGE); > - ASSERT_EQ(ret, 0); > old_ptr = buffer->ptr; > buffer->ptr = map; > > @@ -2309,6 +2310,9 @@ TEST_F(hmm, migrate_anon_huge_fault) > for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) > ptr[i] = i; > > + ret = madvise(map, size, MADV_COLLAPSE); > + ASSERT_EQ(ret, 0); > + > /* Migrate memory to device. */ > ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages); > ASSERT_EQ(ret, 0); > @@ -2318,6 +2322,32 @@ TEST_F(hmm, migrate_anon_huge_fault) > for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) > ASSERT_EQ(ptr[i], i); > > + if (!hmm_is_coherent_type(variant->device_number)) { > + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, > + buffer, npages); > + ASSERT_EQ(ret, 0); > + ASSERT_EQ(buffer->cpages, npages); > + > + m = buffer->mirror; > + for (i = 0; i < npages; ++i) > + ASSERT_EQ(m[i], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL | > + HMM_DMIRROR_PROT_WRITE | > + HMM_DMIRROR_PROT_PMD); > + > + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); > + ASSERT_GE(pagemap_fd, 0); > + > + for (i = 0; i < npages; ++i) { > + entry = pagemap_get_entry(pagemap_fd, > + (char *)buffer->ptr + i * > self->page_size); > + > + ASSERT_NE(entry & PM_SWAP, 0); > + ASSERT_FALSE(PAGEMAP_PRESENT(entry)); > + } > + > + close(pagemap_fd); > + } > + > /* Fault pages back to system memory and check them. */ > for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) > ASSERT_EQ(ptr[i], i); > -- > 2.43.0 >
