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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 > --- > tools/testing/selftests/mm/hmm-tests.c | 29 ++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c > index e1c8a679a4cf3..d09d4a9081de1 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; > > @@ -2318,6 +2321,32 @@ 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); madvise(..., MADV_HUGEPAGE) is not sufficient to guarantee that the allocation was indeed converted to THP. Might be worth using the kpageflags interface (but that requires elevated privileges) and then KPF_THP? Otherwise the HMM_DMIRROR_PROT_PMD can be a miss from time to time. One other option is not to assert, but to check and inform? > + > + 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); > + If this is a THP entry, do we have valid pagemap entries for offset of i * page_size? > + ASSERT_NE(entry & PM_SWAP, 0); > + ASSERT_EQ(entry & PM_PRESENT, 0); Nit: You can use PAGEMAP_PRESENT() > + } > + > + 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); Balbir Singh