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selftests/mm/hmm-tests: test pagemap reads of PMD device-private entries

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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.

Link: https://lore.kernel.org/20260604055308.1947679-3-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Oscar Salvador (SUSE) <osalvador@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dev Jain
2026-06-04 05:53:06 +00:00
committed by Andrew Morton
parent cd1fc0e3c1
commit e3d8707358
1 changed files with 32 additions and 2 deletions
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34
tools/testing/selftests/mm/hmm-tests.c
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@@ -2274,8 +2274,11 @@ 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;
@@ -2298,8 +2301,6 @@ 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;
@@ -2307,6 +2308,9 @@ 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);
@@ -2316,6 +2320,32 @@ 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);