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[85.23.51.1]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59e0a43e8ebsm3221336e87.55.2026.02.02.03.26.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Feb 2026 03:26:47 -0800 (PST) From: mpenttil@redhat.com To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?Mika=20Penttil=C3=A4?= , David Hildenbrand , Jason Gunthorpe , Leon Romanovsky , Alistair Popple , Balbir Singh , Zi Yan , Matthew Brost , Marco Pagani Subject: [PATCH v4 2/3] mm: add new testcase for the migrate on fault case Date: Mon, 2 Feb 2026 13:26:21 +0200 Message-ID: <20260202112622.2104213-3-mpenttil@redhat.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20260202112622.2104213-1-mpenttil@redhat.com> References: <20260202112622.2104213-1-mpenttil@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Mika Penttil=C3=A4 Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Alistair Popple Cc: Balbir Singh Cc: Zi Yan Cc: Matthew Brost Signed-off-by: Marco Pagani Signed-off-by: Mika Penttil=C3=A4 --- lib/test_hmm.c | 100 ++++++++++++++++++++++++- lib/test_hmm_uapi.h | 19 ++--- tools/testing/selftests/mm/hmm-tests.c | 54 +++++++++++++ 3 files changed, 163 insertions(+), 10 deletions(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 455a6862ae50..8e8c8970d1f7 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -36,6 +36,7 @@ #define DMIRROR_RANGE_FAULT_TIMEOUT 1000 #define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U) #define DEVMEM_CHUNKS_RESERVE 16 +#define PFNS_ARRAY_SIZE 64 =20 /* * For device_private pages, dpage is just a dummy struct page @@ -145,7 +146,7 @@ static bool dmirror_is_private_zone(struct dmirror_devi= ce *mdevice) HMM_DMIRROR_MEMORY_DEVICE_PRIVATE); } =20 -static enum migrate_vma_direction +static enum migrate_vma_info dmirror_select_device(struct dmirror *dmirror) { return (dmirror->mdevice->zone_device_type =3D=3D @@ -1196,6 +1197,99 @@ static int dmirror_migrate_to_device(struct dmirror = *dmirror, return ret; } =20 +static int do_fault_and_migrate(struct dmirror *dmirror, struct hmm_range = *range) +{ + struct migrate_vma *migrate =3D range->migrate; + int ret; + + mmap_read_lock(dmirror->notifier.mm); + + /* Fault-in pages for migration and update device page table */ + ret =3D dmirror_range_fault(dmirror, range); + + pr_debug("Migrating from sys mem to device mem\n"); + migrate_hmm_range_setup(range); + + dmirror_migrate_alloc_and_copy(migrate, dmirror); + migrate_vma_pages(migrate); + dmirror_migrate_finalize_and_map(migrate, dmirror); + migrate_vma_finalize(migrate); + + mmap_read_unlock(dmirror->notifier.mm); + return ret; +} + +static int dmirror_fault_and_migrate_to_device(struct dmirror *dmirror, + struct hmm_dmirror_cmd *cmd) +{ + unsigned long start, size, end, next; + unsigned long src_pfns[PFNS_ARRAY_SIZE] =3D { 0 }; + unsigned long dst_pfns[PFNS_ARRAY_SIZE] =3D { 0 }; + struct migrate_vma migrate =3D { 0 }; + struct hmm_range range =3D { 0 }; + struct dmirror_bounce bounce; + int ret =3D 0; + + /* Whole range */ + start =3D cmd->addr; + size =3D cmd->npages << PAGE_SHIFT; + end =3D start + size; + + if (!mmget_not_zero(dmirror->notifier.mm)) { + ret =3D -EFAULT; + goto out; + } + + migrate.pgmap_owner =3D dmirror->mdevice; + migrate.src =3D src_pfns; + migrate.dst =3D dst_pfns; + + range.migrate =3D &migrate; + range.hmm_pfns =3D src_pfns; + range.pfn_flags_mask =3D 0; + range.default_flags =3D HMM_PFN_REQ_FAULT | HMM_PFN_REQ_MIGRATE; + range.dev_private_owner =3D dmirror->mdevice; + range.notifier =3D &dmirror->notifier; + + for (next =3D start; next < end; next =3D range.end) { + range.start =3D next; + range.end =3D min(end, next + (PFNS_ARRAY_SIZE << PAGE_SHIFT)); + + pr_debug("Fault and migrate range start:%#lx end:%#lx\n", + range.start, range.end); + + ret =3D do_fault_and_migrate(dmirror, &range); + if (ret) + goto out_mmput; + } + + /* + * Return the migrated data for verification. + * Only for pages in device zone + */ + ret =3D dmirror_bounce_init(&bounce, start, size); + if (ret) + goto out_mmput; + + mutex_lock(&dmirror->mutex); + ret =3D dmirror_do_read(dmirror, start, end, &bounce); + mutex_unlock(&dmirror->mutex); + if (ret =3D=3D 0) { + ret =3D copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr, bounce.size); + if (ret) + ret =3D -EFAULT; + } + + cmd->cpages =3D bounce.cpages; + dmirror_bounce_fini(&bounce); + + +out_mmput: + mmput(dmirror->notifier.mm); +out: + return ret; +} + static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *ran= ge, unsigned char *perm, unsigned long entry) { @@ -1512,6 +1606,10 @@ static long dmirror_fops_unlocked_ioctl(struct file = *filp, ret =3D dmirror_migrate_to_device(dmirror, &cmd); break; =20 + case HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV: + ret =3D dmirror_fault_and_migrate_to_device(dmirror, &cmd); + break; + case HMM_DMIRROR_MIGRATE_TO_SYS: ret =3D dmirror_migrate_to_system(dmirror, &cmd); break; diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h index f94c6d457338..0b6e7a419e36 100644 --- a/lib/test_hmm_uapi.h +++ b/lib/test_hmm_uapi.h @@ -29,15 +29,16 @@ struct hmm_dmirror_cmd { }; =20 /* Expose the address space of the calling process through hmm device file= */ -#define HMM_DMIRROR_READ _IOWR('H', 0x00, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_WRITE _IOWR('H', 0x01, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_MIGRATE_TO_DEV _IOWR('H', 0x02, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_MIGRATE_TO_SYS _IOWR('H', 0x03, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_SNAPSHOT _IOWR('H', 0x04, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_CHECK_EXCLUSIVE _IOWR('H', 0x06, struct hmm_dmirror_cm= d) -#define HMM_DMIRROR_RELEASE _IOWR('H', 0x07, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_FLAGS _IOWR('H', 0x08, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_READ _IOWR('H', 0x00, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_WRITE _IOWR('H', 0x01, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_MIGRATE_TO_DEV _IOWR('H', 0x02, struct hmm_dmirror_cm= d) +#define HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV _IOWR('H', 0x03, struct hmm_dm= irror_cmd) +#define HMM_DMIRROR_MIGRATE_TO_SYS _IOWR('H', 0x04, struct hmm_dmirror_cm= d) +#define HMM_DMIRROR_SNAPSHOT _IOWR('H', 0x05, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x06, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_CHECK_EXCLUSIVE _IOWR('H', 0x07, struct hmm_dmirror_c= md) +#define HMM_DMIRROR_RELEASE _IOWR('H', 0x08, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_FLAGS _IOWR('H', 0x09, struct hmm_dmirror_cmd) =20 #define HMM_DMIRROR_FLAG_FAIL_ALLOC (1ULL << 0) =20 diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftes= ts/mm/hmm-tests.c index e8328c89d855..c75616875c9e 100644 --- a/tools/testing/selftests/mm/hmm-tests.c +++ b/tools/testing/selftests/mm/hmm-tests.c @@ -277,6 +277,13 @@ static int hmm_migrate_sys_to_dev(int fd, return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_DEV, buffer, npages); } =20 +static int hmm_migrate_on_fault_sys_to_dev(int fd, + struct hmm_buffer *buffer, + unsigned long npages) +{ + return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV, buffer, n= pages); +} + static int hmm_migrate_dev_to_sys(int fd, struct hmm_buffer *buffer, unsigned long npages) @@ -1034,6 +1041,53 @@ TEST_F(hmm, migrate) hmm_buffer_free(buffer); } =20 + +/* + * Fault and migrate anonymous memory to device private memory. + */ +TEST_F(hmm, migrate_on_fault) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + int *ptr; + int ret; + + npages =3D ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift; + ASSERT_NE(npages, 0); + size =3D npages << self->page_shift; + + buffer =3D malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd =3D -1; + buffer->size =3D size; + buffer->mirror =3D malloc(size); + ASSERT_NE(buffer->mirror, NULL); + + buffer->ptr =3D mmap(NULL, size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + /* Initialize buffer in system memory. */ + for (i =3D 0, ptr =3D buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] =3D i; + + /* Fault and migrate memory to device. */ + ret =3D hmm_migrate_on_fault_sys_to_dev(self->fd, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i =3D 0, ptr =3D buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + hmm_buffer_free(buffer); +} + /* * Migrate anonymous memory to device private memory and fault some of it = back * to system memory, then try migrating the resulting mix of system and de= vice --=20 2.50.0