* + tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch added to mm-unstable branch
@ 2026-08-06 23:29 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-08-06 23:29 UTC (permalink / raw)
To: mm-commits, ljs, akpm
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 9522 bytes --]
The patch titled
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
has been added to the -mm mm-unstable branch. Its filename is
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
Date: Thu, 06 Aug 2026 21:21:44 +0100
Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add
a VMA userland test to assert that this is the case and everything is as
we would expect for an anonymous mapping.
Link: https://lore.kernel.org/20260806-b4-scalable-cow-virt-pgoff-v4-19-ab318a350404@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price (Meta) <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang Ray <Ray.Huang@amd.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: <syzbot@syzkaller.appspotmail.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Xu Xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/vma/include/dup.h | 1
tools/testing/vma/tests/mmap.c | 50 ++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
--- a/tools/testing/vma/include/dup.h~tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon
+++ a/tools/testing/vma/include/dup.h
@@ -20,6 +20,7 @@ struct task_struct *get_current(void);
#define MAJOR(dev) ((unsigned int) ((dev) >> MINORBITS))
#define MINOR(dev) ((unsigned int) ((dev) & MINORMASK))
+#define MKDEV(ma, mi) (((ma) << MINORBITS) | (mi))
#define S_IFMT 00170000
#define S_IFCHR 0020000
--- a/tools/testing/vma/tests/mmap.c~tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon
+++ a/tools/testing/vma/tests/mmap.c
@@ -45,7 +45,57 @@ static bool test_mmap_region_basic(void)
return true;
}
+static int dummy_mmap_prepare(struct vm_area_desc *desc)
+{
+ return 0;
+}
+
+static bool test_pure_anon_dev_zero(void)
+{
+ const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
+ VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
+ const struct file_operations f_op = {
+ .mmap_prepare = dummy_mmap_prepare,
+ };
+ struct inode inode = {
+ .i_mode = S_IFCHR,
+ .i_rdev = MKDEV(MEM_MAJOR, DEVZERO_MINOR),
+ };
+ struct file file = {
+ .f_inode = &inode,
+ .f_op = &f_op,
+ };
+ struct mm_struct mm = {};
+ struct vm_area_struct *vma;
+ unsigned long addr;
+ VMA_ITERATOR(vmi, &mm, 0);
+
+ current->mm = &mm;
+
+ /*
+ * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page
+ * offset of 0x10, which we expect to be reset to the anonymous page
+ * offset.
+ */
+ addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL);
+ ASSERT_EQ(addr, 0x300000);
+
+ /* Assert that it truly is an anonymous mapping. */
+ vma = vma_lookup(&mm, addr);
+ ASSERT_NE(vma, NULL);
+ ASSERT_TRUE(vma_is_anonymous(vma));
+ ASSERT_EQ(vma->vm_file, NULL);
+ ASSERT_EQ(vma->vm_private_data, NULL);
+ /* Expect anonymous page offsets. */
+ ASSERT_EQ(vma->vm_pgoff, 0x300);
+ ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300);
+
+ cleanup_mm(&mm, &vmi);
+ return true;
+}
+
static void run_mmap_tests(int *num_tests, int *num_fail)
{
TEST(mmap_region_basic);
+ TEST(pure_anon_dev_zero);
}
_
Patches currently in -mm which might be from ljs@kernel.org are
x86-mm-pat-acquire-init_mm-write-lock-on-collapse-to-avoid-uaf.patch
x86-mm-pat-acquire-init_mm-read-lock-on-attribute-change-to-avoid-uaf.patch
x86-mm-pat-allocate-split-page-tables-as-kernel-page-tables.patch
mm-introduce-vma_flags_can_grow-and-vma_can_grow.patch
mm-vma-update-do_mmap-to-use-vma_flags_t.patch
mm-convert-__get_unmapped_area-to-use-vma_flags_t.patch
mm-update-generic_get_unmapped_area-to-use-vma_flags_t.patch
mm-prefer-mm-def_vma_flags-in-mm-logic.patch
mm-vma-convert-vm_pgprot_modify-to-use-vma_flags_t-and-rename.patch
mm-vma-rename-vma_get_page_prot-to-vma_flags_to_page_prot.patch
mm-introduce-vma_get_page_prot-and-use-it.patch
mm-vma-update-create_init_stack_vma-to-use-vma_flags_t.patch
mm-vma-convert-miscellaneous-uses-of-vma-flags-in-core-mm.patch
mm-mlock-convert-mlock-code-to-use-vma_flags_t.patch
mm-mprotect-convert-mprotect-code-to-use-vma_flags_t.patch
mm-mremap-convert-mremap-code-to-use-vma_flags_t.patch
mm-mseal-remove-superfluous-comments-fix-confusion-around-mm.patch
mm-mseal-limit-scope-of-mseal-address-zero-to-address-zero.patch
mm-mseal-remove-further-superfluous-comments-do_mseal.patch
mm-vma-introduce-vma-anon-page-offset-field-and-add-helpers.patch
mm-provide-vma_is_cow_mapping-and-remove-is_cow_mapping.patch
mm-introduce-linear_anon_page_index.patch
mm-abstract-vma_address-and-introduce-vma_anon_address.patch
mm-update-print_bad_page_map-to-show-anon-index-if-appropriate.patch
mm-introduce-and-use-vma_filebacked_address.patch
mm-vma-fix-self-merge-check-in-copy_vma.patch
tools-testing-vma-add-tests-for-copy_vma-self-merge.patch
mm-propagate-vma-anonymous-page-offset-on-map-remap-split-merge.patch
mm-rmap-track-whether-the-page-vma-mapped-pgoff-is-anonymous.patch
mm-clean-up-vma_address_end.patch
mm-huge_memory-update-remove_migration_pmd-to-accept-a-folio.patch
mm-migrate-calculate-large-folio-page-index-using-pfn.patch
mm-rmap-use-anon-pgoff-to-track-map_private-file-backed-anon-folios.patch
tools-testing-vma-expand-vma-merge-tests-to-assert-anon-pgoff.patch
tools-testing-selftests-mm-test-anonymous-page-offset-merge-behaviour.patch
mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch
mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch
mm-add-some-missing-includes-to-mm-local-headers.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
* + tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch added to mm-unstable branch
@ 2026-09-08 23:46 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-09-08 23:46 UTC (permalink / raw)
To: mm-commits, ljs, akpm
The patch titled
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
has been added to the -mm mm-unstable branch. Its filename is
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
Date: Tue, 08 Sep 2026 12:23:42 +0100
Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add
a VMA userland test to assert that this is the case and everything is as
we would expect for an anonymous mapping.
Link: https://lore.kernel.org/20260908-map-private-dev-zero-v2-5-acc7b5625305@kernel.org
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/vma/tests/mmap.c | 37 +++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
--- a/tools/testing/vma/tests/mmap.c~tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon
+++ a/tools/testing/vma/tests/mmap.c
@@ -45,7 +45,44 @@ static bool test_mmap_region_basic(void)
return true;
}
+static bool test_pure_anon_dev_zero(void)
+{
+ const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
+ VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
+ struct file file = {
+ .f_op = &zero_fops,
+ };
+ struct mm_struct mm = {};
+ struct vm_area_struct *vma;
+ unsigned long addr;
+ VMA_ITERATOR(vmi, &mm, 0);
+
+ current->mm = &mm;
+
+ /*
+ * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page
+ * offset of 0x10, which we expect to be reset to the anonymous page
+ * offset.
+ */
+ addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL);
+ ASSERT_EQ(addr, 0x300000);
+
+ /* Assert that it truly is an anonymous mapping. */
+ vma = vma_lookup(&mm, addr);
+ ASSERT_NE(vma, NULL);
+ ASSERT_TRUE(vma_is_anonymous(vma));
+ ASSERT_EQ(vma->vm_file, NULL);
+ ASSERT_EQ(vma->vm_private_data, NULL);
+ /* Expect anonymous page offsets. */
+ ASSERT_EQ(vma->vm_pgoff, 0x300);
+ ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300);
+
+ cleanup_mm(&mm, &vmi);
+ return true;
+}
+
static void run_mmap_tests(int *num_tests, int *num_fail)
{
TEST(mmap_region_basic);
+ TEST(pure_anon_dev_zero);
}
_
Patches currently in -mm which might be from ljs@kernel.org are
mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch
mm-vmpressure-remove-window-size-todo.patch
tools-testing-selftests-mm-add-missing-gitignore-entries.patch
mm-move-drivers-char-memc-to-mm-char-memc.patch
mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch
mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch
mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch
mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch
mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch
mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch
mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch
mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch
mm-make-userland-page-table-freeing-rcu-safe.patch
mm-change-the-contract-for-free_pgtables-update-docs.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
* + tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch added to mm-unstable branch
@ 2026-09-27 21:55 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-09-27 21:55 UTC (permalink / raw)
To: mm-commits, ljs, akpm
The patch titled
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
has been added to the -mm mm-unstable branch. Its filename is
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
Date: Tue, 08 Sep 2026 12:23:42 +0100
Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add
a VMA userland test to assert that this is the case and everything is as
we would expect for an anonymous mapping.
Link: https://lore.kernel.org/20260908-map-private-dev-zero-v2-5-acc7b5625305@kernel.org
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
---
tools/testing/vma/tests/mmap.c | 37 +++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
--- a/tools/testing/vma/tests/mmap.c~tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon
+++ a/tools/testing/vma/tests/mmap.c
@@ -45,7 +45,44 @@ static bool test_mmap_region_basic(void)
return true;
}
+static bool test_pure_anon_dev_zero(void)
+{
+ const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
+ VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
+ struct file file = {
+ .f_op = &zero_fops,
+ };
+ struct mm_struct mm = {};
+ struct vm_area_struct *vma;
+ unsigned long addr;
+ VMA_ITERATOR(vmi, &mm, 0);
+
+ current->mm = &mm;
+
+ /*
+ * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page
+ * offset of 0x10, which we expect to be reset to the anonymous page
+ * offset.
+ */
+ addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL);
+ ASSERT_EQ(addr, 0x300000);
+
+ /* Assert that it truly is an anonymous mapping. */
+ vma = vma_lookup(&mm, addr);
+ ASSERT_NE(vma, NULL);
+ ASSERT_TRUE(vma_is_anonymous(vma));
+ ASSERT_EQ(vma->vm_file, NULL);
+ ASSERT_EQ(vma->vm_private_data, NULL);
+ /* Expect anonymous page offsets. */
+ ASSERT_EQ(vma->vm_pgoff, 0x300);
+ ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300);
+
+ cleanup_mm(&mm, &vmi);
+ return true;
+}
+
static void run_mmap_tests(int *num_tests, int *num_fail)
{
TEST(mmap_region_basic);
+ TEST(pure_anon_dev_zero);
}
_
Patches currently in -mm which might be from ljs@kernel.org are
mm-mremap-fix-locked_vm-leak-from-mremap_dontunmap-self-merge.patch
mm-mremap-fix-locked_vm-leak-by-splitting-vma-for-mremap_dontunmap.patch
mm-vmpressure-remove-window-size-todo.patch
tools-testing-selftests-mm-add-missing-gitignore-entries.patch
mm-move-drivers-char-memc-to-mm-char-memc.patch
mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch
mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch
mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch
mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch
mm-khugepaged-deposit-a-newly-allocated-page-table-on-collapse.patch
mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch
mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch
mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch
mm-userland-pgtable-freeing-is-rcu-safe-now-remove-leftover-bits.patch
mm-change-the-contract-for-free_pgtables-update-docs.patch
mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch
mm-vma-introduce-and-use-vma_can_merge.patch
mm-consistently-validate-vma-state-after-mmap-hooks.patch
mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch
mm-make-map_kernel_pages_-internal-and-unexported.patch
mm-vma-tidy-up-map-kernel-pages-enum-values.patch
mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch
docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch
drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch
infiniband-update-hfi1-to-use-remap_vmalloc_range.patch
selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch
alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch
bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch
mm-vma-add-vma_is_kernel_owned-predicates.patch
mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch
mm-vma-add-and-use-vma__is_fixed_mapping.patch
scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch
fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch
hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch
mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch
uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch
mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch
mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch
mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch
mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch
mm-remove-hugetlb_inlineh.patch
mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch
mm-drop-some-redundant-checks-around-hugetlb-vmas.patch
mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch
mm-vma-introduce-vma_is_persistent.patch
mm-uffd-use-predicates-for-userfaultfd-checks.patch
mm-madvise-use-predicates-for-madvise-madv_dofork.patch
mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch
mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch
mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch
mm-eliminate-vm_special-vma_special_flags.patch
fuse-dax-do-not-set-vm_mixedmap.patch
mm-huge_memory-remove-vma_is_special_huge.patch
mm-vma-introduce-and-use-vma_can_gup.patch
mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch
mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch
mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch
mm-vma-dont-remove-vma-from-rmap-if-pgoff-unchanged.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
* + tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch added to mm-unstable branch
@ 2026-09-28 23:40 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-09-28 23:40 UTC (permalink / raw)
To: mm-commits, ljs, akpm
The patch titled
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
has been added to the -mm mm-unstable branch. Its filename is
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon
Date: Sat, 26 Sep 2026 11:41:10 +0100
Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add a
VMA userland test to assert that this is the case and everything is as we
would expect for an anonymous mapping.
Link: https://lore.kernel.org/20260926-map-private-dev-zero-v3-5-d4781e84ccfc@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
---
tools/testing/vma/tests/mmap.c | 37 +++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
--- a/tools/testing/vma/tests/mmap.c~tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon
+++ a/tools/testing/vma/tests/mmap.c
@@ -45,7 +45,44 @@ static bool test_mmap_region_basic(void)
return true;
}
+static bool test_pure_anon_dev_zero(void)
+{
+ const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
+ VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
+ struct file file = {
+ .f_op = &zero_fops,
+ };
+ struct mm_struct mm = {};
+ struct vm_area_struct *vma;
+ unsigned long addr;
+ VMA_ITERATOR(vmi, &mm, 0);
+
+ current->mm = &mm;
+
+ /*
+ * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page
+ * offset of 0x10, which we expect to be reset to the anonymous page
+ * offset.
+ */
+ addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL);
+ ASSERT_EQ(addr, 0x300000);
+
+ /* Assert that it truly is an anonymous mapping. */
+ vma = vma_lookup(&mm, addr);
+ ASSERT_NE(vma, NULL);
+ ASSERT_TRUE(vma_is_anonymous(vma));
+ ASSERT_EQ(vma->vm_file, NULL);
+ ASSERT_EQ(vma->vm_private_data, NULL);
+ /* Expect anonymous page offsets. */
+ ASSERT_EQ(vma->vm_pgoff, 0x300);
+ ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300);
+
+ cleanup_mm(&mm, &vmi);
+ return true;
+}
+
static void run_mmap_tests(int *num_tests, int *num_fail)
{
TEST(mmap_region_basic);
+ TEST(pure_anon_dev_zero);
}
_
Patches currently in -mm which might be from ljs@kernel.org are
mm-mremap-fix-locked_vm-leak-from-mremap_dontunmap-self-merge.patch
mm-mremap-fix-locked_vm-leak-by-splitting-vma-for-mremap_dontunmap.patch
mm-vmpressure-remove-window-size-todo.patch
tools-testing-selftests-mm-add-missing-gitignore-entries.patch
mm-move-drivers-char-memc-to-mm-char-memc.patch
mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch
mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch
mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch
mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch
mm-khugepaged-deposit-a-newly-allocated-page-table-on-collapse.patch
mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch
mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch
mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch
mm-userland-pgtable-freeing-is-rcu-safe-now-remove-leftover-bits.patch
mm-change-the-contract-for-free_pgtables-update-docs.patch
mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch
mm-vma-introduce-and-use-vma_can_merge.patch
mm-consistently-validate-vma-state-after-mmap-hooks.patch
mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch
mm-make-map_kernel_pages_-internal-and-unexported.patch
mm-vma-tidy-up-map-kernel-pages-enum-values.patch
mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch
docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch
drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch
infiniband-update-hfi1-to-use-remap_vmalloc_range.patch
selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch
alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch
bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch
mm-vma-add-vma_is_kernel_owned-predicates.patch
mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch
mm-vma-add-and-use-vma__is_fixed_mapping.patch
scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch
fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch
hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch
mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch
uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch
mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch
mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch
mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch
mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch
mm-remove-hugetlb_inlineh.patch
mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch
mm-drop-some-redundant-checks-around-hugetlb-vmas.patch
mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch
mm-vma-introduce-vma_is_persistent.patch
mm-uffd-use-predicates-for-userfaultfd-checks.patch
mm-madvise-use-predicates-for-madvise-madv_dofork.patch
mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch
mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch
mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch
mm-eliminate-vm_special-vma_special_flags.patch
fuse-dax-do-not-set-vm_mixedmap.patch
mm-huge_memory-remove-vma_is_special_huge.patch
mm-vma-introduce-and-use-vma_can_gup.patch
mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch
mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch
mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch
mm-vma-dont-remove-vma-from-rmap-if-pgoff-unchanged.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
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