* + selftests-mm-verify-droppable-mappings-cannot-be-locked.patch added to mm-new branch
@ 2026-03-10 17:32 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-03-10 17:32 UTC (permalink / raw)
To: mm-commits, vbabka, surenb, shuah, rppt, pfalcato, mhocko, ljs,
liam.howlett, jason, jannh, david, anthony.yznaga, akpm
The patch titled
Subject: selftests/mm: verify droppable mappings cannot be locked
has been added to the -mm mm-new branch. Its filename is
selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
The mm-new branch of mm.git is not included in linux-next
If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next
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: Anthony Yznaga <anthony.yznaga@oracle.com>
Subject: selftests/mm: verify droppable mappings cannot be locked
Date: Tue, 10 Mar 2026 08:58:21 -0700
Verify that a mapping created with MAP_DROPPABLE cannot be locked via
mlock(), and that it will not be locked if it's created after
mlockall(MCL_FUTURE).
Link: https://lkml.kernel.org/r/20260310155821.17869-2-anthony.yznaga@oracle.com
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/selftests/mm/mlock2-tests.c | 78 +++++++++++++++++---
1 file changed, 69 insertions(+), 9 deletions(-)
--- a/tools/testing/selftests/mm/mlock2-tests.c~selftests-mm-verify-droppable-mappings-cannot-be-locked
+++ a/tools/testing/selftests/mm/mlock2-tests.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <sys/mman.h>
+#include <linux/mman.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
@@ -163,14 +164,17 @@ static int lock_check(unsigned long addr
return (vma_rss == vma_size);
}
-static int unlock_lock_check(char *map)
+static int unlock_lock_check(char *map, bool mlock_supported)
{
- if (is_vmflag_set((unsigned long)map, LOCKED)) {
+ if (!is_vmflag_set((unsigned long)map, LOCKED))
+ return 0;
+
+ if (mlock_supported)
ksft_print_msg("VMA flag %s is present on page 1 after unlock\n", LOCKED);
- return 1;
- }
+ else
+ ksft_print_msg("VMA flag %s is present on an unsupported VMA\n", LOCKED);
- return 0;
+ return 1;
}
static void test_mlock_lock(void)
@@ -196,7 +200,7 @@ static void test_mlock_lock(void)
ksft_exit_fail_msg("munlock(): %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: Unlocked\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: Unlocked\n", __func__);
munmap(map, 2 * page_size);
}
@@ -296,7 +300,7 @@ static void test_munlockall0(void)
ksft_exit_fail_msg("munlockall(): %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
munmap(map, 2 * page_size);
}
@@ -336,7 +340,61 @@ static void test_munlockall1(void)
ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
+ munmap(map, 2 * page_size);
+}
+
+/*
+ * Droppable memory should not be lockable.
+ */
+static void test_mlock_droppable(void)
+{
+ char *map;
+ unsigned long page_size = getpagesize();
+
+ /*
+ * Ensure MCL_FUTURE is not set.
+ */
+ if (mlockall(MCL_CURRENT))
+ ksft_exit_fail_msg("mlockall(MCL_CURRENT): %s\n", strerror(errno));
+ if (munlockall())
+ ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
+
+ map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
+ if (map == MAP_FAILED)
+ ksft_exit_fail_msg("mmap error: %s", strerror(errno));
+
+ if (mlock2_(map, 2 * page_size, 0)) {
+ munmap(map, 2 * page_size);
+ ksft_exit_fail_msg("mlock2(0): %s\n", strerror(errno));
+ }
+
+ ksft_test_result(!unlock_lock_check(map, false), "%s: droppable memory not locked\n",
+ __func__);
+
+ munmap(map, 2 * page_size);
+}
+
+static void test_mlockall_future_droppable(void)
+{
+ char *map;
+ unsigned long page_size = getpagesize();
+
+ if (mlockall(MCL_CURRENT | MCL_FUTURE))
+ ksft_exit_fail_msg("mlockall(MCL_CURRENT | MCL_FUTURE): %s\n", strerror(errno));
+
+ map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
+
+ ksft_test_result(!unlock_lock_check(map, false), "%s: droppable memory not locked\n",
+ __func__);
+
+ if (munlockall()) {
+ munmap(map, 2 * page_size);
+ ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
+ }
+
munmap(map, 2 * page_size);
}
@@ -442,7 +500,7 @@ int main(int argc, char **argv)
munmap(map, size);
- ksft_set_plan(13);
+ ksft_set_plan(15);
test_mlock_lock();
test_mlock_onfault();
@@ -451,6 +509,8 @@ int main(int argc, char **argv)
test_lock_onfault_of_present();
test_vma_management(true);
test_mlockall();
+ test_mlock_droppable();
+ test_mlockall_future_droppable();
ksft_finished();
}
_
Patches currently in -mm which might be from anthony.yznaga@oracle.com are
mm-prevent-droppable-mappings-from-being-locked.patch
selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
* + selftests-mm-verify-droppable-mappings-cannot-be-locked.patch added to mm-new branch
@ 2026-04-02 0:46 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-04-02 0:46 UTC (permalink / raw)
To: mm-commits, vbabka, surenb, shuah, rppt, pfalcato, mhocko, ljs,
liam.howlett, jason, jannh, david, anthony.yznaga, akpm
The patch titled
Subject: selftests/mm: verify droppable mappings cannot be locked
has been added to the -mm mm-new branch. Its filename is
selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
The mm-new branch of mm.git is not included in linux-next
If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next
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: Anthony Yznaga <anthony.yznaga@oracle.com>
Subject: selftests/mm: verify droppable mappings cannot be locked
Date: Wed, 1 Apr 2026 17:34:17 -0700
For configs that support MAP_DROPPABLE verify that a mapping created with
MAP_DROPPABLE cannot be locked via mlock(), and that it will not be locked
if it's created after mlockall(MCL_FUTURE).
Link: https://lkml.kernel.org/r/20260402003417.438037-3-anthony.yznaga@oracle.com
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/selftests/mm/mlock2-tests.c | 91 ++++++++++++++++++--
1 file changed, 82 insertions(+), 9 deletions(-)
--- a/tools/testing/selftests/mm/mlock2-tests.c~selftests-mm-verify-droppable-mappings-cannot-be-locked
+++ a/tools/testing/selftests/mm/mlock2-tests.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <sys/mman.h>
+#include <linux/mman.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
@@ -163,14 +164,17 @@ static int lock_check(unsigned long addr
return (vma_rss == vma_size);
}
-static int unlock_lock_check(char *map)
+static int unlock_lock_check(char *map, bool mlock_supported)
{
- if (is_vmflag_set((unsigned long)map, LOCKED)) {
+ if (!is_vmflag_set((unsigned long)map, LOCKED))
+ return 0;
+
+ if (mlock_supported)
ksft_print_msg("VMA flag %s is present on page 1 after unlock\n", LOCKED);
- return 1;
- }
+ else
+ ksft_print_msg("VMA flag %s is present on an unsupported VMA\n", LOCKED);
- return 0;
+ return 1;
}
static void test_mlock_lock(void)
@@ -196,7 +200,7 @@ static void test_mlock_lock(void)
ksft_exit_fail_msg("munlock(): %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: Unlocked\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: Unlocked\n", __func__);
munmap(map, 2 * page_size);
}
@@ -296,7 +300,7 @@ static void test_munlockall0(void)
ksft_exit_fail_msg("munlockall(): %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
munmap(map, 2 * page_size);
}
@@ -336,7 +340,74 @@ static void test_munlockall1(void)
ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
}
- ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
+ ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
+ munmap(map, 2 * page_size);
+}
+
+/*
+ * Droppable memory should not be lockable.
+ */
+static void test_mlock_droppable(void)
+{
+ char *map;
+ unsigned long page_size = getpagesize();
+
+ /*
+ * Ensure MCL_FUTURE is not set.
+ */
+ if (mlockall(MCL_CURRENT))
+ ksft_exit_fail_msg("mlockall(MCL_CURRENT): %s\n", strerror(errno));
+ if (munlockall())
+ ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
+
+ map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
+ if (map == MAP_FAILED) {
+ if (errno == EOPNOTSUPP) {
+ ksft_test_result_skip("%s: MAP_DROPPABLE not supported\n", __func__);
+ return;
+ }
+ ksft_exit_fail_msg("mmap error: %s\n", strerror(errno));
+ }
+
+ if (mlock2_(map, 2 * page_size, 0)) {
+ munmap(map, 2 * page_size);
+ ksft_exit_fail_msg("mlock2(0): %s\n", strerror(errno));
+ }
+
+ ksft_test_result(!unlock_lock_check(map, false), "%s: droppable memory not locked\n",
+ __func__);
+
+ munmap(map, 2 * page_size);
+}
+
+static void test_mlockall_future_droppable(void)
+{
+ char *map;
+ unsigned long page_size = getpagesize();
+
+ if (mlockall(MCL_CURRENT | MCL_FUTURE))
+ ksft_exit_fail_msg("mlockall(MCL_CURRENT | MCL_FUTURE): %s\n", strerror(errno));
+
+ map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
+
+ if (map == MAP_FAILED) {
+ if (errno == EOPNOTSUPP) {
+ ksft_test_result_skip("%s: MAP_DROPPABLE not supported\n", __func__);
+ return;
+ }
+ ksft_exit_fail_msg("mmap error: %s\n", strerror(errno));
+ }
+
+ ksft_test_result(!unlock_lock_check(map, false), "%s: droppable memory not locked\n",
+ __func__);
+
+ if (munlockall()) {
+ munmap(map, 2 * page_size);
+ ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
+ }
+
munmap(map, 2 * page_size);
}
@@ -442,7 +513,7 @@ int main(int argc, char **argv)
munmap(map, size);
- ksft_set_plan(13);
+ ksft_set_plan(15);
test_mlock_lock();
test_mlock_onfault();
@@ -451,6 +522,8 @@ int main(int argc, char **argv)
test_lock_onfault_of_present();
test_vma_management(true);
test_mlockall();
+ test_mlock_droppable();
+ test_mlockall_future_droppable();
ksft_finished();
}
_
Patches currently in -mm which might be from anthony.yznaga@oracle.com are
mm-fix-mmap-errno-value-when-map_droppable-is-not-supported.patch
selftests-mm-verify-droppable-mappings-cannot-be-locked.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
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