* [PATCH 1/2] vdso/timens: Move functions to new file
2026-03-23 8:07 [PATCH 0/2] timens: Remove dependency on the vDSO Thomas Weißschuh
@ 2026-03-23 8:07 ` Thomas Weißschuh
2026-03-24 19:36 ` Thomas Gleixner
2026-03-23 8:07 ` [PATCH 2/2] timens: Remove dependency on the vDSO Thomas Weißschuh
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Weißschuh @ 2026-03-23 8:07 UTC (permalink / raw)
To: Anna-Maria Behnsen, Frederic Weisbecker, Thomas Gleixner,
Andy Lutomirski, Vincenzo Frascino
Cc: linux-kernel, Thomas Weißschuh
As a preparation of the untangling of time namespaces and the vDSO, move
the glue functions between those subsystems into a new file.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
MAINTAINERS | 2 +
include/linux/time_namespace.h | 8 ---
kernel/time/Makefile | 2 +-
kernel/time/namespace.c | 124 ++------------------------------
kernel/time/namespace_internal.h | 13 ++++
kernel/time/namespace_vdso.c | 150 +++++++++++++++++++++++++++++++++++++++
lib/vdso/datastore.c | 25 -------
7 files changed, 170 insertions(+), 154 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index 77fdfcb55f06..6ad74a5196d1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10768,6 +10768,7 @@ S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso
F: include/asm-generic/vdso/vsyscall.h
F: include/vdso/
+F: kernel/time/namespace_vdso.c
F: kernel/time/vsyscall.c
F: lib/vdso/
F: tools/testing/selftests/vDSO/
@@ -21000,6 +21001,7 @@ F: include/trace/events/timer*
F: kernel/time/itimer.c
F: kernel/time/posix-*
F: kernel/time/namespace.c
+F: kernel/time/namespace_vdso.c
POWER MANAGEMENT CORE
M: "Rafael J. Wysocki" <rafael@kernel.org>
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index c514d0e5a45c..0421bf1b13d7 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -38,8 +38,6 @@ static inline struct time_namespace *to_time_ns(struct ns_common *ns)
return container_of(ns, struct time_namespace, ns);
}
void __init time_ns_init(void);
-extern int vdso_join_timens(struct task_struct *task,
- struct time_namespace *ns);
extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
@@ -117,12 +115,6 @@ static inline void __init time_ns_init(void)
{
}
-static inline int vdso_join_timens(struct task_struct *task,
- struct time_namespace *ns)
-{
- return 0;
-}
-
static inline void timens_commit(struct task_struct *tsk,
struct time_namespace *ns)
{
diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index f7d52d9543cc..662bccb3b7f9 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -29,6 +29,6 @@ endif
obj-$(CONFIG_GENERIC_GETTIMEOFDAY) += vsyscall.o
obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o
obj-$(CONFIG_TEST_UDELAY) += test_udelay.o
-obj-$(CONFIG_TIME_NS) += namespace.o
+obj-$(CONFIG_TIME_NS) += namespace.o namespace_vdso.o
obj-$(CONFIG_TEST_CLOCKSOURCE_WATCHDOG) += clocksource-wdtest.o
obj-$(CONFIG_TIME_KUNIT_TEST) += time_test.o
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 652744e00eb4..903f55a2dfb2 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -19,7 +19,7 @@
#include <linux/err.h>
#include <linux/mm.h>
-#include <vdso/datapage.h>
+#include "namespace_internal.h"
ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
struct timens_offsets *ns_offsets)
@@ -138,117 +138,7 @@ struct time_namespace *copy_time_ns(u64 flags,
return clone_time_ns(user_ns, old_ns);
}
-static struct timens_offset offset_from_ts(struct timespec64 off)
-{
- struct timens_offset ret;
-
- ret.sec = off.tv_sec;
- ret.nsec = off.tv_nsec;
-
- return ret;
-}
-
-/*
- * A time namespace VVAR page has the same layout as the VVAR page which
- * contains the system wide VDSO data.
- *
- * For a normal task the VVAR pages are installed in the normal ordering:
- * VVAR
- * PVCLOCK
- * HVCLOCK
- * TIMENS <- Not really required
- *
- * Now for a timens task the pages are installed in the following order:
- * TIMENS
- * PVCLOCK
- * HVCLOCK
- * VVAR
- *
- * The check for vdso_clock->clock_mode is in the unlikely path of
- * the seq begin magic. So for the non-timens case most of the time
- * 'seq' is even, so the branch is not taken.
- *
- * If 'seq' is odd, i.e. a concurrent update is in progress, the extra check
- * for vdso_clock->clock_mode is a non-issue. The task is spin waiting for the
- * update to finish and for 'seq' to become even anyway.
- *
- * Timens page has vdso_clock->clock_mode set to VDSO_CLOCKMODE_TIMENS which
- * enforces the time namespace handling path.
- */
-static void timens_setup_vdso_clock_data(struct vdso_clock *vc,
- struct time_namespace *ns)
-{
- struct timens_offset *offset = vc->offset;
- struct timens_offset monotonic = offset_from_ts(ns->offsets.monotonic);
- struct timens_offset boottime = offset_from_ts(ns->offsets.boottime);
-
- vc->seq = 1;
- vc->clock_mode = VDSO_CLOCKMODE_TIMENS;
- offset[CLOCK_MONOTONIC] = monotonic;
- offset[CLOCK_MONOTONIC_RAW] = monotonic;
- offset[CLOCK_MONOTONIC_COARSE] = monotonic;
- offset[CLOCK_BOOTTIME] = boottime;
- offset[CLOCK_BOOTTIME_ALARM] = boottime;
-}
-
-struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- if (likely(vma->vm_mm == current->mm))
- return current->nsproxy->time_ns->vvar_page;
-
- /*
- * VM_PFNMAP | VM_IO protect .fault() handler from being called
- * through interfaces like /proc/$pid/mem or
- * process_vm_{readv,writev}() as long as there's no .access()
- * in special_mapping_vmops().
- * For more details check_vma_flags() and __access_remote_vm()
- */
-
- WARN(1, "vvar_page accessed remotely");
-
- return NULL;
-}
-
-/*
- * Protects possibly multiple offsets writers racing each other
- * and tasks entering the namespace.
- */
-static DEFINE_MUTEX(offset_lock);
-
-static void timens_set_vvar_page(struct task_struct *task,
- struct time_namespace *ns)
-{
- struct vdso_time_data *vdata;
- struct vdso_clock *vc;
- unsigned int i;
-
- if (ns == &init_time_ns)
- return;
-
- /* Fast-path, taken by every task in namespace except the first. */
- if (likely(ns->frozen_offsets))
- return;
-
- mutex_lock(&offset_lock);
- /* Nothing to-do: vvar_page has been already initialized. */
- if (ns->frozen_offsets)
- goto out;
-
- ns->frozen_offsets = true;
- vdata = page_address(ns->vvar_page);
- vc = vdata->clock_data;
-
- for (i = 0; i < CS_BASES; i++)
- timens_setup_vdso_clock_data(&vc[i], ns);
-
- if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS)) {
- for (i = 0; i < ARRAY_SIZE(vdata->aux_clock_data); i++)
- timens_setup_vdso_clock_data(&vdata->aux_clock_data[i], ns);
- }
-
-out:
- mutex_unlock(&offset_lock);
-}
+DEFINE_MUTEX(timens_offset_lock);
void free_time_ns(struct time_namespace *ns)
{
@@ -298,12 +188,6 @@ static void timens_put(struct ns_common *ns)
put_time_ns(to_time_ns(ns));
}
-void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
-{
- timens_set_vvar_page(tsk, ns);
- vdso_join_timens(tsk, ns);
-}
-
static int timens_install(struct nsset *nsset, struct ns_common *new)
{
struct nsproxy *nsproxy = nsset->nsproxy;
@@ -428,7 +312,7 @@ int proc_timens_set_offset(struct file *file, struct task_struct *p,
goto out;
}
- mutex_lock(&offset_lock);
+ mutex_lock(&timens_offset_lock);
if (time_ns->frozen_offsets) {
err = -EACCES;
goto out_unlock;
@@ -453,7 +337,7 @@ int proc_timens_set_offset(struct file *file, struct task_struct *p,
}
out_unlock:
- mutex_unlock(&offset_lock);
+ mutex_unlock(&timens_offset_lock);
out:
put_time_ns(time_ns);
diff --git a/kernel/time/namespace_internal.h b/kernel/time/namespace_internal.h
new file mode 100644
index 000000000000..e85da11abb4d
--- /dev/null
+++ b/kernel/time/namespace_internal.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TIME_NAMESPACE_INTERNAL_H
+#define _TIME_NAMESPACE_INTERNAL_H
+
+#include <linux/mutex.h>
+
+/*
+ * Protects possibly multiple offsets writers racing each other
+ * and tasks entering the namespace.
+ */
+extern struct mutex timens_offset_lock;
+
+#endif /* _TIME_NAMESPACE_INTERNAL_H */
diff --git a/kernel/time/namespace_vdso.c b/kernel/time/namespace_vdso.c
new file mode 100644
index 000000000000..96d07b60ebaf
--- /dev/null
+++ b/kernel/time/namespace_vdso.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Andrei Vagin <avagin@openvz.org>
+ * Author: Dmitry Safonov <dima@arista.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/time_namespace.h>
+#include <linux/time.h>
+#include <linux/vdso_datastore.h>
+
+#include <vdso/clocksource.h>
+#include <vdso/datapage.h>
+
+#include "namespace_internal.h"
+
+static struct timens_offset offset_from_ts(struct timespec64 off)
+{
+ struct timens_offset ret;
+
+ ret.sec = off.tv_sec;
+ ret.nsec = off.tv_nsec;
+
+ return ret;
+}
+
+/*
+ * A time namespace VVAR page has the same layout as the VVAR page which
+ * contains the system wide VDSO data.
+ *
+ * For a normal task the VVAR pages are installed in the normal ordering:
+ * VVAR
+ * PVCLOCK
+ * HVCLOCK
+ * TIMENS <- Not really required
+ *
+ * Now for a timens task the pages are installed in the following order:
+ * TIMENS
+ * PVCLOCK
+ * HVCLOCK
+ * VVAR
+ *
+ * The check for vdso_clock->clock_mode is in the unlikely path of
+ * the seq begin magic. So for the non-timens case most of the time
+ * 'seq' is even, so the branch is not taken.
+ *
+ * If 'seq' is odd, i.e. a concurrent update is in progress, the extra check
+ * for vdso_clock->clock_mode is a non-issue. The task is spin waiting for the
+ * update to finish and for 'seq' to become even anyway.
+ *
+ * Timens page has vdso_clock->clock_mode set to VDSO_CLOCKMODE_TIMENS which
+ * enforces the time namespace handling path.
+ */
+static void timens_setup_vdso_clock_data(struct vdso_clock *vc,
+ struct time_namespace *ns)
+{
+ struct timens_offset *offset = vc->offset;
+ struct timens_offset monotonic = offset_from_ts(ns->offsets.monotonic);
+ struct timens_offset boottime = offset_from_ts(ns->offsets.boottime);
+
+ vc->seq = 1;
+ vc->clock_mode = VDSO_CLOCKMODE_TIMENS;
+ offset[CLOCK_MONOTONIC] = monotonic;
+ offset[CLOCK_MONOTONIC_RAW] = monotonic;
+ offset[CLOCK_MONOTONIC_COARSE] = monotonic;
+ offset[CLOCK_BOOTTIME] = boottime;
+ offset[CLOCK_BOOTTIME_ALARM] = boottime;
+}
+
+struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_mm == current->mm))
+ return current->nsproxy->time_ns->vvar_page;
+
+ /*
+ * VM_PFNMAP | VM_IO protect .fault() handler from being called
+ * through interfaces like /proc/$pid/mem or
+ * process_vm_{readv,writev}() as long as there's no .access()
+ * in special_mapping_vmops().
+ * For more details check_vma_flags() and __access_remote_vm()
+ */
+
+ WARN(1, "vvar_page accessed remotely");
+
+ return NULL;
+}
+
+static void timens_set_vvar_page(struct task_struct *task,
+ struct time_namespace *ns)
+{
+ struct vdso_time_data *vdata;
+ struct vdso_clock *vc;
+ unsigned int i;
+
+ if (ns == &init_time_ns)
+ return;
+
+ /* Fast-path, taken by every task in namespace except the first. */
+ if (likely(ns->frozen_offsets))
+ return;
+
+ mutex_lock(&timens_offset_lock);
+ /* Nothing to-do: vvar_page has been already initialized. */
+ if (ns->frozen_offsets)
+ goto out;
+
+ ns->frozen_offsets = true;
+ vdata = page_address(ns->vvar_page);
+ vc = vdata->clock_data;
+
+ for (i = 0; i < CS_BASES; i++)
+ timens_setup_vdso_clock_data(&vc[i], ns);
+
+ if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS)) {
+ for (i = 0; i < ARRAY_SIZE(vdata->aux_clock_data); i++)
+ timens_setup_vdso_clock_data(&vdata->aux_clock_data[i], ns);
+ }
+
+out:
+ mutex_unlock(&timens_offset_lock);
+}
+
+/*
+ * The vvar page layout depends on whether a task belongs to the root or
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
+ * page tables are cleared and then they will be re-faulted with a
+ * corresponding layout.
+ * See also the comment near timens_setup_vdso_clock_data() for details.
+ */
+static int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+ struct mm_struct *mm = task->mm;
+ struct vm_area_struct *vma;
+ VMA_ITERATOR(vmi, mm, 0);
+
+ mmap_read_lock(mm);
+ for_each_vma(vmi, vma) {
+ if (vma_is_special_mapping(vma, &vdso_vvar_mapping))
+ zap_vma_pages(vma);
+ }
+ mmap_read_unlock(mm);
+
+ return 0;
+}
+
+void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
+{
+ timens_set_vvar_page(tsk, ns);
+ vdso_join_timens(tsk, ns);
+}
diff --git a/lib/vdso/datastore.c b/lib/vdso/datastore.c
index faebf5b7cd6e..cf5d784a4a5a 100644
--- a/lib/vdso/datastore.c
+++ b/lib/vdso/datastore.c
@@ -132,28 +132,3 @@ struct vm_area_struct *vdso_install_vvar_mapping(struct mm_struct *mm, unsigned
VM_MIXEDMAP | VM_SEALED_SYSMAP,
&vdso_vvar_mapping);
}
-
-#ifdef CONFIG_TIME_NS
-/*
- * The vvar page layout depends on whether a task belongs to the root or
- * non-root time namespace. Whenever a task changes its namespace, the VVAR
- * page tables are cleared and then they will be re-faulted with a
- * corresponding layout.
- * See also the comment near timens_setup_vdso_clock_data() for details.
- */
-int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
-{
- struct mm_struct *mm = task->mm;
- struct vm_area_struct *vma;
- VMA_ITERATOR(vmi, mm, 0);
-
- mmap_read_lock(mm);
- for_each_vma(vmi, vma) {
- if (vma_is_special_mapping(vma, &vdso_vvar_mapping))
- zap_vma_pages(vma);
- }
- mmap_read_unlock(mm);
-
- return 0;
-}
-#endif
--
2.53.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 2/2] timens: Remove dependency on the vDSO
2026-03-23 8:07 [PATCH 0/2] timens: Remove dependency on the vDSO Thomas Weißschuh
2026-03-23 8:07 ` [PATCH 1/2] vdso/timens: Move functions to new file Thomas Weißschuh
@ 2026-03-23 8:07 ` Thomas Weißschuh
1 sibling, 0 replies; 5+ messages in thread
From: Thomas Weißschuh @ 2026-03-23 8:07 UTC (permalink / raw)
To: Anna-Maria Behnsen, Frederic Weisbecker, Thomas Gleixner,
Andy Lutomirski, Vincenzo Frascino
Cc: linux-kernel, Thomas Weißschuh
Previously, missing time namespace support in the vDSO meant that time
namespaces needed to be disabled globally. This was expressed in a hard
dependency on the generic vDSO library. This also meant that architectures
without any vDSO or only a stub vDSO could not enable time namespaces.
Now that all architectures using a real vDSO are using the generic library,
that dependency is not necessary anymore.
Remove the dependency and let all architectures enable time namespaces.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
include/linux/time_namespace.h | 28 ++++++++++++++++------------
init/Kconfig | 4 +++-
kernel/time/Makefile | 3 ++-
kernel/time/namespace.c | 8 ++++----
kernel/time/namespace_internal.h | 15 +++++++++++++++
kernel/time/namespace_vdso.c | 14 ++++++++++++++
6 files changed, 54 insertions(+), 18 deletions(-)
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 0421bf1b13d7..c1de21a27c34 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -25,7 +25,9 @@ struct time_namespace {
struct ucounts *ucounts;
struct ns_common ns;
struct timens_offsets offsets;
+#ifdef CONFIG_TIME_NS_VDSO
struct page *vvar_page;
+#endif
/* If set prevents changing offsets after any task joined namespace. */
bool frozen_offsets;
} __randomize_layout;
@@ -38,7 +40,6 @@ static inline struct time_namespace *to_time_ns(struct ns_common *ns)
return container_of(ns, struct time_namespace, ns);
}
void __init time_ns_init(void);
-extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
{
@@ -51,7 +52,6 @@ struct time_namespace *copy_time_ns(u64 flags,
struct time_namespace *old_ns);
void free_time_ns(struct time_namespace *ns);
void timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
-struct page *find_timens_vvar_page(struct vm_area_struct *vma);
static inline void put_time_ns(struct time_namespace *ns)
{
@@ -115,11 +115,6 @@ static inline void __init time_ns_init(void)
{
}
-static inline void timens_commit(struct task_struct *tsk,
- struct time_namespace *ns)
-{
-}
-
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
{
return NULL;
@@ -146,11 +141,6 @@ static inline void timens_on_fork(struct nsproxy *nsproxy,
return;
}
-static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- return NULL;
-}
-
static inline void timens_add_monotonic(struct timespec64 *ts) { }
static inline void timens_add_boottime(struct timespec64 *ts) { }
@@ -167,4 +157,18 @@ static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
}
#endif
+#ifdef CONFIG_TIME_NS_VDSO
+extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
+struct page *find_timens_vvar_page(struct vm_area_struct *vma);
+#else /* !CONFIG_TIME_NS_VDSO */
+static inline void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
+{
+}
+
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+ return NULL;
+}
+#endif /* CONFIG_TIME_NS_VDSO */
+
#endif /* _LINUX_TIMENS_H */
diff --git a/init/Kconfig b/init/Kconfig
index 444ce811ea67..5e710b03a27a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1386,12 +1386,14 @@ config UTS_NS
config TIME_NS
bool "TIME namespace"
- depends on GENERIC_GETTIMEOFDAY
default y
help
In this namespace boottime and monotonic clocks can be set.
The time will keep going with the same pace.
+config TIME_NS_VDSO
+ def_bool TIME_NS && GENERIC_GETTIMEOFDAY
+
config IPC_NS
bool "IPC namespace"
depends on (SYSVIPC || POSIX_MQUEUE)
diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index 662bccb3b7f9..eaf290c972f9 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -29,6 +29,7 @@ endif
obj-$(CONFIG_GENERIC_GETTIMEOFDAY) += vsyscall.o
obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o
obj-$(CONFIG_TEST_UDELAY) += test_udelay.o
-obj-$(CONFIG_TIME_NS) += namespace.o namespace_vdso.o
+obj-$(CONFIG_TIME_NS) += namespace.o
+obj-$(CONFIG_TIME_NS_VDSO) += namespace_vdso.o
obj-$(CONFIG_TEST_CLOCKSOURCE_WATCHDOG) += clocksource-wdtest.o
obj-$(CONFIG_TIME_KUNIT_TEST) += time_test.o
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 903f55a2dfb2..42302cc3f3fb 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -93,8 +93,8 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
if (!ns)
goto fail_dec;
- ns->vvar_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
- if (!ns->vvar_page)
+ err = timens_vdso_alloc_vvar_page(ns);
+ if (err)
goto fail_free;
err = ns_common_init(ns);
@@ -109,7 +109,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
return ns;
fail_free_page:
- __free_page(ns->vvar_page);
+ timens_vdso_free_vvar_page(ns);
fail_free:
kfree(ns);
fail_dec:
@@ -146,7 +146,7 @@ void free_time_ns(struct time_namespace *ns)
dec_time_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
ns_common_free(ns);
- __free_page(ns->vvar_page);
+ timens_vdso_free_vvar_page(ns);
/* Concurrent nstree traversal depends on a grace period. */
kfree_rcu(ns, ns.ns_rcu);
}
diff --git a/kernel/time/namespace_internal.h b/kernel/time/namespace_internal.h
index e85da11abb4d..b37ba179f43b 100644
--- a/kernel/time/namespace_internal.h
+++ b/kernel/time/namespace_internal.h
@@ -4,10 +4,25 @@
#include <linux/mutex.h>
+struct time_namespace;
+
/*
* Protects possibly multiple offsets writers racing each other
* and tasks entering the namespace.
*/
extern struct mutex timens_offset_lock;
+#ifdef CONFIG_TIME_NS_VDSO
+int timens_vdso_alloc_vvar_page(struct time_namespace *ns);
+void timens_vdso_free_vvar_page(struct time_namespace *ns);
+#else /* !CONFIG_TIME_NS_VDSO */
+static inline int timens_vdso_alloc_vvar_page(struct time_namespace *ns)
+{
+ return 0;
+}
+static inline void timens_vdso_free_vvar_page(struct time_namespace *ns)
+{
+}
+#endif /* CONFIG_TIME_NS_VDSO */
+
#endif /* _TIME_NAMESPACE_INTERNAL_H */
diff --git a/kernel/time/namespace_vdso.c b/kernel/time/namespace_vdso.c
index 96d07b60ebaf..4ab0d89ad9e0 100644
--- a/kernel/time/namespace_vdso.c
+++ b/kernel/time/namespace_vdso.c
@@ -148,3 +148,17 @@ void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
timens_set_vvar_page(tsk, ns);
vdso_join_timens(tsk, ns);
}
+
+int timens_vdso_alloc_vvar_page(struct time_namespace *ns)
+{
+ ns->vvar_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+ if (!ns->vvar_page)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void timens_vdso_free_vvar_page(struct time_namespace *ns)
+{
+ __free_page(ns->vvar_page);
+}
--
2.53.0
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