Rename "guest_paddr" variables in vm_userspace_mem_region_add() and
vm_mem_add() to KVM's de facto standard "gpa", both for consistency and
to shorten line lengths.
Opportunistically fix the indentation of the
vm_userspace_mem_region_add() declaration.
Link: https://patch.msgid.link/20251007223625.369939-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
There are use cases, for example virtual machine hosts, that create
"persistent" memory regions using memmap= option on x86 or dummy
pmem-region device tree nodes on DT based systems.
Both these options are inflexible because they create static regions and
the layout of the "persistent" memory cannot be adjusted without reboot
and sometimes they even require firmware update.
Add a ramdax driver that allows creation of DIMM devices on top of
E820_TYPE_PRAM regions and devicetree pmem-region nodes.
The DIMMs support label space management on the "device" and provide a
flexible way to access RAM using fsdax and devdax.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20251026153841.752061-2-rppt@kernel.org
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
If the kernel hangs while shutting down, ideally a UART log should
be captured to debug the problem. However if one isn't available,
users can use the pstore functionality to retrieve logs.
Add a document explaining how this works to make it more accessible
to users.
Tested-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/20251025004341.2386868-1-superm1@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cancel and wait for any Dead CT worker to complete before continuing
with device unbinding. Else the worker will end up using resources freed
by the undind operation.
Cc: Zhanjun Dong <zhanjun.dong@intel.com>
Fixes: d2c5a5a926 ("drm/xe/guc: Dead CT helper")
Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://patch.msgid.link/20251103123144.3231829-6-balasubramani.vivekanandan@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
When unbinding wait for any GT reset in progress to complete. Unbinding
will release the mmio mapping but mmio operations are performed during
GT reset causing Kernel panic.
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patch.msgid.link/20251103123144.3231829-5-balasubramani.vivekanandan@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
intel_pstate docs uses standard reST construct (`Section title`_) for
cross-referencing sections (internal linking), rather than for external
links. Incorrect cross-references are not caught when these are written
in that syntax, however (fortunately docutils 0.22 raise duplicate
target warnings that get fixed in cb908f8b0a ("Documentation:
intel_pstate: fix duplicate hyperlink target errors")).
Convert the cross-references to use :ref: directive, which doesn't
exhibit this problem.
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
[ rjw: Changelog tweak ]
Link: https://patch.msgid.link/20251101055614.32270-1-bagasdotme@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
It's just getting an integer from userspace, installing a file, then
copying the output direct descriptor back. No need to use the full
copy_to/from_user() for that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
I started seeing this in recent Fedora 42 kernels:
root@x1:~# uname -a
Linux x1 6.17.4-200.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sun Oct 19 18:47:49 UTC 2025 x86_64 GNU/Linux
root@x1:~#
root@x1:~# perf test 1
1: vmlinux symtab matches kallsyms : FAILED!
root@x1:~#
Related to:
root@x1:~# grep ' 1 ' /proc/kallsyms
ffffffffb098bc00 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
ffffffffb098bc10 1 _RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
root@x1:~#
That is found in:
root@x1:~# pahole --running_kernel_vmlinux
/usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux
root@x1:~#
root@x1:~# readelf -sW /usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux | grep __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
150649: ffffffff81f8bc00 16 FUNC LOCAL DEFAULT 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
root@x1:~#
But was being filtered out when reading /proc/kallsyms, as the '1'
symbol type was not being handled, do it, there are just two of them at
this point.
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Benno Lossin <lossin@kernel.org>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This change adds a new WQ_PERCPU flag to explicitly request
alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
[ rjw: Subject adjustment ]
Link: https://patch.msgid.link/20251030154739.262582-6-marco.crivellari@suse.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This change adds a new WQ_PERCPU flag to explicitly request
alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
[ rjw: Subject adjustment ]
Link: https://patch.msgid.link/20251030154739.262582-5-marco.crivellari@suse.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This change adds a new WQ_PERCPU flag to explicitly request
alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
[ rjw: Subject adjustment ]
Link: https://patch.msgid.link/20251030154739.262582-4-marco.crivellari@suse.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistency cannot be addressed without refactoring the API.
system_wq should be the per-cpu workqueue, yet in this name nothing makes
that clear, so replace system_wq with system_percpu_wq.
The old wq (system_wq) will be kept for a few release cycles.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20251030154739.262582-3-marco.crivellari@suse.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistency cannot be addressed without refactoring the API.
system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.
Adding system_dfl_wq to encourage its use when unbound work should be used.
The old system_unbound_wq will be kept for a few release cycles.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20251030154739.262582-2-marco.crivellari@suse.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Clarify that the return values of vsprintf() and sprintf() exclude the
trailing NUL character.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20251103090913.2066-2-thorsten.blum@linux.dev
Signed-off-by: Petr Mladek <pmladek@suse.com>
MSG_OP_CHAIN_EXEC_NPU is a unified mailbox message that replaces
MSG_OP_CHAIN_EXEC_BUFFER_CF and MSG_OP_CHAIN_EXEC_DPU.
Add driver logic to check firmware version, and if MSG_OP_CHAIN_EXEC_NPU
is supported, uses it to submit firmware commands.
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20251031014700.2919349-1-lizhi.hou@amd.com
Rename the arm64 sha3_update() function to have an "arm64_" prefix to
avoid a name conflict with the upcoming SHA-3 library.
Note: this code will be superseded later. This commit simply keeps the
kernel building for the initial introduction of the library.
[EB: dropped unnecessary rename of sha3_finup(), and improved commit
message]
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251026055032.1413733-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Rename the s390 sha3_*_init() functions to have an "s390_" prefix to
avoid a name conflict with the upcoming SHA-3 library functions.
Note: this code will be superseded later. This commit simply keeps the
kernel building for the initial introduction of the library.
[EB: dropped unnecessary rename of import and export functions, and
improved commit message]
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251026055032.1413733-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Update aes_gcm_dec_final_vaes_avx2() to be consistent with
aes_gcm_dec_final_aesni() and aes_gcm_dec_final_vaes_avx512() by
initializing the full %rax return register instead of just %al.
Technically this is unnecessary, since these functions return bool. But
I think it's worth being extra careful with the result of the tag
comparison and also keeping the different implementations consistent.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251102015256.171536-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Revert commit 690de2902d ("i2c: muxes: pca954x: Use reset controller
only") and its dependent commit 94c2967764 ("i2c: muxes: pca954x:
Reset if (de)select fails") because the first breaks all users of the
driver, by requiring a completely optional reset-gpio driver. These
commits cause that mux driver simply stops working when optional
reset-gpio is not included, but that reset-gpio is not pulled anyhow.
Driver cannot remove legacy reset-gpios handling.
Fixes: 690de2902d ("i2c: muxes: pca954x: Use reset controller only")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Christian Brauner <brauner@kernel.org> says:
As announced a while ago this is the next step building on the nstree
work from prior cycles. There's a bunch of fixes and semantic cleanups
in here and a ton of tests.
Currently listns() is relying on active namespace reference counts which
are introduced alongside this series.
While a namespace is on the namespace trees with a valid reference count
it is possible to reopen it through a namespace file handle. This is all
fine but has some issues that should be addressed.
On current kernels a namespace is visible to userspace in the
following cases:
(1) The namespace is in use by a task.
(2) The namespace is persisted through a VFS object (namespace file
descriptor or bind-mount).
Note that (2) only cares about direct persistence of the namespace
itself not indirectly via e.g., file->f_cred file references or
similar.
(3) The namespace is a hierarchical namespace type and is the parent of
a single or multiple child namespaces.
Case (3) is interesting because it is possible that a parent namespace
might not fulfill any of (1) or (2), i.e., is invisible to userspace but
it may still be resurrected through the NS_GET_PARENT ioctl().
Currently namespace file handles allow much broader access to namespaces
than what is currently possible via (1)-(3). The reason is that
namespaces may remain pinned for completely internal reasons yet are
inaccessible to userspace.
For example, a user namespace my remain pinned by get_cred() calls to
stash the opener's credentials into file->f_cred. As it stands file
handles allow to resurrect such a users namespace even though this
should not be possible via (1)-(3). This is a fundamental uapi change
that we shouldn't do if we don't have to.
Consider the following insane case: Various architectures support the
CONFIG_MMU_LAZY_TLB_REFCOUNT option which uses lazy TLB destruction.
When this option is set a userspace task's struct mm_struct may be used
for kernel threads such as the idle task and will only be destroyed once
the cpu's runqueue switches back to another task. But because of ptrace()
permission checks struct mm_struct stashes the user namespace of the
task that struct mm_struct originally belonged to. The kernel thread
will take a reference on the struct mm_struct and thus pin it.
So on an idle system user namespaces can be persisted for arbitrary
amounts of time which also means that they can be resurrected using
namespace file handles. That makes no sense whatsoever. The problem is
of course excarabted on large systems with a huge number of cpus.
To handle this nicely we introduce an active reference count which
tracks (1)-(3). This is easy to do as all of these things are already
managed centrally. Only (1)-(3) will count towards the active reference
count and only namespaces which are active may be opened via namespace
file handles.
The problem is that namespaces may be resurrected. Which means that they
can become temporarily inactive and will be reactived some time later.
Currently the only example of this is the SIOGCSKNS socket ioctl. The
SIOCGSKNS ioctl allows to open a network namespace file descriptor based
on a socket file descriptor.
If a socket is tied to a network namespace that subsequently becomes
inactive but that socket is persisted by another process in another
network namespace (e.g., via SCM_RIGHTS of pidfd_getfd()) then the
SIOCGSKNS ioctl will resurrect this network namespace.
So calls to open_related_ns() and open_namespace() will end up
resurrecting the corresponding namespace tree.
Note that the active reference count does not regulate the lifetime of
the namespace itself. This is still done by the normal reference count.
The active reference count can only be elevated if the regular reference
count is elevated.
The active reference count also doesn't regulate the presence of a
namespace on the namespace trees. It only regulates its visiblity to
namespace file handles (and in later patches to listns()).
A namespace remains on the namespace trees from creation until its
actual destruction. This will allow the kernel to always reach any
namespace trivially and it will also enable subsystems like bpf to walk
the namespace lists on the system for tracing or general introspection
purposes.
Note that different namespaces have different visibility lifetimes on
current kernels. While most namespace are immediately released when the
last task using them exits, the user- and pid namespace are persisted
and thus both remain accessible via /proc/<pid>/ns/<ns_type>.
The user namespace lifetime is aliged with struct cred and is only
released through exit_creds(). However, it becomes inaccessible to
userspace once the last task using it is reaped, i.e., when
release_task() is called and all proc entries are flushed. Similarly,
the pid namespace is also visible until the last task using it has been
reaped and the associated pid numbers are freed.
The active reference counts of the user- and pid namespace are
decremented once the task is reaped.
Based on the namespace trees and the active reference count, a new
listns() system call that allows userspace to iterate through namespaces
in the system. This provides a programmatic interface to discover and
inspect namespaces, enhancing existing namespace apis.
Currently, there is no direct way for userspace to enumerate namespaces
in the system. Applications must resort to scanning /proc/<pid>/ns/
across all processes, which is:
1. Inefficient - requires iterating over all processes
2. Incomplete - misses inactive namespaces that aren't attached to any
running process but are kept alive by file descriptors, bind mounts,
or parent namespace references
3. Permission-heavy - requires access to /proc for many processes
4. No ordering or ownership.
5. No filtering per namespace type: Must always iterate and check all
namespaces.
The list goes on. The listns() system call solves these problems by
providing direct kernel-level enumeration of namespaces. It is similar
to listmount() but obviously tailored to namespaces.
/*
* @req: Pointer to struct ns_id_req specifying search parameters
* @ns_ids: User buffer to receive namespace IDs
* @nr_ns_ids: Size of ns_ids buffer (maximum number of IDs to return)
* @flags: Reserved for future use (must be 0)
*/
ssize_t listns(const struct ns_id_req *req, u64 *ns_ids,
size_t nr_ns_ids, unsigned int flags);
Returns:
- On success: Number of namespace IDs written to ns_ids
- On error: Negative error code
/*
* @size: Structure size
* @ns_id: Starting point for iteration; use 0 for first call, then
* use the last returned ID for subsequent calls to paginate
* @ns_type: Bitmask of namespace types to include (from enum ns_type):
* 0: Return all namespace types
* MNT_NS: Mount namespaces
* NET_NS: Network namespaces
* USER_NS: User namespaces
* etc. Can be OR'd together
* @user_ns_id: Filter results to namespaces owned by this user namespace:
* 0: Return all namespaces (subject to permission checks)
* LISTNS_CURRENT_USER: Namespaces owned by caller's user namespace
* Other value: Namespaces owned by the specified user namespace ID
*/
struct ns_id_req {
__u32 size; /* sizeof(struct ns_id_req) */
__u32 spare; /* Reserved, must be 0 */
__u64 ns_id; /* Last seen namespace ID (for pagination) */
__u32 ns_type; /* Filter by namespace type(s) */
__u32 spare2; /* Reserved, must be 0 */
__u64 user_ns_id; /* Filter by owning user namespace */
};
Example 1: List all namespaces
void list_all_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0, /* Start from beginning */
.ns_type = 0, /* All types */
.user_ns_id = 0, /* All user namespaces */
};
uint64_t ids[100];
ssize_t ret;
printf("All namespaces in the system:\n");
do {
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
break;
}
for (ssize_t i = 0; i < ret; i++)
printf(" Namespace ID: %llu\n", (unsigned long long)ids[i]);
/* Continue from last seen ID */
if (ret > 0)
req.ns_id = ids[ret - 1];
} while (ret == 100); /* Buffer was full, more may exist */
}
Example 2 : List network namespaces only
void list_network_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = NET_NS, /* Only network namespaces */
.user_ns_id = 0,
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
return;
}
printf("Network namespaces: %zd found\n", ret);
for (ssize_t i = 0; i < ret; i++)
printf(" netns ID: %llu\n", (unsigned long long)ids[i]);
}
Example 3 : List namespaces owned by current user namespace
void list_owned_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = 0, /* All types */
.user_ns_id = LISTNS_CURRENT_USER, /* Current userns */
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
return;
}
printf("Namespaces owned by my user namespace: %zd\n", ret);
for (ssize_t i = 0; i < ret; i++)
printf(" ns ID: %llu\n", (unsigned long long)ids[i]);
}
Example 4 : List multiple namespace types
void list_network_and_mount_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = NET_NS | MNT_NS, /* Network and mount */
.user_ns_id = 0,
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
printf("Network and mount namespaces: %zd found\n", ret);
}
Example 5 : Pagination through large namespace sets
void list_all_with_pagination(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = 0,
.user_ns_id = 0,
};
uint64_t ids[50];
size_t total = 0;
ssize_t ret;
printf("Enumerating all namespaces with pagination:\n");
while (1) {
ret = listns(&req, ids, 50, 0);
if (ret < 0) {
perror("listns");
break;
}
if (ret == 0)
break; /* No more namespaces */
total += ret;
printf(" Batch: %zd namespaces\n", ret);
/* Last ID in this batch becomes start of next batch */
req.ns_id = ids[ret - 1];
if (ret < 50)
break; /* Partial batch = end of results */
}
printf("Total: %zu namespaces\n", total);
}
listns() respects namespace isolation and capabilities:
(1) Global listing (user_ns_id = 0):
- Requires CAP_SYS_ADMIN in the namespace's owning user namespace
- OR the namespace must be in the caller's namespace context (e.g.,
a namespace the caller is currently using)
- User namespaces additionally allow listing if the caller has
CAP_SYS_ADMIN in that user namespace itself
(2) Owner-filtered listing (user_ns_id != 0):
- Requires CAP_SYS_ADMIN in the specified owner user namespace
- OR the namespace must be in the caller's namespace context
- This allows unprivileged processes to enumerate namespaces they own
(3) Visibility:
- Only "active" namespaces are listed
- A namespace is active if it has a non-zero __ns_ref_active count
- This includes namespaces used by running processes, held by open
file descriptors, or kept active by bind mounts
- Inactive namespaces (kept alive only by internal kernel
references) are not visible via listns()
* patches from https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org: (74 commits)
selftests/namespace: test listns() pagination
selftests/namespace: add stress test
selftests/namespace: commit_creds() active reference tests
selftests/namespace: third threaded active reference count test
selftests/namespace: second threaded active reference count test
selftests/namespace: first threaded active reference count test
selftests/namespaces: twelth inactive namespace resurrection test
selftests/namespaces: eleventh inactive namespace resurrection test
selftests/namespaces: tenth inactive namespace resurrection test
selftests/namespaces: ninth inactive namespace resurrection test
selftests/namespaces: eigth inactive namespace resurrection test
selftests/namespaces: seventh inactive namespace resurrection test
selftests/namespaces: sixth inactive namespace resurrection test
selftests/namespaces: fifth inactive namespace resurrection test
selftests/namespaces: fourth inactive namespace resurrection test
selftests/namespaces: third inactive namespace resurrection test
selftests/namespaces: second inactive namespace resurrection test
selftests/namespaces: first inactive namespace resurrection test
selftests/namespaces: seventh listns() permission test
selftests/namespaces: sixth listns() permission test
...
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stress tests for namespace active reference counting.
These tests validate that the active reference counting system can
handle high load scenarios including rapid namespace
creation/destruction, large numbers of concurrent namespaces, and
various edge cases under stress.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-71-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test that namespaces become inactive after subprocess with multiple
threads exits. Create a subprocess that unshares user and network
namespaces, then creates two threads that share those namespaces. Verify
that after all threads and subprocess exit, the namespaces are no longer
listed by listns() and cannot be opened by open_by_handle_at().
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-69-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test that a namespace remains active while a thread holds an fd to it.
Even after the thread exits, the namespace should remain active as long
as another thread holds a file descriptor to it.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-68-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test multi-level namespace resurrection across three user namespace levels.
This test creates a complex namespace hierarchy with three levels of user
namespaces and a network namespace at the deepest level. It verifies that
the resurrection semantics work correctly when SIOCGSKNS is called on a
socket from an inactive namespace tree, and that listns() and
open_by_handle_at() correctly respect visibility rules.
Hierarchy after child processes exit (all with 0 active refcount):
net_L3A (0) <- Level 3 network namespace
|
+
userns_L3 (0) <- Level 3 user namespace
|
+
userns_L2 (0) <- Level 2 user namespace
|
+
userns_L1 (0) <- Level 1 user namespace
|
x
init_user_ns
The test verifies:
1. SIOCGSKNS on a socket from inactive net_L3A resurrects the entire chain
2. After resurrection, all namespaces are visible in listns()
3. Resurrected namespaces can be reopened via file handles
4. Closing the netns FD cascades down: the entire ownership chain
(userns_L3 -> userns_L2 -> userns_L1) becomes inactive again
5. Inactive namespaces disappear from listns() and cannot be reopened
6. Calling SIOCGSKNS again on the same socket resurrects the tree again
7. After second resurrection, namespaces are visible and can be reopened
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-66-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test combined listns() and file handle operations with socket-kept
netns. Create a netns, keep it alive with a socket, verify it appears in
listns(), then reopen it via file handle obtained from listns() entry.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-65-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test that socket-kept netns can be reopened via file handle.
Verify that a network namespace kept alive by a socket FD can be
reopened using file handles even after the creating process exits.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-64-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Test that socket-kept netns appears in listns() output.
Verify that a network namespace kept alive by a socket FD appears in
listns() output even after the creating process exits, and that it
disappears when the socket is closed.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-63-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
