linux.git/tools/testing/selftests/pid_namespace, branch v7.2-rc2

selftests/pid_namespace: compute pid_max test limits dynamically

2026-05-11T09:09:30+00:00

The pid_max kselftest hardcodes pid_max values of 400 and 500, but the
kernel enforces a minimum of PIDS_PER_CPU_MIN * num_possible_cpus().
On machines with many possible CPUs (e.g. nr_cpu_ids=128 yields a
minimum of 1024), writing 400 or 500 to /proc/sys/kernel/pid_max
returns EINVAL and all three tests fail.

Compute these limits the same way as the kernel does and set outer_limit
and inner_limit dynamically based on the result. Original test semantics
are preserved (outer < inner, nested namespace capped by parent).

Signed-off-by: Bjoern Doebel 
Link: https://patch.msgid.link/20260422201151.3830506-1-doebel@amazon.com
Reviewed-by: Pavel Tikhomirov 
Assisted-by: Kiro:claude-opus-4.6
Signed-off-by: Christian Brauner

selftests: Add tests for creating pidns init via setns

2026-03-20T13:44:26+00:00

First testcase "pidns_init_via_setns" checks that a process can become
Pid 1 (init) in a new Pid namespace created via unshare() and joined via
setns().

Second testcase "pidns_init_via_setns_set_tid" checks that during this
process we can use clone3() + set_tid and set the pid in both the new
and old pid namespaces (owned by different user namespaces). This test
requires root to run to avoid complex setup for wrapper userns.

Signed-off-by: Pavel Tikhomirov 

--
pidns_init_via_setns. Make pidns_init_via_setns_set_tid require root.

Link: https://patch.msgid.link/20260318122157.280595-5-ptikhomirov@virtuozzo.com
v6: Move wrapper userns creation for unprivileged case to the top of
Signed-off-by: Christian Brauner

selftests: complete kselftest include centralization

2025-11-27T22:24:31+00:00

This follow-up patch completes centralization of kselftest.h and
ksefltest_harness.h includes in remaining seltests files, replacing all
relative paths with a non-relative paths using shared -I include path in
lib.mk

Tested with gcc-13.3 and clang-18.1, and cross-compiled successfully on
riscv, arm64, x86_64 and powerpc arch.

[reddybalavignesh9979@gmail.com: add selftests include path for kselftest.h]
  Link: https://lkml.kernel.org/r/20251017090201.317521-1-reddybalavignesh9979@gmail.com
Link: https://lkml.kernel.org/r/20251016104409.68985-1-reddybalavignesh9979@gmail.com
Signed-off-by: Bala-Vignesh-Reddy 
Suggested-by: Andrew Morton 
Link: https://lore.kernel.org/lkml/20250820143954.33d95635e504e94df01930d0@linux-foundation.org/
Reviewed-by: Wei Yang 
Cc: David Hildenbrand 
Cc: David S. Miller 
Cc: Eric Dumazet 
Cc: Günther Noack 
Cc: Jakub Kacinski 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Michal Hocko 
Cc: Mickael Salaun 
Cc: Ming Lei 
Cc: Paolo Abeni 
Cc: Shuah Khan 
Cc: Simon Horman 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

selftests: pid_namespace: add missing sys/mount.h include in pid_max.c

2025-05-09T19:12:33+00:00

Fix compile on openSUSE Tumbleweed (gcc-14.2.1, glibc-2.40):
  - add missing sys/mount.h include

Fixes:

  pid_max.c: In function ‘pid_max_cb’:
  pid_max.c:42:15: error: implicit declaration of function ‘mount’ [-Wimplicit-function-declaration]
     42 |         ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        |               ^~~~~

Link: https://lore.kernel.org/r/20250115105211.390370-3-ps.report@gmx.net
Signed-off-by: Peter Seiderer 
Reviewed-by: T.J. Mercier 
Signed-off-by: Shuah Khan

tests/pid_namespace: add pid_max tests

2024-12-02T10:25:25+00:00

Signed-off-by: Alexander Mikhalitsyn 
Link: https://lore.kernel.org/r/20241122132459.135120-3-aleksandr.mikhalitsyn@canonical.com
Signed-off-by: Christian Brauner

selftests: pid_namespace: Fix incorrect kernel headers search path

2023-02-13T16:09:45+00:00

Use $(KHDR_INCLUDES) as lookup path for kernel headers. This prevents
building against kernel headers from the build environment in scenarios
where kernel headers are installed into a specific output directory
(O=...).

Signed-off-by: Mathieu Desnoyers 
Cc: Shuah Khan 
Cc: linux-kselftest@vger.kernel.org
Cc: Ingo Molnar 
Cc:   # 5.18+
Signed-off-by: Shuah Khan

selftests: fix header dependency for pid_namespace selftests

2022-04-04T19:32:31+00:00

The way the test target was defined before, when building with clang we
get a command line like this:

clang -Wall -Werror -g -I../../../../usr/include/ \
	regression_enomem.c ../pidfd/pidfd.h  -o regression_enomem

This yields an error, because clang thinks we want to produce both a *.o
file, as well as a precompiled header:

clang: error: cannot specify -o when generating multiple output files

gcc, for whatever reason, doesn't exhibit the same behavior which I
suspect is why the problem wasn't noticed before.

This can be fixed simply by using the LOCAL_HDRS infrastructure the
selftests lib.mk provides. It does the right think and marks the target
as depending on the header (so if the header changes, we rebuild), but
it filters the header out of the compiler command line, so we don't get
the error described above.

Signed-off-by: Axel Rasmussen 
Reviewed-by: Christian Brauner 
Signed-off-by: Shuah Khan

selftests: Remove unneeded selftest API headers

2020-07-06T21:59:07+00:00

Remove unused includes of the kselftest.h header.

Acked-by: Christian Brauner 
Signed-off-by: Kees Cook 
Signed-off-by: Shuah Khan

selftests: add pid namespace ENOMEM regression test

2020-03-25T12:50:34+00:00

We recently regressed (cf. [1] and its corresponding fix in [2]) returning
ENOMEM when trying to create a process in a pid namespace whose init
process/child subreaper has already died. This has caused confusion at
least once before that (cf. [3]). Let's add a simple regression test to
catch this in the future.

[1]: 49cb2fc42ce4 ("fork: extend clone3() to support setting a PID")
[2]: b26ebfe12f34 ("pid: Fix error return value in some cases")
[3]: 35f71bc0a09a ("fork: report pid reservation failure properly")
Cc: Corey Minyard 
Cc: Oleg Nesterov 
Cc: Adrian Reber 
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Andrei Vagin 
Signed-off-by: Christian Brauner