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Aristeu Rozanski cf27a5efbb selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT 
[ Upstream commit b24335521d ]

selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT

In order to synchronize new processes to test inheritance of memfd_noexec
sysctl, memfd_test sets up the sysctl with a value before creating the new
process.  The new process then sends itself a SIGSTOP in order to wait for
the parent to flip the sysctl value and send a SIGCONT signal.

This would work as intended if it wasn't the fact that the new process is
being created with CLONE_NEWPID, which creates a new PID namespace and the
new process has PID 1 in this namespace.  There're restrictions on sending
signals to PID 1 and, although it's relaxed for other than root PID
namespace, it's biting us here.  In this specific case the SIGSTOP sent by
the new process is ignored (no error to kill() is returned) and it never
stops its execution.  This is usually not noticiable as the parent usually
manages to set the new sysctl value before the child has a chance to run
and the test succeeds.  But if you run the test in a loop, it eventually
reproduces:

	while [ 1 ]; do ./memfd_test >log 2>&1 || break; done; cat log

So this patch replaces the SIGSTOP/SIGCONT synchronization with IPC
semaphore.

Link: https://lkml.kernel.org/r/a7776389-b3d6-4b18-b438-0b0e3ed1fd3b@work
Fixes: 6469b66e3f ("selftests: improve vm.memfd_noexec sysctl tests")
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: liuye <liuye@kylinos.cn>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-03-04 07:20:35 -05:00
arch arm64: dts: qcom: sm6115: Add CX_MEM/DBGC GPU regions 2026-03-04 07:19:47 -05:00
block block: add a bio_add_virt_nofail helper 2026-03-04 07:19:26 -05:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:28:39 +01:00
Documentation Documentation: tracing: Add PCI tracepoint documentation 2026-03-04 07:19:59 -05:00
drivers powercap: intel_rapl_tpmi: Remove FW_BUG from invalid version check 2026-03-04 07:20:35 -05:00
fs fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot 2026-03-04 07:20:34 -05:00
include clk: Move clk_{save,restore}_context() to COMMON_CLK section 2026-03-04 07:20:27 -05:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring/cancel: de-unionize file and user_data in struct io_cancel_data 2026-03-04 07:20:34 -05:00
ipc ipc: don't audit capability check in ipc_permissions() 2026-03-04 07:20:07 -05:00
kernel tracing: Remove duplicate ENABLE_EVENT_STR and DISABLE_EVENT_STR macros 2026-03-04 07:20:25 -05:00
lib procfs: avoid fetching build ID while holding VMA lock 2026-02-11 13:40:18 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather 2026-02-19 16:29:55 +01:00
net RDMA/core: add rdma_rw_max_sge() helper for SQ sizing 2026-03-04 07:20:22 -05:00
rust rust: rbtree: fix documentation typo in CursorMut peek_next method 2026-02-06 16:55:44 +01:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:14:50 +01:00
scripts scripts: generate_rust_analyzer: Add compiler_builtins -> core dep 2026-02-06 16:55:47 +01:00
security evm: Use ordered xattrs list to calculate HMAC in evm_init_hmac() 2026-03-04 07:19:56 -05:00
sound ASoC: nau8821: Fixup nau8821_enable_jack_detect() 2026-03-04 07:19:52 -05:00
tools selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT 2026-03-04 07:20:35 -05:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: Don't clobber irqfd routing type when deassigning irqfd 2026-02-11 13:40:17 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS gpiolib-acpi: Update file references in the Documentation and MAINTAINERS 2026-02-11 13:40:29 +01:00
Makefile kbuild: Add objtool to top-level clean target 2026-03-04 07:20:35 -05:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.