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Axel Rasmussen fc6d187f29 pidfd: fix test failure due to stack overflow on some arches
[ Upstream commit 4cbd93c3c1 ]

When running the pidfd_fdinfo_test on arm64, it fails for me. After some
digging, the reason is that the child exits due to SIGBUS, because it
overflows the 1024 byte stack we've reserved for it.

To fix the issue, increase the stack size to 8192 bytes (this number is
somewhat arbitrary, and was arrived at through experimentation -- I kept
doubling until the failure no longer occurred).

Also, let's make the issue easier to debug. wait_for_pid() returns an
ambiguous value: it may return -1 in all of these cases:

1. waitpid() itself returned -1
2. waitpid() returned success, but we found !WIFEXITED(status).
3. The child process exited, but it did so with a -1 exit code.

There's no way for the caller to tell the difference. So, at least log
which occurred, so the test runner can debug things.

While debugging this, I found that we had !WIFEXITED(), because the
child exited due to a signal. This seems like a reasonably common case,
so also print out whether or not we have WIFSIGNALED(), and the
associated WTERMSIG() (if any). This lets us see the SIGBUS I'm fixing
clearly when it occurs.

Finally, I'm suspicious of allocating the child's stack on our stack.
man clone(2) suggests that the correct way to do this is with mmap(),
and in particular by setting MAP_STACK. So, switch to doing it that way
instead.

Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-02-23 12:03:18 +01:00
arch arm64: dts: meson-g12: drop BL32 region from SEI510/SEI610 2022-02-23 12:03:18 +01:00
block block: fix surprise removal for drivers calling blk_set_queue_dying 2022-02-23 12:03:15 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto crypto: api - Move cryptomgr soft dependency into algapi 2022-02-11 09:10:26 +01:00
Documentation ARM: dts: Fix timer regression for beagleboard revision c 2022-02-16 12:56:21 +01:00
drivers irqchip/sifive-plic: Add missing thead,c900-plic match string 2022-02-23 12:03:17 +01:00
fs ksmbd: don't align last entry offset in smb2 query directory 2022-02-23 12:03:18 +01:00
include x86/bug: Merge annotate_reachable() into _BUG_FLAGS() asm 2022-02-23 12:03:17 +01:00
init init: make unknown command line param message clearer 2021-11-18 19:17:11 +01:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-08 18:34:03 +01:00
kernel gcc-plugins/stackleak: Use noinstr in favor of notrace 2022-02-23 12:03:07 +01:00
lib lib/test_meminit: destroy cache in kmem_cache_alloc_bulk() test 2022-01-27 11:05:44 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: don't try to NUMA-migrate COW pages that have other uses 2022-02-23 12:03:03 +01:00
net netfilter: conntrack: don't refresh sctp entries in closed state 2022-02-23 12:03:17 +01:00
samples samples: bpf: Fix 'unknown warning group' build warning on Clang 2022-01-27 11:03:29 +01:00
scripts Makefile.extrawarn: Move -Wunaligned-access to W=1 2022-02-16 12:56:39 +01:00
security ima: Do not print policy rule with inactive LSM labels 2022-02-16 12:56:04 +01:00
sound ASoC: qcom: Actually clear DMA interrupt register for HDMI 2022-02-23 12:03:15 +01:00
tools pidfd: fix test failure due to stack overflow on some arches 2022-02-23 12:03:18 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: eventfd: Fix false positive RCU usage warning 2022-02-16 12:56:16 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15.24 2022-02-16 12:56:41 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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 Restructured Text 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.