linux-kernel - [PATCH v2 5/5] selftests/futex: fix the issue of abnormal test results caused by thread timing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <tencent_14CA2C6995E7C11795D4F60E656AD9422C06@qq.com>
Date: Tue, 16 Dec 2025 17:19:02 +0800
From: Licay <licayy@...mail.com>
To: ywen.chen@...mail.com,
	akpm@...ux-foundation.org
Cc: andrealmeid@...lia.com,
	bigeasy@...utronix.de,
	colin.i.king@...il.com,
	dave@...olabs.net,
	dvhart@...radead.org,
	justinstitt@...gle.com,
	kernel-team@...roid.com,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	luto@....edu,
	mingo@...hat.com,
	morbo@...gle.com,
	nathan@...nel.org,
	ndesaulniers@...gle.com,
	peterz@...radead.org,
	shuah@...nel.org,
	tglx@...utronix.de,
	usama.anjum@...labora.com,
	Licay <licayy@...mail.com>
Subject: [PATCH v2 5/5] selftests/futex: fix the issue of abnormal test results caused by thread timing

> Fixes a race between parent and child threads in futex_requeue.
>
> Similar to commit fbf4dec70277 ("selftests/futex: Order calls to
> futex_lock_pi"), which fixed a flake in futex_lock_pi due to racing
> between the parent and child threads.
>
> The same issue can occur in the futex_requeue test, because it expects
> waiterfn to make progress to futex_wait before the parent starts to
> requeue. This is mitigated by the parent sleeping for WAKE_WAIT_US, but
> it still fails occasionally. This can be reproduced by adding a sleep in
> the waiterfn before futex_wait:
>
> TAP version 13
> 1..2
> not ok 1 futex_requeue simple returned: 0
> not ok 2 futex_requeue simple returned: 0
> not ok 3 futex_requeue many returned: 0
> not ok 4 futex_requeue many returned: 0
>
> This issue can be resolved by checking whether the child thread is in a
> sleeping state. This is because when the child thread goes to sleep, it
> indicates that it is waiting for the futex lock.
>
> Fixes: 7cb5dd8e2c8c ("selftests: futex: Add futex compare requeue test")
> Signed-off-by: Yuwen Chen <ywen.chen@...mail.com>
> Co-developed-by: Edward Liaw <edliaw@...gle.com>
> Signed-off-by: Edward Liaw <edliaw@...gle.com>
> ---
>  .../futex/functional/futex_requeue.c          | 58 ++++++++++++++++---
>  1 file changed, 51 insertions(+), 7 deletions(-)
Reviewed-by: Licay <licayy@...mail.com>