I don't know if this is worth reporting - please let me know what your thoughts are on the following email. Recipients are from 'get_maintainer.pl -f tools/testing/selftests/x86/fsgsbase.c'.
--- To: Shuah Khan shuah@kernel.org, Ingo Molnar mingo@kernel.org, Andy Lutomirski luto@kernel.org, Dmitry Safonov dsafonov@virtuozzo.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: selftests/x86/fsgsbase_64 test problem
We've noticed that fsgsbase_64 can fail periodically with the following error:
[RUN] ARCH_SET_GS(0x0) and clear gs, then schedule to 0x1 Before schedule, set selector to 0x1 other thread: ARCH_SET_GS(0x1) -- sel is 0x0 [FAIL] GS/BASE changed from 0x1/0x0 to 0x0/0x0
This can be reliably reproduced by running fsgsbase_64 in a loop. i.e.
for i in $(seq 1 10000); do ./fsgsbase_64 || break; done
This problem isn't new - I've reproduced it on latest mainline and every release going back to v4.12 (I did not try earlier).
Thanks, Dan
On 24 January 2018 at 20:08, Dan Rue dan.rue@linaro.org wrote:
I don't know if this is worth reporting - please let me know what your thoughts are on the following email. Recipients are from 'get_maintainer.pl -f tools/testing/selftests/x86/fsgsbase.c'.
To: Shuah Khan shuah@kernel.org, Ingo Molnar mingo@kernel.org, Andy Lutomirski luto@kernel.org, Dmitry Safonov dsafonov@virtuozzo.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: selftests/x86/fsgsbase_64 test problem
I might also include Boris Petkov who reviewed at least the initial change adding the test.
We've noticed that fsgsbase_64 can fail periodically with the following error:
Periodically or intermittently?
[RUN] ARCH_SET_GS(0x0) and clear gs, then schedule to 0x1 Before schedule, set selector to 0x1 other thread: ARCH_SET_GS(0x1) -- sel is 0x0 [FAIL] GS/BASE changed from 0x1/0x0 to 0x0/0x0This can be reliably reproduced by running fsgsbase_64 in a loop. i.e.
for i in $(seq 1 10000); do ./fsgsbase_64 || break; doneThis problem isn't new - I've reproduced it on latest mainline and every release going back to v4.12 (I did not try earlier).
Possibly worth mentioning what sort of systems you're using in case they're unusual ones for that feature.
Thanks, Dan
On Thu, Jan 25, 2018 at 11:51:32AM +0000, Mark Brown wrote:
On 24 January 2018 at 20:08, Dan Rue <[1]dan.rue@linaro.org> wrote:
I don't know if this is worth reporting - please let me know what your thoughts are on the following email. Recipients are from '[2]get_maintainer.pl -f tools/testing/selftests/x86/fsgsbase.c'. --- To: Shuah Khan <[3]shuah@kernel.org>, Ingo Molnar <[4]mingo@kernel.org>, Andy Lutomirski <[5]luto@kernel.org>, Dmitry Safonov <[6]dsafonov@virtuozzo.com>, [7]linux-kselftest@vger.kernel.org, [8]linux-kernel@vger.kernel.org Subject: selftests/x86/fsgsbase_64 test problemI might also include Boris Petkov who reviewed at least the initial change adding the test.
We've noticed that fsgsbase_64 can fail periodically with the following error:Periodically or intermittently?
[RUN] ARCH_SET_GS(0x0) and clear gs, then schedule to 0x1 Before schedule, set selector to 0x1 other thread: ARCH_SET_GS(0x1) -- sel is 0x0 [FAIL] GS/BASE changed from 0x1/0x0 to 0x0/0x0 This can be reliably reproduced by running fsgsbase_64 in a loop. i.e. for i in $(seq 1 10000); do ./fsgsbase_64 || break; done This problem isn't new - I've reproduced it on latest mainline and every release going back to v4.12 (I did not try earlier).Possibly worth mentioning what sort of systems you're using in case they're unusual ones for that feature.
Thanks for the review Mark. Email sent with your suggestions made.
Dan
-
Dan Rue -
Mark Brown