Hi Thomas, [full quote below] Did you have any time to look into this yet? :) The warning is still reproducible. On Thu, Nov 29, 2018 at 12:23:21PM +0100, Heiko Carstens wrote: > On Wed, Nov 28, 2018 at 03:32:45PM +0100, Thomas Gleixner wrote: > > Heiko, > > > > On Tue, 27 Nov 2018, Heiko Carstens wrote: > > > > > with the glibc self-tests I was able to trigger the "this should not > > > happen" warning ;) below on s390 (with panic_on_warn=1 set). It looks > > > like it is hardly reproducible. > > > > Any idea which self-test triggered that? > > > > > This one happened with commit d146194f31c9 for compiling the kernel. > > > Config can be re-created with "make ARCH=s390 performance_defconfig". > > > > Which is not really helpful for people who do not own a s390. And no, I > > don't want one unless IBM pays the power bill as well :) > > > > > [ 649.596938] WARNING: CPU: 0 PID: 58886 at kernel/futex.c:1418 do_futex+0xa9a/0xc50 > > > [ 649.596946] Kernel panic - not syncing: panic_on_warn set ... > > > [ 649.596951] CPU: 0 PID: 58886 Comm: ld64.so.1 Not tainted 4.20.0-20181125.rc3.git0.d146194f31c9.300.fc29.s390x+git #1 > > > > That's ld64.so.1. Weird, but what do I know about glibc self tests. > > > > I still fail to see how that can happen, but I usually page out the futex > > horrors immediately. I'll keep staring at the code... > > I looked into the system dumps, and if I didn't screw up, then the > command line for both occurrences was > > /root/glibc-build/nptl/tst-robustpi8 > > And indeed, if I run only this test case in an endless loop and do > some parallel work (like kernel compile) it currently seems to be > possible to reproduce the warning: > > while true; do time ./testrun.sh nptl/tst-robustpi8 --direct ; done > > within the build directory of glibc (2.28). > > See > https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/tst-robustpi8.c;h=cbea3d6d77abb00be05ec7b466d8339c26dd2efb;hb=3c03baca37fdcb52c3881e653ca392bba7a99c2b > > which includes this one: > > https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/tst-robust8.c;h=9c636250d4cb0bcd6d802910e8f9ea31568bb73f;hb=3c03baca37fdcb52c3881e653ca392bba7a99c2b >
