11.01.2022 20:20, Eric W. Biederman пишет: > Dmitry Osipenko <digetx@xxxxxxxxx> writes: > >> 08.01.2022 21:13, Eric W. Biederman пишет: >>> Dmitry Osipenko <digetx@xxxxxxxxx> writes: >>> >>>> 05.01.2022 22:58, Eric W. Biederman пишет: >>>>> >>>>> I have not yet been able to figure out how to run gst-pluggin-scanner in >>>>> a way that triggers this yet. In truth I can't figure out how to >>>>> run gst-pluggin-scanner in a useful way. >>>>> >>>>> I am going to set up some unit tests and see if I can reproduce your >>>>> hang another way, but if you could give me some more information on what >>>>> you are doing to trigger this I would appreciate it. >>>> >>>> Thanks, Eric. The distro is Arch Linux, but it's a development >>>> environment where I'm running latest GStreamer from git master. I'll try >>>> to figure out the reproduction steps and get back to you. >>> >>> Thank you. >>> >>> Until I can figure out why this is causing problems I have dropped the >>> following two patches from my queue: >>> signal: Make SIGKILL during coredumps an explicit special case >>> signal: Drop signals received after a fatal signal has been processed >>> >>> I have replaced them with the following two patches that just do what >>> is needed for the rest of the code in the series: >>> signal: Have prepare_signal detect coredumps using >>> signal: Make coredump handling explicit in complete_signal >>> >>> Perversely my failure to change the SIGKILL handling when coredumps are >>> happening proves to me that I need to change the SIGKILL handling when >>> coredumps are happening to make the code more maintainable. >> >> Eric, thank you again. I started to look at the reproduction steps and >> haven't completed it yet. Turned out the problem affects only older >> NVIDIA Tegra2 Cortex-A9 CPU that lacks support of ARM NEON instructions >> set, hence the problem isn't visible on x86 and other CPUs out of the >> box. I'll need to check whether the problem could be simulated on all >> arches or maybe it's specific to VFP exception handling of ARM32. > > It sounds like the gstreamer plugins only fail on certain hardware on > arm32, and things don't hang in coredumps unless the plugins fail. > That does make things tricky to minimize. > > I have just verified that the known problematic code is not > in linux-next for Jan 11 2022. > > If folks as they have time can double check linux-next and verify all is > well I would appreciate it. I don't expect that there are problems but > sometimes one problem hides another. Hello Eric, I reproduced the trouble on x86_64. Here are the reproduction steps, using ArchLinux and linux-next-20211224: ``` sudo pacman -S base-devel git mesa glu meson wget git clone https://github.com/grate-driver/gstreamer.git cd gstreamer git checkout sigill meson --prefix=/usr -Dgst-plugins-base:playback=enabled -Dgst-devtools:validate=disabled build cd build sudo ninja install wget https://www.peach.themazzone.com/big_buck_bunny_720p_h264.mov rm -r ~/.cache/gstreamer-1.0 gst-play-1.0 ./big_buck_bunny_720p_h264.mov ``` The SIGILL, thrown by [1], causes the hang. There is no hang using v5.16.1 kernel. [1] https://github.com/grate-driver/gstreamer/commit/006f9a2ee6dcf7b31c9b5413815d6054d82a3b2f
