Hi, thanks for the datapoint! If debugging doesn't lead to any result, I will try with your version to see if that fixes it for us.
I should also try our version with your patch to fix the compilation instead of the one we are using currently. Maybe that just happens to fix the issue. Thanks for offering to share the kernel. However, we also have a bunch of (hopefully) unrelated changes we need on our system, so its probably better if we build it ourselves. Don't worry about your English. Best, Nikolaus -----Original Message----- From: Daniel Vidal [mailto:danielvidalchor...@gmail.com] Sent: Montag, 16. Januar 2017 20:16 To: Demmel Nikolaus (BOSP/PAR) <nikolaus.dem...@de.bosch.com> Cc: aufs-users@lists.sourceforge.net Subject: Re: AUFS and PREEMPT_RT boot issue Hi Now, i continue appliyng my patch to compile KERNEL+RT+AUFS. I was try to use the rt_mutex_set_owner() wihtout success. I do not remember what the problem was. Now i'm running 4.4.38-rt49 Kernel wiht RT and AUFS Linux x64-v3 4.4.38-rt49 #1 SMP PREEMPT RT Mon Dec 19 10:28:46 CET 2016 x86_64 GNU/Linux I use the kernel to run a DEBIAN based live system. If you want test my kernel i can share-it on google drive. Sorry for my english. 2017-01-16 16:57 GMT+01:00 Demmel Nikolaus (BOSP/PAR) <nikolaus.dem...@de.bosch.com>: > Hi J. R. Okajima, > > thank you for your prompt response. > > I'm assuming from your response that in general you expect AUFS to work with > PREEMPT_RT, or is this not the case? > > "Demmel Nikolaus (BOSP/PAR)": >> > we are using AUFS for our root filesystem with an tmpfs overlay and >> > recentl= >> > y wanted to switch to a kernel with PREEMPT_RT patch. Unfortunately, it >> > see= >> > ms that mounting aufs seems to hang about 40% of the time during boot >> > (ther= >> > e is no specific kernel or log message). When it comes up, it seems to >> > work= >> > correctly. > >> Do you mean that mounting aufs took very long time and your system runs >> flawlessly after that? >> Interesting... > >> My first suggestion to see what is going on is "strace -T -f mount -t aufs >> ..." >> which will give us a hint. > >> Sometimes people sets aufs FHSM feature incorrectly. That >> setting/configuration should match in kernel-space and user-space. If it >> doesn't match, it will take a long time in mounting aufs unexpectedly. >> When FHSM is enabled both in kernel and user-space, then it will take a >> long time too. But it is an expected behaviour. > > What I actually mean is that in about 40% of the time when booting into a > kernel with the RT patch, the boot hangs at > > mount -t aufs -o "dirs=/rw=rw:/ro=ro" aufs $ROOT_MOUNT > > in our init script and does not appear to return at all. The other 60% it > works as expected without delay. > > Then exact same configuration just without PREEMPT_RT patch appears to work > 100% of the time. > > Does your answer still apply? Should we try the strace? > >> > In order to get AUFS to compile, we needed to apply the following >> > additiona= >> > l patch: >> > https://github.com/beagleboard/linux/pull/108/commits/ad740435f28e= >> > 3ffb5d73a419086b0b6fd3bc7240 > >> Hmm, this patch reminds me a post from Daniel Vidal in May 2013 (the >> patch looks different from what I suggested, though). Refer to >> http://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg04210.html >> and its thread. > > Hm... interesting. To me (being unfamiliar with the innards of both > PREEMPT_RT and AUFS) this > looks like potential for a locking issue. The patch / discussion you linked > seems to suggest that > the owner should be set assigned to lock.owner, which is not done in the > patch we are using. Mind that > the patch I linked is also just something I stumbled across while googling > the initial compile error. > In particular the commit message doesn't sound too confident that the change > is actually the correct > fix and not just a way to make it compile. > > Do you suggest that we should try to change it to the patch you linked? > >> Next time when you post, tell me the version of patches you are using >> and the URL where I can get all of thme. > > Sorry, here are the versions, I hope this helps (I'm copying this from a > yocto build config and I'm not sure in what format it would be most useful > for you. I'm not even sure what would be the best tool to use to get from the > list of repos with kernel source and patches a compiled kernel without using > yocto). > > https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.1.30.tar.xz > http://git.linuxfoundation.org/?p=ltsi-kernel.git;a=commit;h=079621627b2d96cf0d85a0413ce5670056a70751w > https://github.com/sfjro/aufs4-standalone.git > https://www.kernel.org/pub/linux/kernel/projects/rt/4.1/older/patches-4.1.30-rt34.tar.xz > > Best, > Nikolaus > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot
