I notice a random freeze every 5~10 boots with kernel 3.17.1 ( and 3.17.2 ) with systemd 216-3 and also systemd 217-3,


every 5~10 boots a freeze can occur shortly after the load of the kernel, I can see these messages on screen and then nothing, it seems like a freeze :

:: running early hook [udev]
:: running hook [udev]
:: Triggering uvents...

sometimes the freeze happens a few seconds after systemd starts ( after the message "mount /home" for example ),

after 5 minutes of inactivity systemd shows this message :

task systemd-udevd:236 blocked for more than 120 seconds

and I have to do a RESET in order to have a correct boot, because systemd is unable to finish the boot of the PC,

my configuration :
archlinux 64 bits
cpu pentium dual core E6800 3.33 Ghz
ati radeon HD4650 PCIe

Created attachment 108819 [details]
the kernel call trace when a freeze occurs at boot

the kernel call trace when a freeze occurs at boot

Created attachment 108820 [details]
dmesg when no freeze occurs

dmesg when no freeze occurs

almost certainly a kernel problem, if the kernel stays hanging there.

It sounds like a race with a kernel driver/module loading. It is very
unlikely that udev can anything about it to fix it, at least I have no
idea where to look for.

You could try to blacklist kernel modules, to prevent them from being
loaded. The list of modules show up in "lsmod" at a successful boot, and
you could add some of them (things which are not needed to bring up the
machine) to a modprobe config file and blacklist them.

If you happen to have more information and think that userspace causes this,
please reopen.

yes it's a kernel problem,

I'm sure now because after investigations I found the guilty, it's the commit 74665016086615bbaa3fa6f83af410a0a4e029ee "( scsi: convert
host_busy to atomic_t )" who has introduced the bug,

the bug is triggered if a slow sata/ide device ( like a DVD burner ) is mixed with a sata/ide hardisk AND if the motherboard or the sata/ide controler doesn't support AHCI, a random hang will occur every 5~10 boots, systemd will stop and some error messages will be displayed because sata/ide devices suddenly stop :


https://lkml.org/lkml/2014/11/19/634

a patch is available :

https://bugzilla.kernel.org/attachment.cgi?id=158411

but I don't know if linux developpers will use this patch for kernel 3.18,

it's a nasty bug and some people are not aware about this bug ( bug introduced with kernel 3.17 ), but they will likely have this bug if they mix slow SATA/IDE devices with fast devices on a sata/ide controler who doesn't support AHCI

the bug report :

https://bugzilla.kernel.org/show_bug.cgi?id=87581