Init not handling signals
Hi,
I'm not sure if this is the correct forum to ask this question but I have seen a few buildroot/busybox references to this problem but none with a clear solution.
I am running buildroot-2012-05 with busybox 1.19, using the busybox init with an inittab based on the default one provided.
In the init tab there is a trap for ctrlaltdel
::ctrlaltdel:/sbin/reboot
This line is never called after hitting ctrl alt del on a keyboard
Instead we get a signal pending on the init task
Cat /proc/1/status
---------------------------
Name: swapper
State: R (running)
Tgid: 1
Pid: 1
PPid: 0
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 32
Groups:
Threads: 1
SigQ: 1/938
SigPnd: 0000000000000100
ShdPnd: 0000000000000002
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000000000000
CapInh: 0000000000000000
After the init process is signalled the Swapper task assumes 100% processor occupancy and system performance degenerates. (as evidenced by top)
The kernel version is 2.6.33.3 (I also tried 2.6.39.4). This happens on a minimal system built from buildroot without any other processes running, the only way to recover the situation is with a reboot.
Any ideas or suggestions on what the issue might be?
I was going to try a non-busybox init but before I do that I want to make sure that there is not an available explanation for the behaviour I am observing.
Regards
johnos
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Quoted 5 lines · John OSullivan
Hi,
I?m not sure if this is the correct forum to ask this question but I have seen a few buildroot/busybox references to this problem but none with a clear solution.
The busybox mailing list would probably be more appropriate...
Quoted 36 lines
I am running buildroot-2012-05 with busybox 1.19, using the busybox init with an inittab based on the default one provided.
In the init tab there is a trap for ctrlaltdel
::ctrlaltdel:/sbin/reboot
This line is never called after hitting ctrl alt del on a keyboard
Instead we get a signal pending on the init task
Cat
/proc/1/status---------------------------
Name: swapper
State: R (running)
Tgid: 1
Pid: 1
PPid: 0
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 32
Groups:
Quoted 7 lines
Threads: 1
SigQ: 1/938
SigPnd: 0000000000000100
ShdPnd: 0000000000000002
If I understand correctly, this is a SIGCHLD and a SIGINT. The SIGINT
is sent to init by the kernel when you press ctrlaltdel - so I guess you pressed it twice.
Quoted 11 lines
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000000000000
CapInh: 0000000000000000
After the init process is signalled the Swapper task assumes 100% processor occupancy and system performance degenerates. (as evidenced by top)
That seems to indicate it's getting fork-bombed. You can check that by
running ps; ps from the shell - if the two instances have very different PIDs, then you have a fork bomb :-)
Regards,
Arnout
Quoted 22 lines
The kernel version is 2.6.33.3 (I also tried 2.6.39.4). This happens on a minimal system built from buildroot without any other processes running, the only way to recover the situation is with a reboot.
Any ideas or suggestions on what the issue might be?
I was going to try a non-busybox init but before I do that I want to make sure that there is not an available explanation for the behaviour I am observing.
Regards
johnos
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Signature · 6 lines
Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286500 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle GPG fingerprint: 7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F