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It's very easy to freeze a system as a non-root user; cause too many interrupts, consume too many resources, etc. Many kinds of infinite loop will lock a system

It's very easy to freeze a system as a non-root user; cause too many interrupts, consume too many resources, etc. Many kinds of infinite loop will lock a system hard. Hell, you can crash systems with too many packets. And it's very easy to cause ps to hang. Many different kernel syscalls hang / are blocking. Mostly you see this with kernel features dependent on a resource that doesn't resolve itself, like a stuck disk, network filesystem, etc. But other various quirks of the system can cause blocking.

adrian_b 4y ago
While what you say is true, these are nonetheless kernel bugs. The kernel should never let any user process consume so many resources as to cause a system freeze. The kernel must not only be able to preempt any user process at any time, stopping it to consume all CPU time, but it must also prevent any user process to completely fill a SSD or HDD, because that can prevent many programs from starting.
- throwawaaarrgh 4y ago
  Preemptibility is an optional kernel design feature. Not all kernels have it and not in all ways. If it's intentionally designed that way it's not a bug. No kernel stops users from filling up disks (though some filesystems have such limits as features, which most of us turn off) Pretty much the only kernels that are totally preemptible are RTOS and they still don't stop you from shooting yourself in the foot.
- astrange 4y ago
  A computer's job is to do whatever you ask it to do; that includes using all disk or memory up, if that's what you really want. There's not really a way to prevent breaking the OS (or just using up the battery) without preventing you from using all the computer you bought. A phone is different since it always has to be able to make phone calls.
deleted 4y ago
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mort96 4y ago
The things you mention cause "freezing" by asking the kernel to do too much so that it doesn't have time to deal with other stuff. Those issues are unfortunate, but really hard to completely avoid. The interesting thing here is that the described bug isn't just overloading the kernel with work or starving it of resources, it's something which seems completely innocent.

adrian_b 4y ago

While what you say is true, these are nonetheless kernel bugs. The kernel should never let any user process consume so many resources as to cause a system freeze. The kernel must not only be able to preempt any user process at any time, stopping it to consume all CPU time, but it must also prevent any user process to completely fill a SSD or HDD, because that can prevent many programs from starting.

throwawaaarrgh 4y ago
Preemptibility is an optional kernel design feature. Not all kernels have it and not in all ways. If it's intentionally designed that way it's not a bug. No kernel stops users from filling up disks (though some filesystems have such limits as features, which most of us turn off) Pretty much the only kernels that are totally preemptible are RTOS and they still don't stop you from shooting yourself in the foot.
astrange 4y ago
A computer's job is to do whatever you ask it to do; that includes using all disk or memory up, if that's what you really want. There's not really a way to prevent breaking the OS (or just using up the battery) without preventing you from using all the computer you bought. A phone is different since it always has to be able to make phone calls.

deleted 4y ago

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mort96 4y ago

The things you mention cause "freezing" by asking the kernel to do too much so that it doesn't have time to deal with other stuff. Those issues are unfortunate, but really hard to completely avoid. The interesting thing here is that the described bug isn't just overloading the kernel with work or starving it of resources, it's something which seems completely innocent.