Messages in this thread | | | Date | Sun, 5 Aug 2007 13:54:03 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 4/5] UML - Simplify helper stack handling |
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On Sun, 5 Aug 2007 22:41:14 +0200 Luca Tettamanti <kronos.it@gmail.com> wrote:
> Il Wed, Jun 27, 2007 at 11:37:01PM -0700, Andrew Morton ha scritto: > > > > So I'm running the generic version of this on i386 with 8k stacks (below), > > with a quick LTP run. > > > > Holy cow, either we use a _lot_ of stack or these numbers are off: > > > > vmm:/home/akpm> dmesg -s 1000000|grep 'bytes left' > > khelper used greatest stack depth: 7176 bytes left > > khelper used greatest stack depth: 7064 bytes left > > khelper used greatest stack depth: 6840 bytes left > > khelper used greatest stack depth: 6812 bytes left > > hostname used greatest stack depth: 6636 bytes left > > uname used greatest stack depth: 6592 bytes left > > uname used greatest stack depth: 6284 bytes left > > hotplug used greatest stack depth: 5568 bytes left > > rpc.nfsd used greatest stack depth: 5136 bytes left > > chown02 used greatest stack depth: 4956 bytes left > > fchown01 used greatest stack depth: 4892 bytes left > > > > That's the sum of process stack and interrupt stack, but I doubt if this > > little box is using much interrupt stack space. > > > > No wonder people are still getting stack overflows with 4k stacks... > > Hi Andrew, > I was a bit worried about stack usage on my setup and google found your > mail :P > > FYI: > > khelper used greatest stack depth: 3228 bytes left > khelper used greatest stack depth: 3124 bytes left > busybox used greatest stack depth: 2808 bytes left > modprobe used greatest stack depth: 2744 bytes left > busybox used greatest stack depth: 2644 bytes left > modprobe used greatest stack depth: 1836 bytes left > modprobe used greatest stack depth: 1176 bytes left > java used greatest stack depth: 932 bytes left > java used greatest stack depth: 540 bytes left > > I'm running git-current, with 4KiB stacks; filesystems are ext3 and XFS > on LVM (on libata devices). > Does it make sense to raise STACK_WARN to get a stack trace in do_IRQ? > Or is 540 bytes still "safe" taking into account the separate IRQ stack? >
540 bytes free means that we've used 90% of the stack. I'd say it is extremely unsafe.
Unbelieveably unsafe. I'm suspecting that the instrumentation is lying to us for some reason.
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