Theodore Ts'o wrote:
> On a 32-bit system, while running aio-stress, I got the following kernel
> message:
>
> aio-stress used greatest stack depth: 372 bytes left
>
> That's a bit close for comfort; we may want to see if we have some
> especially piggy on-stack allocations on the AIO code paths.
>
> - Ted
Ted, you might try the built-in stack depth tracing stuff:
config STACK_TRACER
bool "Trace max stack"
depends on HAVE_FUNCTION_TRACER
select FUNCTION_TRACER
select STACKTRACE
select KALLSYMS
help
This special tracer records the maximum stack footprint of the
kernel and displays it in debugfs/tracing/stack_trace.
This tracer works by hooking into every function call that the
kernel executes, and keeping a maximum stack depth value and
stack-trace saved. If this is configured with DYNAMIC_FTRACE
then it will not have any overhead while the stack tracer
is disabled.
To enable the stack tracer on bootup, pass in 'stacktrace'
on the kernel command line.
The stack tracer can also be enabled or disabled via the
sysctl kernel.stack_tracer_enabled
Say N if unsure.
if you got within 372 bytes on 32-bit (with 8k stacks) then that's
indeed pretty worrisome.
-Eric
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