Re: [patch] 2.3.99-pre6-3 VM fixed

[Rik van Riel <riel@conectiva.com.br>]

On Thu, 27 Apr 2000, Stephen C. Tweedie wrote:
> On Wed, Apr 26, 2000 at 10:36:10AM -0300, Rik van Riel wrote:
> > 
> > The patch runs great in a variety of workloads I've tested here,
> > but of course I'm not sure if it works as good as it should in
> > *your* workload, so testing is wanted/needed/appreciated...
> 
> Well, on an 8GB box doing a "mtest -m1000 -r0 -w12" (ie. create
> 1GB heap and fork off 12 writer sub-processes touching the heap
> at random), I get a complete lockup just after the system goes
> into swap.  At one point I was able to capture an EIP trace
> showing the kernel looping in stext_lock and try_to_swap_out.

After half a day of heavy abuse, I've gotten my machine into
a state where it's hanging in stext_lock and swap_out...

Both cpus are spinning in a very tight loop, suggesting a
deadlock. (/me points finger at other code, I didn't change
any locking stuff :))

This suggests a locking issue. Is there any place in the kernel
where we take a write lock on tasklist_lock and do a lock_kernel()
afterwards?

Alternatively, the mm->lock, kernel_lock and/or tasklist_lock could
be in play all three... Could the changes to ptrace.c be involved
here?

regards,

Rik
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