Re: [parisc-linux] 2.5 randomly kills applications with page faults

[Randolph Chung <randolph@tausq.org>]

> In debugging the problems, so far it has always been stack manipulation 
> instructions in the user level code causing this.  Further, on adding a 

ditto.... there's a note about this in the todo....

> register dump to the page fault debugging code, the reason is that the stack 
> pointer is way out of where it should be for a user process (around 0x4f000), 
> so I surmise it got clobbered on a rare return path from kernel to user.

> Does anyone have any additional information and pointers?  I'm trying to audit 
> entry.S to see if there is a little used path that can clobber the stack, but 
> my parisc assembly isn't the best...
> 

that's what i thought too, so i went through entry.S as well to see what
i can find. haven't found anything yet :(

i was able to get the kernel to die simply by having a program do
gettimeofday() in a loop with 2.5...  i would guess it's a case where we
have to do some work on the syscall return path (resched, softirq, etc)
that's clobbering things, but i don't know what it is.

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/