Re: 4KSTACKS + DEBUG_STACKOVERFLOW harmful

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Aug 29, 2007, at 19:01:57, Eric Sandeen wrote:
Jesper Juhl wrote:
A first step could be to allocate those two char arrays with kmalloc() instead of on the stack, but then I guess that dump_stack () gets called from places where we may not really want to be calling kmalloc(). I guess we could allocate the buffers earlier (like at boot time) and store pointers somewhere where dump stack can get to them later when it needs them.
Yep, I thought about something like that... and I assume you'd need  
a bit of locking around them too.
How about turning off preemption and using a per-CPU buffer?   
Alternatively you could turn off IRQs, poke a per-CPU value to clue  
in any incoming NMIs, and switch to a separate stack.  I suppose if  
you wanted it to work with all of 16 bytes of stack left on both  
thread and IRQ stacks, you could have separate per-CPU NMI stacks;  
the stack-dump would be poking a special per-CPU value and sending  
ourselves an NMI.
There are probably a half dozen other variants on ways to run  
screaming to the CPU saying "It hurts mommy!" and get a new stack in  
which we can play for a while.
Cheers,
Kyle Moffett
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux