Re: ANNOUNCE: Linux Kernel ORB: kORBit

[Mikulas Patocka]

On Mon, 18 Dec 2000, Rik van Riel wrote:

> On Mon, 18 Dec 2000, Andrea Arcangeli wrote:
> > On Mon, Dec 18, 2000 at 06:29:24PM -0200, Rik van Riel wrote:
> > > Wrong. Getblk won't deadlock, it will just sleep and another
> > 
> > getblk will deadlock.
> 
> OUCH. The only protection we have against this is the fact
> that atomic allocations are not allowed to eat up all memory
> in the system and that every thread can only have 1 getblk
> operation at a time, right?

You have small posibility that interrupt will eat up memory - interrupt in
process that has PF_MEMALLOC. Patch: 

--- linux/mm/page_alloc.c_      Mon Dec 18 22:48:47 2000
+++ linux/mm/page_alloc.c       Mon Dec 18 22:53:52 2000
@@ -516,7 +516,7 @@
 
                /* XXX: is pages_min/4 a good amount to reserve for this? */
                if (z->free_pages < z->pages_min / 4 &&
-                               !(current->flags & PF_MEMALLOC))
+                               (!(current->flags & PF_MEMALLOC) || in_interrupt()))
                        continue;
                page = rmqueue(z, order);
                if (page)

Mikulas

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