Re: [PATCH 01/15] mm: poison struct page for ptlock

[Hugh Dickins]

On Thu, 10 Nov 2005, Andrew Morton wrote:
> Hugh Dickins <hugh@xxxxxxxxxxx> wrote:
> > On Thu, 10 Nov 2005, Ingo Molnar wrote:
> > > 
> > > yuck. What is the real problem btw? AFAICS there's enough space for a 
> > > 2-word spinlock in struct page for pagetables.
> > 
> > Yes.  There is no real problem.  But my patch offends good taste.
> 
> Isn't it going to overrun page.lru with CONFIG_DEBUG_SPINLOCK?

No.  There is just one case where it would,
so in that case split ptlock is disabled by mm/Kconfig's
# PA-RISC 7xxx's debug spinlock_t is too large for 32-bit struct page.

	default "4096" if PARISC && DEBUG_SPINLOCK && !PA20

Of course, someone may extend spinlock debugging info tomorrow; but
when they do, presumably they'll try it out, and hit the BUILD_BUG_ON.
They'll then probably want to extend the suppression in mm/Kconfig.

Hugh
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/