Re: [PATCH] kmalloc: Return NULL instead of link failure

[Pekka Enberg]

Andrew Morton wrote:
> On Tue, 20 Jan 2009 10:53:26 -0500
> Jeff Mahoney <jeffm@xxxxxxxx> wrote:
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> >  The SLAB kmalloc with a constant value isn't consistent with the other
> >  implementations because it bails out with __you_cannot_kmalloc_that_much
> >  rather than returning NULL and properly allowing the caller to fall back
> >  to vmalloc or take other action. This doesn't happen with a non-constant
> >  value or with SLOB or SLUB.
> >
> >  Starting with 2.6.28, I've been seeing build failures on s390x. This is
> >  due to init_section_page_cgroup trying to allocate 2.5MB when the max
> >  size for a kmalloc on s390x is 2MB.
> >
> >  It's failing because the value is constant. The workarounds at the call
> >  size are ugly and the caller shouldn't have to change behavior depending
> >  on what the backend of the API is.
> >
> >  So, this patch eliminates the link failure and returns NULL like the
> >  other implementations.
>
> OK by me, is that's what the other sl[abcd...xyz]b.c implementations
> do.
>
> That __you_cannot_kmalloc_that_much() thing has frequently been a PITA
> anyway - some gcc versions flub the constant_p() test and end up
> referencing __you_cannot_kmalloc_that_much() when the callsite was
> passing a variable `size' arg.

[snip]

> Strange patch format, but it applied.
>
> I'll punt this patch in the Pekka direction.

Applied, thanks!

		Pekka
--
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/