Re: kernel malloc

[Artur Grabowski <art@blahonga.org>]

Wouter Clarie <rimshot@pandora.be> writes:

> Hi,
> 
> in malloc(9) you can find that if using kernel malloc with M_WAITOK, it
> can never return NULL. Is this true in 100% of the cases? I'm doing a
> return value check of kernelland and there are quite a few cases where the
> return value is still checked when using M_WAITOK.
> 
> Could anyone make this clear?

Sometimes I do a sweep for checked return values from M_WAITOK malloc. But
it was a long time ago last time.

When kernel malloc with M_WAITOK can fail it will panic with "out of space
in kmem_map" instead. It will never return NULL. The documentation is right.
People check the return value because they are used to, I guess the kernel
malloc shouldn't be called malloc if it doesn't have the same API and
semantics as userland, but I'm not going to change that.

//art