Re: [PATCH v3 04/26] x86/mm: split out preallocate_sub_pgd()

[Yosry Ahmed]

> >> +
> >> +	/*
> >> +	 * On 4-level systems, the P4D layer is folded away and
> >> +	 * the above code does no preallocation.  Below, go down
> >> +	 * to the pud _software_ level to ensure the second
> >> +	 * hardware level is allocated on 4-level systems too.
> >> +	 */
> >> +	lvl = "pud";
> >> +	pud = pud_alloc(mm, p4d, addr);
> >> +	if (!pud)
> >> +		goto failed;
> >> +	return 0;
> >> +
> >> +failed:
> >> +	pr_warn_ratelimited("Failed to preallocate %s\n", lvl);
> >
> > Can this possibly fire more than once? IIUC we will panic right after
> > returning.
> 
> In the immediate usecase no, but once it's used for
> mm_local_map_to_user() we do actually handle failure.

Oh yeah I missed this, thanks.