Re: [PATCH] mm: return -ENOMEM for page-table allocation failure in insert_pages()

[Andrew Morton]

On Thu, 30 Jul 2026 08:42:49 +0100 "Lorenzo Stoakes (ARM)" <ljs@xxxxxxxxxx> wrote:

> 	pages_to_write_in_pmd = min_t(unsigned long,
> 		remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
> 
> 	/* Allocate the PTE if necessary; takes PMD lock once only. */
> 	ret = -ENOMEM; <------------------------------ set it again?
> 	if (pte_alloc(mm, pmd))
> 		goto out;
> 
> The way this function is written is horrible in general, I hate 'preset default
> return value' as a pattern.

It used to be the preferred way because 

	ret = -ENOMEM;
	if (expr)
		goto out;

generated slightly better code than

	if (expr) {
		ret = -ENOMEM;
		goto out;
	}

Whether that is the case with current compilers I don't know.