Re: [RFC PATCH] binfmt_elf: Align eligible read-only PT_LOAD segments to PMD_SIZE for THP

[Matthew Wilcox]

On Mon, Mar 02, 2026 at 11:50:46PM +0800, WANG Rui wrote:
> +config ELF_RO_LOAD_THP_ALIGNMENT
> +	bool "Align read-only ELF load segments for THP (EXPERIMENTAL)"
> +	depends on READ_ONLY_THP_FOR_FS

This doesn't deserve a config option.

> +#if defined(CONFIG_ELF_RO_LOAD_THP_ALIGNMENT) && PMD_SIZE <= SZ_32M

Why 32MB?  This is weird and not justified anywhere.

> +			if (hugepage_global_always() && !(cmds[i].p_flags & PF_W)
> +				&& IS_ALIGNED(cmds[i].p_vaddr | cmds[i].p_offset, PMD_SIZE)
> +				&& cmds[i].p_filesz >= PMD_SIZE && p_align < PMD_SIZE)
> +				p_align = PMD_SIZE;

Normal style is to put the '&&' at the end of the line:

			if (!(cmds[i].p_flags & PF_W) &&
			    IS_ALIGNED(cmds[i].p_vaddr | cmds[i].p_offset, PMD_SIZE) &&
			    cmds[i].p_filesz >= PMD_SIZE && p_align < PMD_SIZE))
				p_align = PMD_SIZE;

But this conditional is too complex to be at this level of indentation.
Factor it out into a helper:

			if (align_to_pmd(cmds) && p_align < PMD_SIZE)
				p_align = PMD_SIZE;