Re: [PATCH 10/10] mm: refactor va_remove_mappings

[Uladzislau Rezki <urezki@gmail.com>]

On Thu, Jan 19, 2023 at 11:02:26AM +0100, Christoph Hellwig wrote:
> Move the VM_FLUSH_RESET_PERMS to the caller and rename the function
> to better describe what it is doing.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  mm/vmalloc.c | 27 ++++++++-------------------
>  1 file changed, 8 insertions(+), 19 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 791d906d7e407c..f41be986b01e4e 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2617,35 +2617,23 @@ static inline void set_area_direct_map(const struct vm_struct *area,
>  			set_direct_map(area->pages[i]);
>  }
>  
> -/* Handle removing and resetting vm mappings related to the vm_struct. */
> -static void va_remove_mappings(struct vm_struct *area, int deallocate_pages)
> +/*
> + * Flush the vm mapping and reset the direct map.
> + */
> +static void vm_reset_perms(struct vm_struct *area)
>  {
>  	unsigned long start = ULONG_MAX, end = 0;
>  	unsigned int page_order = vm_area_page_order(area);
> -	int flush_reset = area->flags & VM_FLUSH_RESET_PERMS;
>  	int flush_dmap = 0;
>  	int i;
>  
> -	/* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */
> -	if (!flush_reset)
> -		return;
> -
> -	/*
> -	 * If not deallocating pages, just do the flush of the VM area and
> -	 * return.
> -	 */
> -	if (!deallocate_pages) {
> -		vm_unmap_aliases();
> -		return;
> -	}
> -
>  	/*
> -	 * If execution gets here, flush the vm mapping and reset the direct
> -	 * map. Find the start and end range of the direct mappings to make sure
> +	 * Find the start and end range of the direct mappings to make sure that
>  	 * the vm_unmap_aliases() flush includes the direct map.
>  	 */
>  	for (i = 0; i < area->nr_pages; i += 1U << page_order) {
>  		unsigned long addr = (unsigned long)page_address(area->pages[i]);
> +
>  		if (addr) {
>  			unsigned long page_size;
>  
> @@ -2740,7 +2728,8 @@ void vfree(const void *addr)
>  		return;
>  	}
>  
> -	va_remove_mappings(vm, true);
> +	if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS))
> +		vm_reset_perms(vm);
>  	for (i = 0; i < vm->nr_pages; i++) {
>  		struct page *page = vm->pages[i];
>  
> -- 
> 2.39.0
> 
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

--
Uladzislau Rezki