Re: [PATCH] mm: add more readable thp_vma_allowable_order_foo()

[Ryan Roberts <ryan.roberts@arm.com>]

On 24/04/2024 15:07, Kefeng Wang wrote:
> There are too many bool arguments in thp_vma_allowable_orders(), adding
> some more readable thp_vma_allowable_order_foo(),
> 
>   thp_vma_allowable_orders_insmaps() is used in samps
>   thp_vma_allowable_order[s]_inpf()  is used in page fault
>   thp_vma_allowable_pmd_order_inhuge is used in khugepaged scan and madvise
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Just one nit below. With that addressed:

Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>

> ---
>  fs/proc/task_mmu.c      |  3 +--
>  include/linux/huge_mm.h | 14 ++++++++++++--
>  mm/khugepaged.c         | 20 ++++++++------------
>  mm/memory.c             |  8 ++++----
>  4 files changed, 25 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index f4259b7edfde..1136aa97f143 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -871,8 +871,7 @@ static int show_smap(struct seq_file *m, void *v)
>  	__show_smap(m, &mss, false);
>  
>  	seq_printf(m, "THPeligible:    %8u\n",
> -		   !!thp_vma_allowable_orders(vma, vma->vm_flags, true, false,
> -					      true, THP_ORDERS_ALL));
> +		   thp_vma_allowable_orders_insmaps(vma, vma->vm_flags));
>  
>  	if (arch_pkeys_enabled())
>  		seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 56c7ea73090b..345cf394480b 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -83,8 +83,18 @@ extern struct kobj_attribute shmem_enabled_attr;
>   */
>  #define THP_ORDERS_ALL		(THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE)
>  
> -#define thp_vma_allowable_order(vma, vm_flags, smaps, in_pf, enforce_sysfs, order) \
> -	(!!thp_vma_allowable_orders(vma, vm_flags, smaps, in_pf, enforce_sysfs, BIT(order)))
> +#define thp_vma_allowable_orders_insmaps(vma, vm_flags) \
> +	(!!thp_vma_allowable_orders(vma, vm_flags, true, false, true, THP_ORDERS_ALL))
> +
> +#define thp_vma_allowable_orders_inpf(vma, vm_flags, orders) \
> +	(!!thp_vma_allowable_orders(vma, vm_flags, false, true, true, orders))
> +
> +#define thp_vma_allowable_order_inpf(vma, vm_flags, order) \
> +	(!!thp_vma_allowable_orders_inpf(vma, vm_flags, BIT(order)))
> +
> +#define thp_vma_allowable_pmd_order_inhuge(vma, vm_flags, enforce_sysfs) \
> +	(!!thp_vma_allowable_orders(vma, vm_flags, false, false, enforce_sysfs, BIT(PMD_ORDER)))

nit: Personally I'd leave the order as an argument rather than encoding it in
the name. It's likely that khugepaged will grow support for non-PMD-size
collapse in future. The first part of the name "thp_vma_allowable_order" is then
consistent and easy to search for all variants. And perhaps "inkhuge" is more
precise?

> +
>  
>  #ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
>  #define HPAGE_PMD_SHIFT PMD_SHIFT
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 2f73d2aa9ae8..5a27dccfda02 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -453,8 +453,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
>  {
>  	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
>  	    hugepage_flags_enabled()) {
> -		if (thp_vma_allowable_order(vma, vm_flags, false, false, true,
> -					    PMD_ORDER))
> +		if (thp_vma_allowable_pmd_order_inhuge(vma, vm_flags, true))
>  			__khugepaged_enter(vma->vm_mm);
>  	}
>  }
> @@ -909,15 +908,15 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>  
>  	if (!thp_vma_suitable_order(vma, address, PMD_ORDER))
>  		return SCAN_ADDRESS_RANGE;
> -	if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false,
> -				     cc->is_khugepaged, PMD_ORDER))
> +	if (!thp_vma_allowable_pmd_order_inhuge(vma, vma->vm_flags,
> +						cc->is_khugepaged))
>  		return SCAN_VMA_CHECK;
>  	/*
>  	 * Anon VMA expected, the address may be unmapped then
>  	 * remapped to file after khugepaged reaquired the mmap_lock.
>  	 *
> -	 * thp_vma_allowable_order may return true for qualified file
> -	 * vmas.
> +	 * thp_vma_allowable_pmd_order_inhuge may return true for
> +	 * qualified file vmas.
>  	 */
>  	if (expect_anon && (!(*vmap)->anon_vma || !vma_is_anonymous(*vmap)))
>  		return SCAN_PAGE_ANON;
> @@ -1493,8 +1492,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
>  	 * and map it by a PMD, regardless of sysfs THP settings. As such, let's
>  	 * analogously elide sysfs THP settings here.
>  	 */
> -	if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, false,
> -				     PMD_ORDER))
> +	if (!thp_vma_allowable_pmd_order_inhuge(vma, vma->vm_flags, false))
>  		return SCAN_VMA_CHECK;
>  
>  	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
> @@ -2355,8 +2353,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
>  			progress++;
>  			break;
>  		}
> -		if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false,
> -					     true, PMD_ORDER)) {
> +		if (!thp_vma_allowable_pmd_order_inhuge(vma, vma->vm_flags, true)) {
>  skip:
>  			progress++;
>  			continue;
> @@ -2693,8 +2690,7 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
>  
>  	*prev = vma;
>  
> -	if (!thp_vma_allowable_order(vma, vma->vm_flags, false, false, false,
> -				     PMD_ORDER))
> +	if (!thp_vma_allowable_pmd_order_inhuge(vma, vma->vm_flags, false))
>  		return -EINVAL;
>  
>  	cc = kmalloc(sizeof(*cc), GFP_KERNEL);
> diff --git a/mm/memory.c b/mm/memory.c
> index 09ed76e5b8c0..8507bfda461a 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4329,8 +4329,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
>  	 * for this vma. Then filter out the orders that can't be allocated over
>  	 * the faulting address and still be fully contained in the vma.
>  	 */
> -	orders = thp_vma_allowable_orders(vma, vma->vm_flags, false, true, true,
> -					  BIT(PMD_ORDER) - 1);
> +	orders = thp_vma_allowable_orders_inpf(vma, vma->vm_flags,
> +					       BIT(PMD_ORDER) - 1);
>  	orders = thp_vma_suitable_orders(vma, vmf->address, orders);
>  
>  	if (!orders)
> @@ -5433,7 +5433,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
>  		return VM_FAULT_OOM;
>  retry_pud:
>  	if (pud_none(*vmf.pud) &&
> -	    thp_vma_allowable_order(vma, vm_flags, false, true, true, PUD_ORDER)) {
> +	    thp_vma_allowable_order_inpf(vma, vm_flags, PUD_ORDER)) {
>  		ret = create_huge_pud(&vmf);
>  		if (!(ret & VM_FAULT_FALLBACK))
>  			return ret;
> @@ -5467,7 +5467,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
>  		goto retry_pud;
>  
>  	if (pmd_none(*vmf.pmd) &&
> -	    thp_vma_allowable_order(vma, vm_flags, false, true, true, PMD_ORDER)) {
> +	    thp_vma_allowable_order_inpf(vma, vm_flags, PMD_ORDER)) {
>  		ret = create_huge_pmd(&vmf);
>  		if (!(ret & VM_FAULT_FALLBACK))
>  			return ret;