Re: [PATCH v2] mm: add more readable thp_vma_allowable_order_foo()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On 2024/4/25 12:00, Matthew Wilcox wrote:
> On Thu, Apr 25, 2024 at 11:51:08AM +0800, Kefeng Wang wrote:
>> There are too many bool arguments in thp_vma_allowable_orders(), adding
>> some more readable thp_vma_allowable_order_foo(),
> 
> Here's an alternative approach I came up with and forgot to send out.
> I take no position on which is better.

Always confuse, either way is fine, even combine the two way, let's see
Ryan/David's option.

> 
> commit a761d4b9cf14
> Author: Matthew Wilcox (Oracle) <willy@infradead.org>
> Date:   Tue Apr 16 00:25:09 2024 -0400
> 
>      mm: Simplify thp_vma_allowable_order
>      
>      Combine the three boolean arguments into one flags argument for
>      readability.
>      
>      Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 23fbab954c20..0ffa8902f973 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -866,8 +866,8 @@ 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(vma, vma->vm_flags,
> +			   TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL));
>   
>   	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 de0c89105076..0d0ba39b86ae 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -84,8 +84,12 @@ 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 TVA_SMAPS		(1 << 0)	/* Will be used for procfs */
> +#define TVA_IN_PF		(1 << 1)	/* Page fault handler */
> +#define TVA_ENFORCE_SYSFS	(1 << 2)	/* Obey sysfs configuration */
> +
> +#define thp_vma_allowable_order(vma, vm_flags, tva_flags, order) \
> +	(!!thp_vma_allowable_orders(vma, vm_flags, tva_flags, BIT(order)))
>   
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>   #define HPAGE_PMD_SHIFT PMD_SHIFT
> @@ -210,17 +214,15 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
>   }
>   
>   unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
> -					 unsigned long vm_flags, bool smaps,
> -					 bool in_pf, bool enforce_sysfs,
> +					 unsigned long vm_flags,
> +					 unsigned long tva_flags,
>   					 unsigned long orders);
>   
>   /**
>    * thp_vma_allowable_orders - determine hugepage orders that are allowed for vma
>    * @vma:  the vm area to check
>    * @vm_flags: use these vm_flags instead of vma->vm_flags
> - * @smaps: whether answer will be used for smaps file
> - * @in_pf: whether answer will be used by page fault handler
> - * @enforce_sysfs: whether sysfs config should be taken into account
> + * @tva_flags: Which TVA flags to honour
>    * @orders: bitfield of all orders to consider
>    *
>    * Calculates the intersection of the requested hugepage orders and the allowed
> @@ -233,12 +235,12 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
>    */
>   static inline
>   unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
> -				       unsigned long vm_flags, bool smaps,
> -				       bool in_pf, bool enforce_sysfs,
> +				       unsigned long vm_flags,
> +				       unsigned long tva_flags,
>   				       unsigned long orders)
>   {
>   	/* Optimization to check if required orders are enabled early. */
> -	if (enforce_sysfs && vma_is_anonymous(vma)) {
> +	if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) {
>   		unsigned long mask = READ_ONCE(huge_anon_orders_always);
>   
>   		if (vm_flags & VM_HUGEPAGE)
> @@ -252,8 +254,7 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
>   			return 0;
>   	}
>   
> -	return __thp_vma_allowable_orders(vma, vm_flags, smaps, in_pf,
> -					  enforce_sysfs, orders);
> +	return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders);
>   }
>   
>   #define transparent_hugepage_use_zero_page()				\
> @@ -404,8 +405,8 @@ static inline unsigned long thp_vma_suitable_orders(struct vm_area_struct *vma,
>   }
>   
>   static inline unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
> -					unsigned long vm_flags, bool smaps,
> -					bool in_pf, bool enforce_sysfs,
> +					unsigned long vm_flags,
> +					unsigned long tva_flags,
>   					unsigned long orders)
>   {
>   	return 0;
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 8bc4ffd4725e..5d3d9c0c4153 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -80,10 +80,13 @@ unsigned long huge_anon_orders_madvise __read_mostly;
>   unsigned long huge_anon_orders_inherit __read_mostly;
>   
>   unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
> -					 unsigned long vm_flags, bool smaps,
> -					 bool in_pf, bool enforce_sysfs,
> +					 unsigned long vm_flags,
> +					 unsigned long tva_flags,
>   					 unsigned long orders)
>   {
> +	bool smaps = tva_flags & TVA_SMAPS;
> +	bool in_pf = tva_flags & TVA_IN_PF;
> +	bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS;
>   	/* Check the intersection of requested and supported orders. */
>   	orders &= vma_is_anonymous(vma) ?
>   			THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE;
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 38830174608f..9642d3c6ee7e 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -453,7 +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,
> +		if (thp_vma_allowable_order(vma, vm_flags, TVA_ENFORCE_SYSFS,
>   					    PMD_ORDER))
>   			__khugepaged_enter(vma->vm_mm);
>   	}
> @@ -917,6 +917,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>   				   struct collapse_control *cc)
>   {
>   	struct vm_area_struct *vma;
> +	unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
>   
>   	if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
>   		return SCAN_ANY_PROCESS;
> @@ -927,8 +928,7 @@ 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_order(vma, vma->vm_flags, tva_flags, PMD_ORDER))
>   		return SCAN_VMA_CHECK;
>   	/*
>   	 * Anon VMA expected, the address may be unmapped then
> @@ -1510,8 +1510,7 @@ 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_order(vma, vma->vm_flags, 0, PMD_ORDER))
>   		return SCAN_VMA_CHECK;
>   
>   	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
> @@ -2376,8 +2375,8 @@ 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_order(vma, vma->vm_flags,
> +					TVA_ENFORCE_SYSFS, PMD_ORDER)) {
>   skip:
>   			progress++;
>   			continue;
> @@ -2714,8 +2713,7 @@ 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_order(vma, vma->vm_flags, 0, PMD_ORDER))
>   		return -EINVAL;
>   
>   	cc = kmalloc(sizeof(*cc), GFP_KERNEL);
> diff --git a/mm/memory.c b/mm/memory.c
> index 5624b881b662..287f7d6eb9ed 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4346,8 +4346,8 @@ 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(vma, vma->vm_flags,
> +			TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
>   	orders = thp_vma_suitable_orders(vma, vmf->address, orders);
>   
>   	if (!orders)
> @@ -5395,7 +5395,8 @@ 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(vma, vm_flags,
> +				TVA_IN_PF | TVA_ENFORCE_SYSFS, PUD_ORDER)) {
>   		ret = create_huge_pud(&vmf);
>   		if (!(ret & VM_FAULT_FALLBACK))
>   			return ret;
> @@ -5429,7 +5430,8 @@ 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(vma, vm_flags,
> +				TVA_IN_PF | TVA_ENFORCE_SYSFS, PMD_ORDER)) {
>   		ret = create_huge_pmd(&vmf);
>   		if (!(ret & VM_FAULT_FALLBACK))
>   			return ret;