[PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call

Lorenzo Stoakes (Oracle) posted 9 patches 2 weeks, 3 days ago
There is a newer version of this series
[PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Lorenzo Stoakes (Oracle) 2 weeks, 3 days ago
Rather than having separate logic for each case determining whether to zap
the deposited table, simply track this via a boolean.

We check separately if the architecture requires it.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
 mm/huge_memory.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 499c31bf8f83..c4e00c645e58 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2431,6 +2431,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		 pmd_t *pmd, unsigned long addr)
 {
 	struct folio *folio = NULL;
+	bool needs_deposit = false;
 	bool flush_needed = false;
 	spinlock_t *ptl;
 	pmd_t orig_pmd;
@@ -2450,23 +2451,18 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 						tlb->fullmm);
 	arch_check_zapped_pmd(vma, orig_pmd);
 	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
-	if (vma_is_special_huge(vma)) {
-		if (arch_needs_pgtable_deposit())
-			zap_deposited_table(tlb->mm, pmd);
+	if (vma_is_special_huge(vma))
 		goto out;
-	}
 	if (is_huge_zero_pmd(orig_pmd)) {
-		if (!vma_is_dax(vma) || arch_needs_pgtable_deposit())
-			zap_deposited_table(tlb->mm, pmd);
+		needs_deposit = !vma_is_dax(vma);
 		goto out;
 	}
 
 	if (pmd_present(orig_pmd)) {
-		struct page *page = pmd_page(orig_pmd);
+		folio = pmd_folio(orig_pmd);
 
 		flush_needed = true;
-		folio = page_folio(page);
-		folio_remove_rmap_pmd(folio, page, vma);
+		folio_remove_rmap_pmd(folio, &folio->page, vma);
 		WARN_ON_ONCE(folio_mapcount(folio) < 0);
 	} else if (pmd_is_valid_softleaf(orig_pmd)) {
 		const softleaf_t entry = softleaf_from_pmd(orig_pmd);
@@ -2481,11 +2477,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	}
 
 	if (folio_test_anon(folio)) {
-		zap_deposited_table(tlb->mm, pmd);
+		needs_deposit = true;
 		add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
 	} else {
-		if (arch_needs_pgtable_deposit())
-			zap_deposited_table(tlb->mm, pmd);
 		add_mm_counter(tlb->mm, mm_counter_file(folio),
 			       -HPAGE_PMD_NR);
 
@@ -2505,6 +2499,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	}
 
 out:
+	if (arch_needs_pgtable_deposit() || needs_deposit)
+		zap_deposited_table(tlb->mm, pmd);
+
 	spin_unlock(ptl);
 	if (flush_needed)
 		tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
-- 
2.53.0
Re: [PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Kiryl Shutsemau 2 weeks, 3 days ago
On Thu, Mar 19, 2026 at 01:00:13PM +0000, Lorenzo Stoakes (Oracle) wrote:
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 499c31bf8f83..c4e00c645e58 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2431,6 +2431,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>  		 pmd_t *pmd, unsigned long addr)
>  {
>  	struct folio *folio = NULL;
> +	bool needs_deposit = false;

I think 'has_deposit' is a better name here.

And initialize it to arch_needs_pgtable_deposit().

-- 
  Kiryl Shutsemau / Kirill A. Shutemov
Re: [PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Lorenzo Stoakes (Oracle) 2 weeks, 3 days ago
On Thu, Mar 19, 2026 at 05:03:10PM +0000, Kiryl Shutsemau wrote:
> On Thu, Mar 19, 2026 at 01:00:13PM +0000, Lorenzo Stoakes (Oracle) wrote:
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 499c31bf8f83..c4e00c645e58 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -2431,6 +2431,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> >  		 pmd_t *pmd, unsigned long addr)
> >  {
> >  	struct folio *folio = NULL;
> > +	bool needs_deposit = false;
>
> I think 'has_deposit' is a better name here.

That's fine, can rename.

>
> And initialize it to arch_needs_pgtable_deposit().

Yeah I considered that, but then you have to do logic like:

has_deposit = has_deposit || <whatever>;

Which is a bit ugly.

Could do

has_deposit |= <whatever>

But then that's weird with bools.

Could be has_non_arch_deposit but that's too long and... yeah :>)

>
> --
>   Kiryl Shutsemau / Kirill A. Shutemov

Cheers, Lorenzo
Re: [PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Kiryl Shutsemau 2 weeks, 3 days ago
On Thu, Mar 19, 2026 at 05:18:11PM +0000, Lorenzo Stoakes (Oracle) wrote:
> On Thu, Mar 19, 2026 at 05:03:10PM +0000, Kiryl Shutsemau wrote:
> > On Thu, Mar 19, 2026 at 01:00:13PM +0000, Lorenzo Stoakes (Oracle) wrote:
> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > index 499c31bf8f83..c4e00c645e58 100644
> > > --- a/mm/huge_memory.c
> > > +++ b/mm/huge_memory.c
> > > @@ -2431,6 +2431,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> > >  		 pmd_t *pmd, unsigned long addr)
> > >  {
> > >  	struct folio *folio = NULL;
> > > +	bool needs_deposit = false;
> >
> > I think 'has_deposit' is a better name here.
> 
> That's fine, can rename.
> 
> >
> > And initialize it to arch_needs_pgtable_deposit().
> 
> Yeah I considered that, but then you have to do logic like:
> 
> has_deposit = has_deposit || <whatever>;
> 
> Which is a bit ugly.

You are overthinking it. Just do

	if (!vma_is_dax(vma))
		has_deposit = true;

No need in squeezing it into single line.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov
Re: [PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Lorenzo Stoakes (Oracle) 2 weeks, 2 days ago
On Thu, Mar 19, 2026 at 09:56:53PM +0000, Kiryl Shutsemau wrote:
> On Thu, Mar 19, 2026 at 05:18:11PM +0000, Lorenzo Stoakes (Oracle) wrote:
> > On Thu, Mar 19, 2026 at 05:03:10PM +0000, Kiryl Shutsemau wrote:
> > > On Thu, Mar 19, 2026 at 01:00:13PM +0000, Lorenzo Stoakes (Oracle) wrote:
> > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > > index 499c31bf8f83..c4e00c645e58 100644
> > > > --- a/mm/huge_memory.c
> > > > +++ b/mm/huge_memory.c
> > > > @@ -2431,6 +2431,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> > > >  		 pmd_t *pmd, unsigned long addr)
> > > >  {
> > > >  	struct folio *folio = NULL;
> > > > +	bool needs_deposit = false;
> > >
> > > I think 'has_deposit' is a better name here.
> >
> > That's fine, can rename.
> >
> > >
> > > And initialize it to arch_needs_pgtable_deposit().
> >
> > Yeah I considered that, but then you have to do logic like:
> >
> > has_deposit = has_deposit || <whatever>;
> >
> > Which is a bit ugly.
>
> You are overthinking it. Just do

Well I would argue you're overthinking the review comments here ;)

>
> 	if (!vma_is_dax(vma))
> 		has_deposit = true;
>
> No need in squeezing it into single line.

Well part of the point here was to avoid ugly:

	Indent
		Indent
			Indent

And that worsens the situation.

Let me think about this again on respin.

>
> --
>   Kiryl Shutsemau / Kirill A. Shutemov

Thanks, Lorenzo
Re: [PATCH v2 7/9] mm/huge_memory: deduplicate zap deposited table call
Posted by Lorenzo Stoakes (Oracle) 2 weeks, 2 days ago
On Fri, Mar 20, 2026 at 02:00:04PM +0000, Lorenzo Stoakes (Oracle) wrote:
> On Thu, Mar 19, 2026 at 09:56:53PM +0000, Kiryl Shutsemau wrote:
> >
> > 	if (!vma_is_dax(vma))
> > 		has_deposit = true;
> >
> > No need in squeezing it into single line.
>
> Well part of the point here was to avoid ugly:
>
> 	Indent
> 		Indent
> 			Indent

Actually it's not too bad let's do that.

Cheers, Lorenzo