2022-06-24 18:00:48

by James Houghton

Subject: [RFC PATCH 06/26] mm: make free_p?d_range functions public

This makes them usable for HugeTLB page table freeing operations.
After HugeTLB high-granularity mapping, the page table for a HugeTLB VMA
can get more complex, and these functions handle freeing page tables
generally.

Signed-off-by: James Houghton <[email protected]>
---
include/linux/mm.h | 7 +++++++
mm/memory.c | 8 ++++----
2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc8f326be0ce..07f5da512147 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1847,6 +1847,13 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,

struct mmu_notifier_range;

+void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr);
+void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, unsigned long addr,
+ unsigned long end, unsigned long floor, unsigned long ceiling);
+void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, unsigned long addr,
+ unsigned long end, unsigned long floor, unsigned long ceiling);
+void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, unsigned long addr,
+ unsigned long end, unsigned long floor, unsigned long ceiling);
void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
int
diff --git a/mm/memory.c b/mm/memory.c
index 7a089145cad4..bb3b9b5b94fb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -227,7 +227,7 @@ static void check_sync_rss_stat(struct task_struct *task)
* Note: this doesn't free the actual pages themselves. That
* has been handled earlier when unmapping all the memory regions.
*/
-static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
+void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
unsigned long addr)
{
pgtable_t token = pmd_pgtable(*pmd);
@@ -236,7 +236,7 @@ static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
mm_dec_nr_ptes(tlb->mm);
}

-static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
@@ -270,7 +270,7 @@ static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
mm_dec_nr_pmds(tlb->mm);
}

-static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
+inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
@@ -304,7 +304,7 @@ static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
mm_dec_nr_puds(tlb->mm);
}

-static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
+inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
--
2.37.0.rc0.161.g10f37bed90-goog

2022-06-27 12:37:40

by manish.mishra

Subject: Re: [RFC PATCH 06/26] mm: make free_p?d_range functions public

On 24/06/22 11:06 pm, James Houghton wrote:
> This makes them usable for HugeTLB page table freeing operations.
> After HugeTLB high-granularity mapping, the page table for a HugeTLB VMA
> can get more complex, and these functions handle freeing page tables
> generally.
>
> Signed-off-by: James Houghton <[email protected]>
reviewed-by: [email protected]
> ---
> include/linux/mm.h | 7 +++++++
> mm/memory.c | 8 ++++----
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index bc8f326be0ce..07f5da512147 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1847,6 +1847,13 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
>
> struct mmu_notifier_range;
>
> +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr);
> +void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> +void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> +void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
> unsigned long end, unsigned long floor, unsigned long ceiling);
> int
> diff --git a/mm/memory.c b/mm/memory.c
> index 7a089145cad4..bb3b9b5b94fb 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -227,7 +227,7 @@ static void check_sync_rss_stat(struct task_struct *task)
> * Note: this doesn't free the actual pages themselves. That
> * has been handled earlier when unmapping all the memory regions.
> */
> -static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> unsigned long addr)
> {
> pgtable_t token = pmd_pgtable(*pmd);
> @@ -236,7 +236,7 @@ static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> mm_dec_nr_ptes(tlb->mm);
> }
>
> -static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> +inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {
> @@ -270,7 +270,7 @@ static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> mm_dec_nr_pmds(tlb->mm);
> }
>
> -static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> +inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {
> @@ -304,7 +304,7 @@ static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> mm_dec_nr_puds(tlb->mm);
> }
>
> -static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> +inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {

2022-06-28 20:48:26

by Mike Kravetz

Subject: Re: [RFC PATCH 06/26] mm: make free_p?d_range functions public

On 06/24/22 17:36, James Houghton wrote:
> This makes them usable for HugeTLB page table freeing operations.
> After HugeTLB high-granularity mapping, the page table for a HugeTLB VMA
> can get more complex, and these functions handle freeing page tables
> generally.
>

Hmmmm?

free_pgd_range is not generally called directly for hugetlb mappings.
There is a wrapper hugetlb_free_pgd_range which can have architecture
specific implementations. It makes me wonder if these lower level
routines can be directly used on hugetlb mappings. My 'guess' is that any
such details will be hidden in the callers. Suspect this will become clear
in later patches.
--
Mike Kravetz

> Signed-off-by: James Houghton <[email protected]>
> ---
> include/linux/mm.h | 7 +++++++
> mm/memory.c | 8 ++++----
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index bc8f326be0ce..07f5da512147 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1847,6 +1847,13 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
>
> struct mmu_notifier_range;
>
> +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr);
> +void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> +void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> +void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, unsigned long addr,
> + unsigned long end, unsigned long floor, unsigned long ceiling);
> void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
> unsigned long end, unsigned long floor, unsigned long ceiling);
> int
> diff --git a/mm/memory.c b/mm/memory.c
> index 7a089145cad4..bb3b9b5b94fb 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -227,7 +227,7 @@ static void check_sync_rss_stat(struct task_struct *task)
> * Note: this doesn't free the actual pages themselves. That
> * has been handled earlier when unmapping all the memory regions.
> */
> -static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> unsigned long addr)
> {
> pgtable_t token = pmd_pgtable(*pmd);
> @@ -236,7 +236,7 @@ static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> mm_dec_nr_ptes(tlb->mm);
> }
>
> -static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> +inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {
> @@ -270,7 +270,7 @@ static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> mm_dec_nr_pmds(tlb->mm);
> }
>
> -static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> +inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {
> @@ -304,7 +304,7 @@ static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> mm_dec_nr_puds(tlb->mm);
> }
>
> -static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> +inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> unsigned long addr, unsigned long end,
> unsigned long floor, unsigned long ceiling)
> {
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>

2022-07-12 20:55:53

by James Houghton

Subject: Re: [RFC PATCH 06/26] mm: make free_p?d_range functions public

On Tue, Jun 28, 2022 at 1:35 PM Mike Kravetz <[email protected]> wrote:
>
> On 06/24/22 17:36, James Houghton wrote:
> > This makes them usable for HugeTLB page table freeing operations.
> > After HugeTLB high-granularity mapping, the page table for a HugeTLB VMA
> > can get more complex, and these functions handle freeing page tables
> > generally.
> >
>
> Hmmmm?
>
> free_pgd_range is not generally called directly for hugetlb mappings.
> There is a wrapper hugetlb_free_pgd_range which can have architecture
> specific implementations. It makes me wonder if these lower level
> routines can be directly used on hugetlb mappings. My 'guess' is that any
> such details will be hidden in the callers. Suspect this will become clear
> in later patches.

Thanks for pointing out hugetlb_free_pgd_range. I think I'll need to
change how freeing HugeTLB HGM PTEs is written, because as written, we
don't do any architecture-specific things. I think I have a good idea
for what I need to do, probably something like this: make
`hugetlb_free_range` overridable, and then provide an implementation
for it for all the architectures that
HAVE_ARCH_HUGETLB_FREE_PGD_RANGE. Making the regular `free_p?d_range`
functions public *does* help with implementing the regular/general
`hugetlb_free_range` function though, so I think this commit is still
useful.

- James

> --
> Mike Kravetz
>
> > Signed-off-by: James Houghton <[email protected]>
> > ---
> > include/linux/mm.h | 7 +++++++
> > mm/memory.c | 8 ++++----
> > 2 files changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index bc8f326be0ce..07f5da512147 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -1847,6 +1847,13 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
> >
> > struct mmu_notifier_range;
> >
> > +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr);
> > +void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, unsigned long addr,
> > + unsigned long end, unsigned long floor, unsigned long ceiling);
> > +void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, unsigned long addr,
> > + unsigned long end, unsigned long floor, unsigned long ceiling);
> > +void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, unsigned long addr,
> > + unsigned long end, unsigned long floor, unsigned long ceiling);
> > void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
> > unsigned long end, unsigned long floor, unsigned long ceiling);
> > int
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 7a089145cad4..bb3b9b5b94fb 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -227,7 +227,7 @@ static void check_sync_rss_stat(struct task_struct *task)
> > * Note: this doesn't free the actual pages themselves. That
> > * has been handled earlier when unmapping all the memory regions.
> > */
> > -static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> > +void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> > unsigned long addr)
> > {
> > pgtable_t token = pmd_pgtable(*pmd);
> > @@ -236,7 +236,7 @@ static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
> > mm_dec_nr_ptes(tlb->mm);
> > }
> >
> > -static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> > +inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> > unsigned long addr, unsigned long end,
> > unsigned long floor, unsigned long ceiling)
> > {
> > @@ -270,7 +270,7 @@ static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> > mm_dec_nr_pmds(tlb->mm);
> > }
> >
> > -static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> > +inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> > unsigned long addr, unsigned long end,
> > unsigned long floor, unsigned long ceiling)
> > {
> > @@ -304,7 +304,7 @@ static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
> > mm_dec_nr_puds(tlb->mm);
> > }
> >
> > -static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> > +inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
> > unsigned long addr, unsigned long end,
> > unsigned long floor, unsigned long ceiling)
> > {
> > --
> > 2.37.0.rc0.161.g10f37bed90-goog
> >