Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Sat, Jan 02, 2016 at 12:06:38PM -0500, Matthew Wilcox wrote:
> On Mon, Dec 28, 2015 at 12:05:51PM +0200, Kirill A. Shutemov wrote:
> > On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> > > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > > index 4bf3811..e14634f 100644
> > > --- a/include/linux/mm.h
> > > +++ b/include/linux/mm.h
> > > @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct
> > > mm_struct *mm, pmd_t *pmd)
> > > return ptl;
> > > }
> > >
> > > +/*
> > > + * No scalability reason to split PUD locks yet, but follow the same
> > > pattern
> > > + * as the PMD locks to make it easier if we have to.
> > > + */
> >
> > I don't think it makes any good unless you convert all other places where
> > we use page_table_lock to protect pud table (like __pud_alloc()) to the
> > same API.
> > I think this would deserve separate patch.
>
> Sure, a separate patch to convert existing users of the PTL. But I
> don't think it does any harm to introduce the PUD version of the PMD API.
> Maybe with a comment indicating that tere is significant work to be done
> in converting existing users to this API?
I think that's fine with the fat comment around pud_lock() definition.
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index 416b129..7328df0 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> > > mmu_gather *tlb,
> > > pud = pud_offset(pgd, addr);
> > > do {
> > > next = pud_addr_end(addr, end);
> > > + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> > > + if (next - addr != HPAGE_PUD_SIZE) {
> > > +#ifdef CONFIG_DEBUG_VM
> >
> > IS_ENABLED(CONFIG_DEBUG_VM) ?
> >
> > > + if (!rwsem_is_locked(>mm->mmap_sem)) {
> > > + pr_err("%s: mmap_sem is unlocked!
> > > addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> > > + __func__, addr, end,
> > > + vma->vm_start,
> > > + vma->vm_end);
> >
> > dump_vma(), I guess.
>
> These two issues are copy-and-paste from the existing PMD code. I'm happy
> to update the PMD code to the new-and-improved way of doing things;
> I'm just not keen to have the PMD and PUD code diverge unnecessarily.
Yes, please update PMD too. It looks ugly. VM_BUG_ON_VMA() is probably
right way to deal with this.
--
Kirill A. Shutemov
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Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Sat, Jan 02, 2016 at 12:06:38PM -0500, Matthew Wilcox wrote:
> On Mon, Dec 28, 2015 at 12:05:51PM +0200, Kirill A. Shutemov wrote:
> > On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> > > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > > index 4bf3811..e14634f 100644
> > > --- a/include/linux/mm.h
> > > +++ b/include/linux/mm.h
> > > @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct
> > > mm_struct *mm, pmd_t *pmd)
> > > return ptl;
> > > }
> > >
> > > +/*
> > > + * No scalability reason to split PUD locks yet, but follow the same
> > > pattern
> > > + * as the PMD locks to make it easier if we have to.
> > > + */
> >
> > I don't think it makes any good unless you convert all other places where
> > we use page_table_lock to protect pud table (like __pud_alloc()) to the
> > same API.
> > I think this would deserve separate patch.
>
> Sure, a separate patch to convert existing users of the PTL. But I
> don't think it does any harm to introduce the PUD version of the PMD API.
> Maybe with a comment indicating that tere is significant work to be done
> in converting existing users to this API?
I think that's fine with the fat comment around pud_lock() definition.
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index 416b129..7328df0 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> > > mmu_gather *tlb,
> > > pud = pud_offset(pgd, addr);
> > > do {
> > > next = pud_addr_end(addr, end);
> > > + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> > > + if (next - addr != HPAGE_PUD_SIZE) {
> > > +#ifdef CONFIG_DEBUG_VM
> >
> > IS_ENABLED(CONFIG_DEBUG_VM) ?
> >
> > > + if (!rwsem_is_locked(>mm->mmap_sem)) {
> > > + pr_err("%s: mmap_sem is unlocked!
> > > addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> > > + __func__, addr, end,
> > > + vma->vm_start,
> > > + vma->vm_end);
> >
> > dump_vma(), I guess.
>
> These two issues are copy-and-paste from the existing PMD code. I'm happy
> to update the PMD code to the new-and-improved way of doing things;
> I'm just not keen to have the PMD and PUD code diverge unnecessarily.
Yes, please update PMD too. It looks ugly. VM_BUG_ON_VMA() is probably
right way to deal with this.
--
Kirill A. Shutemov
--
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Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Mon, Dec 28, 2015 at 12:05:51PM +0200, Kirill A. Shutemov wrote:
> On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 4bf3811..e14634f 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct mm_struct
> > *mm, pmd_t *pmd)
> > return ptl;
> > }
> >
> > +/*
> > + * No scalability reason to split PUD locks yet, but follow the same
> > pattern
> > + * as the PMD locks to make it easier if we have to.
> > + */
>
> I don't think it makes any good unless you convert all other places where
> we use page_table_lock to protect pud table (like __pud_alloc()) to the
> same API.
> I think this would deserve separate patch.
Sure, a separate patch to convert existing users of the PTL. But I
don't think it does any harm to introduce the PUD version of the PMD API.
Maybe with a comment indicating that tere is significant work to be done
in converting existing users to this API?
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 416b129..7328df0 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> > mmu_gather *tlb,
> > pud = pud_offset(pgd, addr);
> > do {
> > next = pud_addr_end(addr, end);
> > + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> > + if (next - addr != HPAGE_PUD_SIZE) {
> > +#ifdef CONFIG_DEBUG_VM
>
> IS_ENABLED(CONFIG_DEBUG_VM) ?
>
> > + if (!rwsem_is_locked(>mm->mmap_sem)) {
> > + pr_err("%s: mmap_sem is unlocked!
> > addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> > + __func__, addr, end,
> > + vma->vm_start,
> > + vma->vm_end);
>
> dump_vma(), I guess.
These two issues are copy-and-paste from the existing PMD code. I'm happy
to update the PMD code to the new-and-improved way of doing things;
I'm just not keen to have the PMD and PUD code diverge unnecessarily.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Mon, Dec 28, 2015 at 12:05:51PM +0200, Kirill A. Shutemov wrote:
> On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 4bf3811..e14634f 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct mm_struct
> > *mm, pmd_t *pmd)
> > return ptl;
> > }
> >
> > +/*
> > + * No scalability reason to split PUD locks yet, but follow the same
> > pattern
> > + * as the PMD locks to make it easier if we have to.
> > + */
>
> I don't think it makes any good unless you convert all other places where
> we use page_table_lock to protect pud table (like __pud_alloc()) to the
> same API.
> I think this would deserve separate patch.
Sure, a separate patch to convert existing users of the PTL. But I
don't think it does any harm to introduce the PUD version of the PMD API.
Maybe with a comment indicating that tere is significant work to be done
in converting existing users to this API?
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 416b129..7328df0 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> > mmu_gather *tlb,
> > pud = pud_offset(pgd, addr);
> > do {
> > next = pud_addr_end(addr, end);
> > + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> > + if (next - addr != HPAGE_PUD_SIZE) {
> > +#ifdef CONFIG_DEBUG_VM
>
> IS_ENABLED(CONFIG_DEBUG_VM) ?
>
> > + if (!rwsem_is_locked(>mm->mmap_sem)) {
> > + pr_err("%s: mmap_sem is unlocked!
> > addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> > + __func__, addr, end,
> > + vma->vm_start,
> > + vma->vm_end);
>
> dump_vma(), I guess.
These two issues are copy-and-paste from the existing PMD code. I'm happy
to update the PMD code to the new-and-improved way of doing things;
I'm just not keen to have the PMD and PUD code diverge unnecessarily.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote: > The only major difference is how the new ->pud_entry method in mm_walk > works. The ->pmd_entry method replaces the ->pte_entry method, whereas > the ->pud_entry method works along with either ->pmd_entry or ->pte_entry. I think it makes pagewalk API confusing. We need something more coherent. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 4bf3811..e14634f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct mm_struct
> *mm, pmd_t *pmd)
> return ptl;
> }
>
> +/*
> + * No scalability reason to split PUD locks yet, but follow the same pattern
> + * as the PMD locks to make it easier if we have to.
> + */
I don't think it makes any good unless you convert all other places where
we use page_table_lock to protect pud table (like __pud_alloc()) to the
same API.
I think this would deserve separate patch.
> +static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud)
> +{
> + spinlock_t *ptl = >page_table_lock;
> + spin_lock(ptl);
> + return ptl;
> +}
> +
> extern void free_area_init(unsigned long * zones_size);
> extern void free_area_init_node(int nid, unsigned long * zones_size,
> unsigned long zone_start_pfn, unsigned long *zholes_size);
...
> diff --git a/mm/memory.c b/mm/memory.c
> index 416b129..7328df0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> mmu_gather *tlb,
> pud = pud_offset(pgd, addr);
> do {
> next = pud_addr_end(addr, end);
> + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> + if (next - addr != HPAGE_PUD_SIZE) {
> +#ifdef CONFIG_DEBUG_VM
IS_ENABLED(CONFIG_DEBUG_VM) ?
> + if (!rwsem_is_locked(>mm->mmap_sem)) {
> + pr_err("%s: mmap_sem is unlocked!
> addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> + __func__, addr, end,
> + vma->vm_start,
> + vma->vm_end);
dump_vma(), I guess.
> + BUG();
> + }
> +#endif
> + split_huge_pud(vma, pud, addr);
> + } else if (zap_huge_pud(tlb, vma, pud, addr))
> + goto next;
> + /* fall through */
> + }
> if (pud_none_or_clear_bad(pud))
> continue;
> next = zap_pmd_range(tlb, vma, pud, addr, next, details);
> +next:
> + cond_resched();
> } while (pud++, addr = next, addr != end);
>
> return addr;
--
Kirill A. Shutemov
--
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote:
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 4bf3811..e14634f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1958,6 +1977,17 @@ static inline spinlock_t *pmd_lock(struct mm_struct
> *mm, pmd_t *pmd)
> return ptl;
> }
>
> +/*
> + * No scalability reason to split PUD locks yet, but follow the same pattern
> + * as the PMD locks to make it easier if we have to.
> + */
I don't think it makes any good unless you convert all other places where
we use page_table_lock to protect pud table (like __pud_alloc()) to the
same API.
I think this would deserve separate patch.
> +static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud)
> +{
> + spinlock_t *ptl = >page_table_lock;
> + spin_lock(ptl);
> + return ptl;
> +}
> +
> extern void free_area_init(unsigned long * zones_size);
> extern void free_area_init_node(int nid, unsigned long * zones_size,
> unsigned long zone_start_pfn, unsigned long *zholes_size);
...
> diff --git a/mm/memory.c b/mm/memory.c
> index 416b129..7328df0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1220,9 +1220,27 @@ static inline unsigned long zap_pud_range(struct
> mmu_gather *tlb,
> pud = pud_offset(pgd, addr);
> do {
> next = pud_addr_end(addr, end);
> + if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
> + if (next - addr != HPAGE_PUD_SIZE) {
> +#ifdef CONFIG_DEBUG_VM
IS_ENABLED(CONFIG_DEBUG_VM) ?
> + if (!rwsem_is_locked(>mm->mmap_sem)) {
> + pr_err("%s: mmap_sem is unlocked!
> addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
> + __func__, addr, end,
> + vma->vm_start,
> + vma->vm_end);
dump_vma(), I guess.
> + BUG();
> + }
> +#endif
> + split_huge_pud(vma, pud, addr);
> + } else if (zap_huge_pud(tlb, vma, pud, addr))
> + goto next;
> + /* fall through */
> + }
> if (pud_none_or_clear_bad(pud))
> continue;
> next = zap_pmd_range(tlb, vma, pud, addr, next, details);
> +next:
> + cond_resched();
> } while (pud++, addr = next, addr != end);
>
> return addr;
--
Kirill A. Shutemov
--
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/8] mm: Add optional support for PUD-sized transparent hugepages
On Thu, Dec 24, 2015 at 11:20:30AM -0500, Matthew Wilcox wrote: > The only major difference is how the new ->pud_entry method in mm_walk > works. The ->pmd_entry method replaces the ->pte_entry method, whereas > the ->pud_entry method works along with either ->pmd_entry or ->pte_entry. I think it makes pagewalk API confusing. We need something more coherent. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
