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* Re: [RFC 1/7] mm: introduce MADV_COOL
@ 2019-05-28 12:15 Hillf Danton
  2019-05-28 12:39 ` Minchan Kim
  0 siblings, 1 reply; 18+ messages in thread
From: Hillf Danton @ 2019-05-28 12:15 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon


On Tue, 28 May 2019 18:58:15 +0800 Minchan Kim wrote:
> On Tue, May 28, 2019 at 04:53:01PM +0800, Hillf Danton wrote:
> >
> > On Mon, 20 May 2019 12:52:48 +0900 Minchan Kim wrote:
> > > +static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr,
> > > +				unsigned long end, struct mm_walk *walk)
> > > +{
> > > +	pte_t *orig_pte, *pte, ptent;
> > > +	spinlock_t *ptl;
> > > +	struct page *page;
> > > +	struct vm_area_struct *vma = walk->vma;
> > > +	unsigned long next;
> > > +
> > > +	next = pmd_addr_end(addr, end);
> > > +	if (pmd_trans_huge(*pmd)) {
> > > +		spinlock_t *ptl;
> >
> > Seems not needed with another ptl declared above.
>
> Will remove it.
>
> > > +
> > > +		ptl = pmd_trans_huge_lock(pmd, vma);
> > > +		if (!ptl)
> > > +			return 0;
> > > +
> > > +		if (is_huge_zero_pmd(*pmd))
> > > +			goto huge_unlock;
> > > +
> > > +		page = pmd_page(*pmd);
> > > +		if (page_mapcount(page) > 1)
> > > +			goto huge_unlock;
> > > +
> > > +		if (next - addr != HPAGE_PMD_SIZE) {
> > > +			int err;
> >
> > Alternately, we deactivate thp only if the address range from userspace
> > is sane enough, in order to avoid complex works we have to do here.
>
> Not sure it's a good idea. That's the way we have done in MADV_FREE
> so want to be consistent.
>
Fair.

> > > +
> > > +			get_page(page);
> > > +			spin_unlock(ptl);
> > > +			lock_page(page);
> > > +			err = split_huge_page(page);
> > > +			unlock_page(page);
> > > +			put_page(page);
> > > +			if (!err)
> > > +				goto regular_page;
> > > +			return 0;
> > > +		}
> > > +
> > > +		pmdp_test_and_clear_young(vma, addr, pmd);
> > > +		deactivate_page(page);
> > > +huge_unlock:
> > > +		spin_unlock(ptl);
> > > +		return 0;
> > > +	}
> > > +
> > > +	if (pmd_trans_unstable(pmd))
> > > +		return 0;
> > > +
> > > +regular_page:
> >
> > Take a look at pending signal?
>
> Do you have any reason to see pending signal here? I want to know what's
> your requirement so that what's the better place to handle it.
>
We could bail out without work done IMO if there is a fatal siganl pending.
And we can do that, if it makes sense to you, before the hard work.

> >
> > > +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> > > +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
> >
> > s/end/next/ ?
>
> Why do you think it should be next?
>
Simply based on the following line, and afraid that next != end
	> > > +	next = pmd_addr_end(addr, end);

> > > +		ptent = *pte;
> > > +
> > > +		if (pte_none(ptent))
> > > +			continue;
> > > +
> > > +		if (!pte_present(ptent))
> > > +			continue;
> > > +
> > > +		page = vm_normal_page(vma, addr, ptent);
> > > +		if (!page)
> > > +			continue;
> > > +
> > > +		if (page_mapcount(page) > 1)
> > > +			continue;
> > > +
> > > +		ptep_test_and_clear_young(vma, addr, pte);
> > > +		deactivate_page(page);
> > > +	}
> > > +
> > > +	pte_unmap_unlock(orig_pte, ptl);
> > > +	cond_resched();
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static long madvise_cool(struct vm_area_struct *vma,
> > > +			unsigned long start_addr, unsigned long end_addr)
> > > +{
> > > +	struct mm_struct *mm = vma->vm_mm;
> > > +	struct mmu_gather tlb;
> > > +
> > > +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > > +		return -EINVAL;
> >
> > No service in case of VM_IO?
>
> I don't know VM_IO would have regular LRU pages but just follow normal
> convention for DONTNEED and FREE.
> Do you have anything in your mind?
>
I want to skip a mapping set up for DMA.

BR
Hillf


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-28 12:15 [RFC 1/7] mm: introduce MADV_COOL Hillf Danton
@ 2019-05-28 12:39 ` Minchan Kim
  0 siblings, 0 replies; 18+ messages in thread
From: Minchan Kim @ 2019-05-28 12:39 UTC (permalink / raw)
  To: Hillf Danton
  Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon

On Tue, May 28, 2019 at 08:15:23PM +0800, Hillf Danton wrote:
< snip >
> > > > +
> > > > +			get_page(page);
> > > > +			spin_unlock(ptl);
> > > > +			lock_page(page);
> > > > +			err = split_huge_page(page);
> > > > +			unlock_page(page);
> > > > +			put_page(page);
> > > > +			if (!err)
> > > > +				goto regular_page;
> > > > +			return 0;
> > > > +		}
> > > > +
> > > > +		pmdp_test_and_clear_young(vma, addr, pmd);
> > > > +		deactivate_page(page);
> > > > +huge_unlock:
> > > > +		spin_unlock(ptl);
> > > > +		return 0;
> > > > +	}
> > > > +
> > > > +	if (pmd_trans_unstable(pmd))
> > > > +		return 0;
> > > > +
> > > > +regular_page:
> > >
> > > Take a look at pending signal?
> >
> > Do you have any reason to see pending signal here? I want to know what's
> > your requirement so that what's the better place to handle it.
> >
> We could bail out without work done IMO if there is a fatal siganl pending.
> And we can do that, if it makes sense to you, before the hard work.

Make sense, especically, swapping out.
I will add it in next revision.

> 
> > >
> > > > +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> > > > +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
> > >
> > > s/end/next/ ?
> >
> > Why do you think it should be next?
> >
> Simply based on the following line, and afraid that next != end
> 	> > > +	next = pmd_addr_end(addr, end);

pmd_addr_end will return smaller address so end is more proper.

> 
> > > > +		ptent = *pte;
> > > > +
> > > > +		if (pte_none(ptent))
> > > > +			continue;
> > > > +
> > > > +		if (!pte_present(ptent))
> > > > +			continue;
> > > > +
> > > > +		page = vm_normal_page(vma, addr, ptent);
> > > > +		if (!page)
> > > > +			continue;
> > > > +
> > > > +		if (page_mapcount(page) > 1)
> > > > +			continue;
> > > > +
> > > > +		ptep_test_and_clear_young(vma, addr, pte);
> > > > +		deactivate_page(page);
> > > > +	}
> > > > +
> > > > +	pte_unmap_unlock(orig_pte, ptl);
> > > > +	cond_resched();
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +static long madvise_cool(struct vm_area_struct *vma,
> > > > +			unsigned long start_addr, unsigned long end_addr)
> > > > +{
> > > > +	struct mm_struct *mm = vma->vm_mm;
> > > > +	struct mmu_gather tlb;
> > > > +
> > > > +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > > > +		return -EINVAL;
> > >
> > > No service in case of VM_IO?
> >
> > I don't know VM_IO would have regular LRU pages but just follow normal
> > convention for DONTNEED and FREE.
> > Do you have anything in your mind?
> >
> I want to skip a mapping set up for DMA.

What you meant is those pages in VM_IO vma are not in LRU list?
Or
pages in the vma are always pinned so no worth to deactivate or reclaim?


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
@ 2019-05-29  8:52 Hillf Danton
  0 siblings, 0 replies; 18+ messages in thread
From: Hillf Danton @ 2019-05-29  8:52 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon


On Wed, 29 May 2019 13:05:52 +0800 Michal Hocko wrote:
> On Wed 29-05-19 10:40:33, Hillf Danton wrote:
> > On Wed, 29 May 2019 00:11:15 +0800 Michal Hocko wrote:
> > > On Tue 28-05-19 23:38:11, Hillf Danton wrote:
> > > > 
> > > > In short, I prefer to skip IO mapping since any kind of address range
> > > > can be expected from userspace, and it may probably cover an IO mapping.
> > > > And things can get out of control, if we reclaim some IO pages while
> > > > underlying device is trying to fill data into any of them, for instance.
> > > 
> > > What do you mean by IO pages why what is the actual problem?
> > > 
> > Io pages are the backing-store pages of a mapping whose vm_flags has
> > VM_IO set, and the comment in mm/memory.c says:
> >         /*
> >          * Physically remapped pages are special. Tell the
> >          * rest of the world about it:
> >          *   VM_IO tells people not to look at these pages
> >          *      (accesses can have side effects).
> > 
> 
> OK, thanks for the clarification of the first part of the question. Now
> to the second and the more important one. What is the actual concern?
> AFAIK those pages shouldn't be on LRU list.

The backing pages for GEM object are lru pages, see the function
drm_gem_get_pages() in drivers/gpu/drm/drm_gem.c, please.

> If they are then they should
> be safe to get reclaimed otherwise we would have a problem when
> reclaiming them on the normal memory pressure.

Yes, Sir, they could be swapped out.

> Why is this madvise any different?

Now, it is not, thanks to the light you are casting.

BR
Hillf


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-29  2:40 Hillf Danton
@ 2019-05-29  5:05 ` Michal Hocko
  0 siblings, 0 replies; 18+ messages in thread
From: Michal Hocko @ 2019-05-29  5:05 UTC (permalink / raw)
  To: Hillf Danton
  Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon

On Wed 29-05-19 10:40:33, Hillf Danton wrote:
> 
> On Wed, 29 May 2019 00:11:15 +0800 Michal Hocko wrote:
> > On Tue 28-05-19 23:38:11, Hillf Danton wrote:
> > > 
> > > In short, I prefer to skip IO mapping since any kind of address range
> > > can be expected from userspace, and it may probably cover an IO mapping.
> > > And things can get out of control, if we reclaim some IO pages while
> > > underlying device is trying to fill data into any of them, for instance.
> > 
> > What do you mean by IO pages why what is the actual problem?
> > 
> Io pages are the backing-store pages of a mapping whose vm_flags has
> VM_IO set, and the comment in mm/memory.c says:
>         /*
>          * Physically remapped pages are special. Tell the
>          * rest of the world about it:
>          *   VM_IO tells people not to look at these pages
>          *      (accesses can have side effects).
> 

OK, thanks for the clarification of the first part of the question. Now
to the second and the more important one. What is the actual concern?
AFAIK those pages shouldn't be on LRU list. If they are then they should
be safe to get reclaimed otherwise we would have a problem when
reclaiming them on the normal memory pressure. Why is this madvise any
different?
-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
@ 2019-05-29  2:40 Hillf Danton
  2019-05-29  5:05 ` Michal Hocko
  0 siblings, 1 reply; 18+ messages in thread
From: Hillf Danton @ 2019-05-29  2:40 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon


On Wed, 29 May 2019 00:11:15 +0800 Michal Hocko wrote:
> On Tue 28-05-19 23:38:11, Hillf Danton wrote:
> > 
> > In short, I prefer to skip IO mapping since any kind of address range
> > can be expected from userspace, and it may probably cover an IO mapping.
> > And things can get out of control, if we reclaim some IO pages while
> > underlying device is trying to fill data into any of them, for instance.
> 
> What do you mean by IO pages why what is the actual problem?
> 
Io pages are the backing-store pages of a mapping whose vm_flags has
VM_IO set, and the comment in mm/memory.c says:
        /*
         * Physically remapped pages are special. Tell the
         * rest of the world about it:
         *   VM_IO tells people not to look at these pages
         *      (accesses can have side effects).

BR
Hillf


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-28 15:38 Hillf Danton
@ 2019-05-28 16:11 ` Michal Hocko
  0 siblings, 0 replies; 18+ messages in thread
From: Michal Hocko @ 2019-05-28 16:11 UTC (permalink / raw)
  To: Hillf Danton
  Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon

On Tue 28-05-19 23:38:11, Hillf Danton wrote:
> 
> On Tue, 28 May 2019 20:39:36 +0800 Minchan Kim wrote:
> > On Tue, May 28, 2019 at 08:15:23PM +0800, Hillf Danton wrote:
> > < snip >
> > > > > > +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> > > > > > +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
> > > > >
> > > > > s/end/next/ ?
> > > >
> > > > Why do you think it should be next?
> > > >
> > > Simply based on the following line, and afraid that next != end
> > > 	> > > +	next = pmd_addr_end(addr, end);
> > 
> > pmd_addr_end will return smaller address so end is more proper.
> > 
> Fair.
> 
> > > > > > +static long madvise_cool(struct vm_area_struct *vma,
> > > > > > +			unsigned long start_addr, unsigned long end_addr)
> > > > > > +{
> > > > > > +	struct mm_struct *mm = vma->vm_mm;
> > > > > > +	struct mmu_gather tlb;
> > > > > > +
> > > > > > +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > > > > > +		return -EINVAL;
> > > > >
> > > > > No service in case of VM_IO?
> > > >
> > > > I don't know VM_IO would have regular LRU pages but just follow normal
> > > > convention for DONTNEED and FREE.
> > > > Do you have anything in your mind?
> > > >
> > > I want to skip a mapping set up for DMA.
> > 
> > What you meant is those pages in VM_IO vma are not in LRU list?
> 
> What I concern is the case that there are IO pages on lru list.
> > Or
> > pages in the vma are always pinned so no worth to deactivate or reclaim?
> > 
> I will not be nervous or paranoid if they are pinned.
> 
> In short, I prefer to skip IO mapping since any kind of address range
> can be expected from userspace, and it may probably cover an IO mapping.
> And things can get out of control, if we reclaim some IO pages while
> underlying device is trying to fill data into any of them, for instance.

What do you mean by IO pages why what is the actual problem?
-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
@ 2019-05-28 15:38 Hillf Danton
  2019-05-28 16:11 ` Michal Hocko
  0 siblings, 1 reply; 18+ messages in thread
From: Hillf Danton @ 2019-05-28 15:38 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon


On Tue, 28 May 2019 20:39:36 +0800 Minchan Kim wrote:
> On Tue, May 28, 2019 at 08:15:23PM +0800, Hillf Danton wrote:
> < snip >
> > > > > +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> > > > > +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
> > > >
> > > > s/end/next/ ?
> > >
> > > Why do you think it should be next?
> > >
> > Simply based on the following line, and afraid that next != end
> > 	> > > +	next = pmd_addr_end(addr, end);
> 
> pmd_addr_end will return smaller address so end is more proper.
> 
Fair.

> > > > > +static long madvise_cool(struct vm_area_struct *vma,
> > > > > +			unsigned long start_addr, unsigned long end_addr)
> > > > > +{
> > > > > +	struct mm_struct *mm = vma->vm_mm;
> > > > > +	struct mmu_gather tlb;
> > > > > +
> > > > > +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > > > > +		return -EINVAL;
> > > >
> > > > No service in case of VM_IO?
> > >
> > > I don't know VM_IO would have regular LRU pages but just follow normal
> > > convention for DONTNEED and FREE.
> > > Do you have anything in your mind?
> > >
> > I want to skip a mapping set up for DMA.
> 
> What you meant is those pages in VM_IO vma are not in LRU list?

What I concern is the case that there are IO pages on lru list.
> Or
> pages in the vma are always pinned so no worth to deactivate or reclaim?
> 
I will not be nervous or paranoid if they are pinned.

In short, I prefer to skip IO mapping since any kind of address range
can be expected from userspace, and it may probably cover an IO mapping.
And things can get out of control, if we reclaim some IO pages while
underlying device is trying to fill data into any of them, for instance.

BR
Hillf


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim
  2019-05-20  8:16   ` Michal Hocko
  2019-05-28  8:53   ` Hillf Danton
@ 2019-05-28 10:58   ` Minchan Kim
  2 siblings, 0 replies; 18+ messages in thread
From: Minchan Kim @ 2019-05-28 10:58 UTC (permalink / raw)
  To: Hillf Danton
  Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon

On Tue, May 28, 2019 at 04:53:01PM +0800, Hillf Danton wrote:
> 
> On Mon, 20 May 2019 12:52:48 +0900 Minchan Kim wrote:
> > +static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr,
> > +				unsigned long end, struct mm_walk *walk)
> > +{
> > +	pte_t *orig_pte, *pte, ptent;
> > +	spinlock_t *ptl;
> > +	struct page *page;
> > +	struct vm_area_struct *vma = walk->vma;
> > +	unsigned long next;
> > +
> > +	next = pmd_addr_end(addr, end);
> > +	if (pmd_trans_huge(*pmd)) {
> > +		spinlock_t *ptl;
> 
> Seems not needed with another ptl declared above.

Will remove it.

> > +
> > +		ptl = pmd_trans_huge_lock(pmd, vma);
> > +		if (!ptl)
> > +			return 0;
> > +
> > +		if (is_huge_zero_pmd(*pmd))
> > +			goto huge_unlock;
> > +
> > +		page = pmd_page(*pmd);
> > +		if (page_mapcount(page) > 1)
> > +			goto huge_unlock;
> > +
> > +		if (next - addr != HPAGE_PMD_SIZE) {
> > +			int err;
> 
> Alternately, we deactivate thp only if the address range from userspace
> is sane enough, in order to avoid complex works we have to do here.

Not sure it's a good idea. That's the way we have done in MADV_FREE
so want to be consistent.

> > +
> > +			get_page(page);
> > +			spin_unlock(ptl);
> > +			lock_page(page);
> > +			err = split_huge_page(page);
> > +			unlock_page(page);
> > +			put_page(page);
> > +			if (!err)
> > +				goto regular_page;
> > +			return 0;
> > +		}
> > +
> > +		pmdp_test_and_clear_young(vma, addr, pmd);
> > +		deactivate_page(page);
> > +huge_unlock:
> > +		spin_unlock(ptl);
> > +		return 0;
> > +	}
> > +
> > +	if (pmd_trans_unstable(pmd))
> > +		return 0;
> > +
> > +regular_page:
> 
> Take a look at pending signal?

Do you have any reason to see pending signal here? I want to know what's
your requirement so that what's the better place to handle it.

> 
> > +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> > +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
> 
> s/end/next/ ?

Why do you think it should be next?

> > +		ptent = *pte;
> > +
> > +		if (pte_none(ptent))
> > +			continue;
> > +
> > +		if (!pte_present(ptent))
> > +			continue;
> > +
> > +		page = vm_normal_page(vma, addr, ptent);
> > +		if (!page)
> > +			continue;
> > +
> > +		if (page_mapcount(page) > 1)
> > +			continue;
> > +
> > +		ptep_test_and_clear_young(vma, addr, pte);
> > +		deactivate_page(page);
> > +	}
> > +
> > +	pte_unmap_unlock(orig_pte, ptl);
> > +	cond_resched();
> > +
> > +	return 0;
> > +}
> > +
> > +static long madvise_cool(struct vm_area_struct *vma,
> > +			unsigned long start_addr, unsigned long end_addr)
> > +{
> > +	struct mm_struct *mm = vma->vm_mm;
> > +	struct mmu_gather tlb;
> > +
> > +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > +		return -EINVAL;
> 
> No service in case of VM_IO?

I don't know VM_IO would have regular LRU pages but just follow normal
convention for DONTNEED and FREE.
Do you have anything in your mind?


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim
  2019-05-20  8:16   ` Michal Hocko
@ 2019-05-28  8:53   ` Hillf Danton
  2019-05-28 10:58   ` Minchan Kim
  2 siblings, 0 replies; 18+ messages in thread
From: Hillf Danton @ 2019-05-28  8:53 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner,
	Tim Murray, Joel Fernandes, Suren Baghdasaryan,
	Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon


On Mon, 20 May 2019 12:52:48 +0900 Minchan Kim wrote:
> +static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr,
> +				unsigned long end, struct mm_walk *walk)
> +{
> +	pte_t *orig_pte, *pte, ptent;
> +	spinlock_t *ptl;
> +	struct page *page;
> +	struct vm_area_struct *vma = walk->vma;
> +	unsigned long next;
> +
> +	next = pmd_addr_end(addr, end);
> +	if (pmd_trans_huge(*pmd)) {
> +		spinlock_t *ptl;

Seems not needed with another ptl declared above.
> +
> +		ptl = pmd_trans_huge_lock(pmd, vma);
> +		if (!ptl)
> +			return 0;
> +
> +		if (is_huge_zero_pmd(*pmd))
> +			goto huge_unlock;
> +
> +		page = pmd_page(*pmd);
> +		if (page_mapcount(page) > 1)
> +			goto huge_unlock;
> +
> +		if (next - addr != HPAGE_PMD_SIZE) {
> +			int err;

Alternately, we deactivate thp only if the address range from userspace
is sane enough, in order to avoid complex works we have to do here.
> +
> +			get_page(page);
> +			spin_unlock(ptl);
> +			lock_page(page);
> +			err = split_huge_page(page);
> +			unlock_page(page);
> +			put_page(page);
> +			if (!err)
> +				goto regular_page;
> +			return 0;
> +		}
> +
> +		pmdp_test_and_clear_young(vma, addr, pmd);
> +		deactivate_page(page);
> +huge_unlock:
> +		spin_unlock(ptl);
> +		return 0;
> +	}
> +
> +	if (pmd_trans_unstable(pmd))
> +		return 0;
> +
> +regular_page:

Take a look at pending signal?

> +	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
> +	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {

s/end/next/ ?
> +		ptent = *pte;
> +
> +		if (pte_none(ptent))
> +			continue;
> +
> +		if (!pte_present(ptent))
> +			continue;
> +
> +		page = vm_normal_page(vma, addr, ptent);
> +		if (!page)
> +			continue;
> +
> +		if (page_mapcount(page) > 1)
> +			continue;
> +
> +		ptep_test_and_clear_young(vma, addr, pte);
> +		deactivate_page(page);
> +	}
> +
> +	pte_unmap_unlock(orig_pte, ptl);
> +	cond_resched();
> +
> +	return 0;
> +}
> +
> +static long madvise_cool(struct vm_area_struct *vma,
> +			unsigned long start_addr, unsigned long end_addr)
> +{
> +	struct mm_struct *mm = vma->vm_mm;
> +	struct mmu_gather tlb;
> +
> +	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> +		return -EINVAL;

No service in case of VM_IO?
> +
> +	lru_add_drain();
> +	tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
> +	madvise_cool_page_range(&tlb, vma, start_addr, end_addr);
> +	tlb_finish_mmu(&tlb, start_addr, end_addr);
> +
> +	return 0;
> +}
> +
> +/*
> + * deactivate_page - deactivate a page
> + * @page: page to deactivate
> + *
> + * deactivate_page() moves @page to the inactive list if @page was on the active
> + * list and was not an unevictable page.  This is done to accelerate the reclaim
> + * of @page.
> + */
> +void deactivate_page(struct page *page)
> +{
> +	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
> +		struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
> +
> +		get_page(page);

A line of comment seems needed for pinning the page.

> +		if (!pagevec_add(pvec, page) || PageCompound(page))
> +			pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
> +		put_cpu_var(lru_deactivate_pvecs);
> +	}
> +}
> +

--
Hillf


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-21  9:11         ` Minchan Kim
@ 2019-05-21 10:05           ` Michal Hocko
  0 siblings, 0 replies; 18+ messages in thread
From: Michal Hocko @ 2019-05-21 10:05 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Tue 21-05-19 18:11:34, Minchan Kim wrote:
> On Tue, May 21, 2019 at 08:04:43AM +0200, Michal Hocko wrote:
> > On Tue 21-05-19 07:54:19, Minchan Kim wrote:
> > > On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote:
> > [...]
> > > > > Internally, it works via deactivating memory from active list to
> > > > > inactive's head so when the memory pressure happens, they will be
> > > > > reclaimed earlier than other active pages unless there is no
> > > > > access until the time.
> > > > 
> > > > Could you elaborate about the decision to move to the head rather than
> > > > tail? What should happen to inactive pages? Should we move them to the
> > > > tail? Your implementation seems to ignore those completely. Why?
> > > 
> > > Normally, inactive LRU could have used-once pages without any mapping
> > > to user's address space. Such pages would be better candicate to
> > > reclaim when the memory pressure happens. With deactivating only
> > > active LRU pages of the process to the head of inactive LRU, we will
> > > keep them in RAM longer than used-once pages and could have more chance
> > > to be activated once the process is resumed.
> > 
> > You are making some assumptions here. You have an explicit call what is
> > cold now you are assuming something is even colder. Is this assumption a
> > general enough to make people depend on it? Not that we wouldn't be able
> > to change to logic later but that will always be risky - especially in
> > the area when somebody want to make a user space driven memory
> > management.
> 
> Think about MADV_FREE. It moves those pages into inactive file LRU's head.
> See the get_scan_count which makes forceful scanning of inactive file LRU
> if it has enough size based on the memory pressure.
> The reason is it's likely to have used-once pages in inactive file LRU,
> generally. Those pages has been top-priority candidate to be reclaimed
> for a long time.

OK, fair enough. Being consistent with MADV_FREE is reasonable. I just
forgot we do rotate like this there.

-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-21  6:04       ` Michal Hocko
@ 2019-05-21  9:11         ` Minchan Kim
  2019-05-21 10:05           ` Michal Hocko
  0 siblings, 1 reply; 18+ messages in thread
From: Minchan Kim @ 2019-05-21  9:11 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Tue, May 21, 2019 at 08:04:43AM +0200, Michal Hocko wrote:
> On Tue 21-05-19 07:54:19, Minchan Kim wrote:
> > On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote:
> [...]
> > > > Internally, it works via deactivating memory from active list to
> > > > inactive's head so when the memory pressure happens, they will be
> > > > reclaimed earlier than other active pages unless there is no
> > > > access until the time.
> > > 
> > > Could you elaborate about the decision to move to the head rather than
> > > tail? What should happen to inactive pages? Should we move them to the
> > > tail? Your implementation seems to ignore those completely. Why?
> > 
> > Normally, inactive LRU could have used-once pages without any mapping
> > to user's address space. Such pages would be better candicate to
> > reclaim when the memory pressure happens. With deactivating only
> > active LRU pages of the process to the head of inactive LRU, we will
> > keep them in RAM longer than used-once pages and could have more chance
> > to be activated once the process is resumed.
> 
> You are making some assumptions here. You have an explicit call what is
> cold now you are assuming something is even colder. Is this assumption a
> general enough to make people depend on it? Not that we wouldn't be able
> to change to logic later but that will always be risky - especially in
> the area when somebody want to make a user space driven memory
> management.

Think about MADV_FREE. It moves those pages into inactive file LRU's head.
See the get_scan_count which makes forceful scanning of inactive file LRU
if it has enough size based on the memory pressure.
The reason is it's likely to have used-once pages in inactive file LRU,
generally. Those pages has been top-priority candidate to be reclaimed
for a long time.

Only parts I am aware of moving pages into tail of inactive LRU are places
writeback is done for pages VM already decide to reclaim by LRU aging or
destructive operation like invalidating but couldn't completed. It's
really strong hints with no doubt.

>  
> > > What should happen for shared pages? In other words do we want to allow
> > > less privileged process to control evicting of shared pages with a more
> > > privileged one? E.g. think of all sorts of side channel attacks. Maybe
> > > we want to do the same thing as for mincore where write access is
> > > required.
> > 
> > It doesn't work with shared pages(ie, page_mapcount > 1). I will add it
> > in the description.
> 
> OK, this is good for the starter. It makes the implementation simpler
> and we can add shared mappings coverage later.
> 
> Although I would argue that touching only writeable mappings should be
> reasonably safe.
> 
> -- 
> Michal Hocko
> SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20 22:54     ` Minchan Kim
@ 2019-05-21  6:04       ` Michal Hocko
  2019-05-21  9:11         ` Minchan Kim
  0 siblings, 1 reply; 18+ messages in thread
From: Michal Hocko @ 2019-05-21  6:04 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Tue 21-05-19 07:54:19, Minchan Kim wrote:
> On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote:
[...]
> > > Internally, it works via deactivating memory from active list to
> > > inactive's head so when the memory pressure happens, they will be
> > > reclaimed earlier than other active pages unless there is no
> > > access until the time.
> > 
> > Could you elaborate about the decision to move to the head rather than
> > tail? What should happen to inactive pages? Should we move them to the
> > tail? Your implementation seems to ignore those completely. Why?
> 
> Normally, inactive LRU could have used-once pages without any mapping
> to user's address space. Such pages would be better candicate to
> reclaim when the memory pressure happens. With deactivating only
> active LRU pages of the process to the head of inactive LRU, we will
> keep them in RAM longer than used-once pages and could have more chance
> to be activated once the process is resumed.

You are making some assumptions here. You have an explicit call what is
cold now you are assuming something is even colder. Is this assumption a
general enough to make people depend on it? Not that we wouldn't be able
to change to logic later but that will always be risky - especially in
the area when somebody want to make a user space driven memory
management.
 
> > What should happen for shared pages? In other words do we want to allow
> > less privileged process to control evicting of shared pages with a more
> > privileged one? E.g. think of all sorts of side channel attacks. Maybe
> > we want to do the same thing as for mincore where write access is
> > required.
> 
> It doesn't work with shared pages(ie, page_mapcount > 1). I will add it
> in the description.

OK, this is good for the starter. It makes the implementation simpler
and we can add shared mappings coverage later.

Although I would argue that touching only writeable mappings should be
reasonably safe.

-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  8:19     ` Michal Hocko
  2019-05-20 15:08       ` Suren Baghdasaryan
@ 2019-05-20 22:55       ` Minchan Kim
  1 sibling, 0 replies; 18+ messages in thread
From: Minchan Kim @ 2019-05-20 22:55 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Mon, May 20, 2019 at 10:19:43AM +0200, Michal Hocko wrote:
> On Mon 20-05-19 10:16:21, Michal Hocko wrote:
> > [CC linux-api]
> > 
> > On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> > > When a process expects no accesses to a certain memory range
> > > it could hint kernel that the pages can be reclaimed
> > > when memory pressure happens but data should be preserved
> > > for future use.  This could reduce workingset eviction so it
> > > ends up increasing performance.
> > > 
> > > This patch introduces the new MADV_COOL hint to madvise(2)
> > > syscall. MADV_COOL can be used by a process to mark a memory range
> > > as not expected to be used in the near future. The hint can help
> > > kernel in deciding which pages to evict early during memory
> > > pressure.
> > 
> > I do not want to start naming fight but MADV_COOL sounds a bit
> > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
> > or MADV_DONTNEED_PRESERVE.
> 
> OK, I can see that you have used MADV_COLD for a different mode.
> So this one is effectively a non destructive MADV_FREE alternative
> so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD
> in other patch would then be MADV_DONTNEED_PRESERVE. Right?

Correct.


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  8:16   ` Michal Hocko
  2019-05-20  8:19     ` Michal Hocko
@ 2019-05-20 22:54     ` Minchan Kim
  2019-05-21  6:04       ` Michal Hocko
  1 sibling, 1 reply; 18+ messages in thread
From: Minchan Kim @ 2019-05-20 22:54 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote:
> [CC linux-api]

Thanks, Michal. I forgot to add it.

> 
> On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> > When a process expects no accesses to a certain memory range
> > it could hint kernel that the pages can be reclaimed
> > when memory pressure happens but data should be preserved
> > for future use.  This could reduce workingset eviction so it
> > ends up increasing performance.
> > 
> > This patch introduces the new MADV_COOL hint to madvise(2)
> > syscall. MADV_COOL can be used by a process to mark a memory range
> > as not expected to be used in the near future. The hint can help
> > kernel in deciding which pages to evict early during memory
> > pressure.
> 
> I do not want to start naming fight but MADV_COOL sounds a bit
> misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
> or MADV_DONTNEED_PRESERVE.

Thanks for the suggestion. Since I got several suggestions, Let's discuss
them all at once in cover-letter.

> 
> > Internally, it works via deactivating memory from active list to
> > inactive's head so when the memory pressure happens, they will be
> > reclaimed earlier than other active pages unless there is no
> > access until the time.
> 
> Could you elaborate about the decision to move to the head rather than
> tail? What should happen to inactive pages? Should we move them to the
> tail? Your implementation seems to ignore those completely. Why?

Normally, inactive LRU could have used-once pages without any mapping
to user's address space. Such pages would be better candicate to
reclaim when the memory pressure happens. With deactivating only
active LRU pages of the process to the head of inactive LRU, we will
keep them in RAM longer than used-once pages and could have more chance
to be activated once the process is resumed.

> 
> What should happen for shared pages? In other words do we want to allow
> less privileged process to control evicting of shared pages with a more
> privileged one? E.g. think of all sorts of side channel attacks. Maybe
> we want to do the same thing as for mincore where write access is
> required.

It doesn't work with shared pages(ie, page_mapcount > 1). I will add it
in the description.

> -- 
> Michal Hocko
> SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  8:19     ` Michal Hocko
@ 2019-05-20 15:08       ` Suren Baghdasaryan
  2019-05-20 22:55       ` Minchan Kim
  1 sibling, 0 replies; 18+ messages in thread
From: Suren Baghdasaryan @ 2019-05-20 15:08 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner,
	Tim Murray, Joel Fernandes, Daniel Colascione, Shakeel Butt,
	Sonny Rao, Brian Geffon, linux-api

On Mon, May 20, 2019 at 1:19 AM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Mon 20-05-19 10:16:21, Michal Hocko wrote:
> > [CC linux-api]
> >
> > On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> > > When a process expects no accesses to a certain memory range
> > > it could hint kernel that the pages can be reclaimed
> > > when memory pressure happens but data should be preserved
> > > for future use.  This could reduce workingset eviction so it
> > > ends up increasing performance.
> > >
> > > This patch introduces the new MADV_COOL hint to madvise(2)
> > > syscall. MADV_COOL can be used by a process to mark a memory range
> > > as not expected to be used in the near future. The hint can help
> > > kernel in deciding which pages to evict early during memory
> > > pressure.
> >
> > I do not want to start naming fight but MADV_COOL sounds a bit
> > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
> > or MADV_DONTNEED_PRESERVE.
>
> OK, I can see that you have used MADV_COLD for a different mode.
> So this one is effectively a non destructive MADV_FREE alternative
> so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD
> in other patch would then be MADV_DONTNEED_PRESERVE. Right?
>

I agree that naming them this way would be more in-line with the
existing API. Another good option IMO could be MADV_RECLAIM_NOW /
MADV_RECLAIM_LAZY which might explain a bit better what they do but
Michal's proposal is more consistent with the current API.

> --
> Michal Hocko
> SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  8:16   ` Michal Hocko
@ 2019-05-20  8:19     ` Michal Hocko
  2019-05-20 15:08       ` Suren Baghdasaryan
  2019-05-20 22:55       ` Minchan Kim
  2019-05-20 22:54     ` Minchan Kim
  1 sibling, 2 replies; 18+ messages in thread
From: Michal Hocko @ 2019-05-20  8:19 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

On Mon 20-05-19 10:16:21, Michal Hocko wrote:
> [CC linux-api]
> 
> On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> > When a process expects no accesses to a certain memory range
> > it could hint kernel that the pages can be reclaimed
> > when memory pressure happens but data should be preserved
> > for future use.  This could reduce workingset eviction so it
> > ends up increasing performance.
> > 
> > This patch introduces the new MADV_COOL hint to madvise(2)
> > syscall. MADV_COOL can be used by a process to mark a memory range
> > as not expected to be used in the near future. The hint can help
> > kernel in deciding which pages to evict early during memory
> > pressure.
> 
> I do not want to start naming fight but MADV_COOL sounds a bit
> misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
> or MADV_DONTNEED_PRESERVE.

OK, I can see that you have used MADV_COLD for a different mode.
So this one is effectively a non destructive MADV_FREE alternative
so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD
in other patch would then be MADV_DONTNEED_PRESERVE. Right?

-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* Re: [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim
@ 2019-05-20  8:16   ` Michal Hocko
  2019-05-20  8:19     ` Michal Hocko
  2019-05-20 22:54     ` Minchan Kim
  2019-05-28  8:53   ` Hillf Danton
  2019-05-28 10:58   ` Minchan Kim
  2 siblings, 2 replies; 18+ messages in thread
From: Michal Hocko @ 2019-05-20  8:16 UTC (permalink / raw)
  To: Minchan Kim
  Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, linux-api

[CC linux-api]

On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> When a process expects no accesses to a certain memory range
> it could hint kernel that the pages can be reclaimed
> when memory pressure happens but data should be preserved
> for future use.  This could reduce workingset eviction so it
> ends up increasing performance.
> 
> This patch introduces the new MADV_COOL hint to madvise(2)
> syscall. MADV_COOL can be used by a process to mark a memory range
> as not expected to be used in the near future. The hint can help
> kernel in deciding which pages to evict early during memory
> pressure.

I do not want to start naming fight but MADV_COOL sounds a bit
misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
or MADV_DONTNEED_PRESERVE.

> Internally, it works via deactivating memory from active list to
> inactive's head so when the memory pressure happens, they will be
> reclaimed earlier than other active pages unless there is no
> access until the time.

Could you elaborate about the decision to move to the head rather than
tail? What should happen to inactive pages? Should we move them to the
tail? Your implementation seems to ignore those completely. Why?

What should happen for shared pages? In other words do we want to allow
less privileged process to control evicting of shared pages with a more
privileged one? E.g. think of all sorts of side channel attacks. Maybe
we want to do the same thing as for mincore where write access is
required.
-- 
Michal Hocko
SUSE Labs


^ permalink raw reply	[flat|nested] 18+ messages in thread

* [RFC 1/7] mm: introduce MADV_COOL
  2019-05-20  3:52 [RFC 0/7] introduce memory hinting API for external process Minchan Kim
@ 2019-05-20  3:52 ` Minchan Kim
  2019-05-20  8:16   ` Michal Hocko
                     ` (2 more replies)
  0 siblings, 3 replies; 18+ messages in thread
From: Minchan Kim @ 2019-05-20  3:52 UTC (permalink / raw)
  To: Andrew Morton
  Cc: LKML, linux-mm, Michal Hocko, Johannes Weiner, Tim Murray,
	Joel Fernandes, Suren Baghdasaryan, Daniel Colascione,
	Shakeel Butt, Sonny Rao, Brian Geffon, Minchan Kim

When a process expects no accesses to a certain memory range
it could hint kernel that the pages can be reclaimed
when memory pressure happens but data should be preserved
for future use.  This could reduce workingset eviction so it
ends up increasing performance.

This patch introduces the new MADV_COOL hint to madvise(2)
syscall. MADV_COOL can be used by a process to mark a memory range
as not expected to be used in the near future. The hint can help
kernel in deciding which pages to evict early during memory
pressure.

Internally, it works via deactivating memory from active list to
inactive's head so when the memory pressure happens, they will be
reclaimed earlier than other active pages unless there is no
access until the time.

* v1r2
 * use clear_page_young in deactivate_page - joelaf

* v1r1
 * Revise the description - surenb
 * Renaming from MADV_WARM to MADV_COOL - surenb

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/page-flags.h             |   1 +
 include/linux/page_idle.h              |  15 ++++
 include/linux/swap.h                   |   1 +
 include/uapi/asm-generic/mman-common.h |   1 +
 mm/madvise.c                           | 112 +++++++++++++++++++++++++
 mm/swap.c                              |  43 ++++++++++
 6 files changed, 173 insertions(+)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 9f8712a4b1a5..58b06654c8dd 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -424,6 +424,7 @@ static inline bool set_hwpoison_free_buddy_page(struct page *page)
 TESTPAGEFLAG(Young, young, PF_ANY)
 SETPAGEFLAG(Young, young, PF_ANY)
 TESTCLEARFLAG(Young, young, PF_ANY)
+CLEARPAGEFLAG(Young, young, PF_ANY)
 PAGEFLAG(Idle, idle, PF_ANY)
 #endif
 
diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h
index 1e894d34bdce..f3f43b317150 100644
--- a/include/linux/page_idle.h
+++ b/include/linux/page_idle.h
@@ -19,6 +19,11 @@ static inline void set_page_young(struct page *page)
 	SetPageYoung(page);
 }
 
+static inline void clear_page_young(struct page *page)
+{
+	ClearPageYoung(page);
+}
+
 static inline bool test_and_clear_page_young(struct page *page)
 {
 	return TestClearPageYoung(page);
@@ -65,6 +70,16 @@ static inline void set_page_young(struct page *page)
 	set_bit(PAGE_EXT_YOUNG, &page_ext->flags);
 }
 
+static void clear_page_young(struct page *page)
+{
+	struct page_ext *page_ext = lookup_page_ext(page);
+
+	if (unlikely(!page_ext))
+		return;
+
+	clear_bit(PAGE_EXT_YOUNG, &page_ext->flags);
+}
+
 static inline bool test_and_clear_page_young(struct page *page)
 {
 	struct page_ext *page_ext = lookup_page_ext(page);
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4bfb5c4ac108..64795abea003 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -340,6 +340,7 @@ extern void lru_add_drain_cpu(int cpu);
 extern void lru_add_drain_all(void);
 extern void rotate_reclaimable_page(struct page *page);
 extern void deactivate_file_page(struct page *page);
+extern void deactivate_page(struct page *page);
 extern void mark_page_lazyfree(struct page *page);
 extern void swap_setup(void);
 
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index abd238d0f7a4..f7a4a5d4b642 100644
--- a/include/uapi/asm-generic/mman-common.h
+++ b/include/uapi/asm-generic/mman-common.h
@@ -42,6 +42,7 @@
 #define MADV_SEQUENTIAL	2		/* expect sequential page references */
 #define MADV_WILLNEED	3		/* will need these pages */
 #define MADV_DONTNEED	4		/* don't need these pages */
+#define MADV_COOL	5		/* deactivatie these pages */
 
 /* common parameters: try to keep these consistent across architectures */
 #define MADV_FREE	8		/* free pages only if memory pressure */
diff --git a/mm/madvise.c b/mm/madvise.c
index 628022e674a7..c05817fb570d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -8,6 +8,7 @@
 
 #include <linux/mman.h>
 #include <linux/pagemap.h>
+#include <linux/page_idle.h>
 #include <linux/syscalls.h>
 #include <linux/mempolicy.h>
 #include <linux/page-isolation.h>
@@ -40,6 +41,7 @@ static int madvise_need_mmap_write(int behavior)
 	case MADV_REMOVE:
 	case MADV_WILLNEED:
 	case MADV_DONTNEED:
+	case MADV_COOL:
 	case MADV_FREE:
 		return 0;
 	default:
@@ -307,6 +309,113 @@ static long madvise_willneed(struct vm_area_struct *vma,
 	return 0;
 }
 
+static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
+{
+	pte_t *orig_pte, *pte, ptent;
+	spinlock_t *ptl;
+	struct page *page;
+	struct vm_area_struct *vma = walk->vma;
+	unsigned long next;
+
+	next = pmd_addr_end(addr, end);
+	if (pmd_trans_huge(*pmd)) {
+		spinlock_t *ptl;
+
+		ptl = pmd_trans_huge_lock(pmd, vma);
+		if (!ptl)
+			return 0;
+
+		if (is_huge_zero_pmd(*pmd))
+			goto huge_unlock;
+
+		page = pmd_page(*pmd);
+		if (page_mapcount(page) > 1)
+			goto huge_unlock;
+
+		if (next - addr != HPAGE_PMD_SIZE) {
+			int err;
+
+			get_page(page);
+			spin_unlock(ptl);
+			lock_page(page);
+			err = split_huge_page(page);
+			unlock_page(page);
+			put_page(page);
+			if (!err)
+				goto regular_page;
+			return 0;
+		}
+
+		pmdp_test_and_clear_young(vma, addr, pmd);
+		deactivate_page(page);
+huge_unlock:
+		spin_unlock(ptl);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+
+regular_page:
+	orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) {
+		ptent = *pte;
+
+		if (pte_none(ptent))
+			continue;
+
+		if (!pte_present(ptent))
+			continue;
+
+		page = vm_normal_page(vma, addr, ptent);
+		if (!page)
+			continue;
+
+		if (page_mapcount(page) > 1)
+			continue;
+
+		ptep_test_and_clear_young(vma, addr, pte);
+		deactivate_page(page);
+	}
+
+	pte_unmap_unlock(orig_pte, ptl);
+	cond_resched();
+
+	return 0;
+}
+
+static void madvise_cool_page_range(struct mmu_gather *tlb,
+			     struct vm_area_struct *vma,
+			     unsigned long addr, unsigned long end)
+{
+	struct mm_walk cool_walk = {
+		.pmd_entry = madvise_cool_pte_range,
+		.mm = vma->vm_mm,
+	};
+
+	tlb_start_vma(tlb, vma);
+	walk_page_range(addr, end, &cool_walk);
+	tlb_end_vma(tlb, vma);
+}
+
+static long madvise_cool(struct vm_area_struct *vma,
+			unsigned long start_addr, unsigned long end_addr)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
+
+	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
+		return -EINVAL;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
+	madvise_cool_page_range(&tlb, vma, start_addr, end_addr);
+	tlb_finish_mmu(&tlb, start_addr, end_addr);
+
+	return 0;
+}
+
 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 				unsigned long end, struct mm_walk *walk)
 
@@ -695,6 +804,8 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
 		return madvise_remove(vma, prev, start, end);
 	case MADV_WILLNEED:
 		return madvise_willneed(vma, prev, start, end);
+	case MADV_COOL:
+		return madvise_cool(vma, start, end);
 	case MADV_FREE:
 	case MADV_DONTNEED:
 		return madvise_dontneed_free(vma, prev, start, end, behavior);
@@ -716,6 +827,7 @@ madvise_behavior_valid(int behavior)
 	case MADV_WILLNEED:
 	case MADV_DONTNEED:
 	case MADV_FREE:
+	case MADV_COOL:
 #ifdef CONFIG_KSM
 	case MADV_MERGEABLE:
 	case MADV_UNMERGEABLE:
diff --git a/mm/swap.c b/mm/swap.c
index 3a75722e68a9..0f94c3b5397d 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -46,6 +46,7 @@ int page_cluster;
 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
+static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
 static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
 #ifdef CONFIG_SMP
 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
@@ -537,6 +538,23 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
 	update_page_reclaim_stat(lruvec, file, 0);
 }
 
+static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
+			    void *arg)
+{
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
+		int file = page_is_file_cache(page);
+		int lru = page_lru_base_type(page);
+
+		del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
+		ClearPageActive(page);
+		ClearPageReferenced(page);
+		clear_page_young(page);
+		add_page_to_lru_list(page, lruvec, lru);
+
+		__count_vm_events(PGDEACTIVATE, hpage_nr_pages(page));
+		update_page_reclaim_stat(lruvec, file, 0);
+	}
+}
 
 static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
 			    void *arg)
@@ -589,6 +607,10 @@ void lru_add_drain_cpu(int cpu)
 	if (pagevec_count(pvec))
 		pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
 
+	pvec = &per_cpu(lru_deactivate_pvecs, cpu);
+	if (pagevec_count(pvec))
+		pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
+
 	pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
 	if (pagevec_count(pvec))
 		pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
@@ -622,6 +644,26 @@ void deactivate_file_page(struct page *page)
 	}
 }
 
+/*
+ * deactivate_page - deactivate a page
+ * @page: page to deactivate
+ *
+ * deactivate_page() moves @page to the inactive list if @page was on the active
+ * list and was not an unevictable page.  This is done to accelerate the reclaim
+ * of @page.
+ */
+void deactivate_page(struct page *page)
+{
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
+		struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
+
+		get_page(page);
+		if (!pagevec_add(pvec, page) || PageCompound(page))
+			pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
+		put_cpu_var(lru_deactivate_pvecs);
+	}
+}
+
 /**
  * mark_page_lazyfree - make an anon page lazyfree
  * @page: page to deactivate
@@ -686,6 +728,7 @@ void lru_add_drain_all(void)
 		if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
 		    pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
 		    pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
+		    pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
 		    pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
 		    need_activate_page_drain(cpu)) {
 			INIT_WORK(work, lru_add_drain_per_cpu);
-- 
2.21.0.1020.gf2820cf01a-goog


^ permalink raw reply	[flat|nested] 18+ messages in thread

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Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-28 12:15 [RFC 1/7] mm: introduce MADV_COOL Hillf Danton
2019-05-28 12:39 ` Minchan Kim
  -- strict thread matches above, loose matches on Subject: below --
2019-05-29  8:52 Hillf Danton
2019-05-29  2:40 Hillf Danton
2019-05-29  5:05 ` Michal Hocko
2019-05-28 15:38 Hillf Danton
2019-05-28 16:11 ` Michal Hocko
2019-05-20  3:52 [RFC 0/7] introduce memory hinting API for external process Minchan Kim
2019-05-20  3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim
2019-05-20  8:16   ` Michal Hocko
2019-05-20  8:19     ` Michal Hocko
2019-05-20 15:08       ` Suren Baghdasaryan
2019-05-20 22:55       ` Minchan Kim
2019-05-20 22:54     ` Minchan Kim
2019-05-21  6:04       ` Michal Hocko
2019-05-21  9:11         ` Minchan Kim
2019-05-21 10:05           ` Michal Hocko
2019-05-28  8:53   ` Hillf Danton
2019-05-28 10:58   ` Minchan Kim

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