[PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem v2
Driver fault callbacks are allowed to drop the mmap_sem when expecting
long hardware waits to avoid blocking other mm users. Allow the mkwrite
callbacks to do the same by returning early on VM_FAULT_RETRY.
In particular we want to be able to drop the mmap_sem when waiting for
a reservation object lock on a GPU buffer object. These locks may be
held while waiting for the GPU.
Cc: Andrew Morton
Cc: Matthew Wilcox
Cc: Will Deacon
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Minchan Kim
Cc: Michal Hocko
Cc: Huang Ying
Cc: Souptick Joarder
Cc: "Jérôme Glisse"
Cc: linux...@kvack.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Thomas Hellstrom
Reviewed-by: Ralph Campbell
---
v2: Make the order error codes we check for consistent with
the order used in the rest of the file.
---
mm/memory.c | 10 ++
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index e11ca9dd823f..9580d894f963 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
ret = vmf->vma->vm_ops->page_mkwrite(vmf);
/* Restore original flags so that caller is not surprised */
vmf->flags = old_flags;
- if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
if (unlikely(!(ret & VM_FAULT_LOCKED))) {
lock_page(page);
@@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
vmf->flags |= FAULT_FLAG_MKWRITE;
ret = vma->vm_ops->pfn_mkwrite(vmf);
- if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
+ if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))
return ret;
return finish_mkwrite_fault(vmf);
}
@@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp || (tmp &
- (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
+ VM_FAULT_RETRY {
put_page(vmf->page);
return tmp;
}
@@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
unlock_page(vmf->page);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp ||
- (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
+ VM_FAULT_RETRY {
put_page(vmf->page);
return tmp;
}
--
2.20.1
___
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Re: [PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem
On Wed, Apr 17, 2019 at 4:28 PM Thomas Hellstrom wrote:
>
> Hi, Souptick,
>
> On Sat, 2019-04-13 at 20:41 +0530, Souptick Joarder wrote:
> > On Fri, Apr 12, 2019 at 9:34 PM Thomas Hellstrom <
> > thellst...@vmware.com> wrote:
> > > Driver fault callbacks are allowed to drop the mmap_sem when
> > > expecting
> > > long hardware waits to avoid blocking other mm users. Allow the
> > > mkwrite
> > > callbacks to do the same by returning early on VM_FAULT_RETRY.
> > >
> > > In particular we want to be able to drop the mmap_sem when waiting
> > > for
> > > a reservation object lock on a GPU buffer object. These locks may
> > > be
> > > held while waiting for the GPU.
> > >
> > > Cc: Andrew Morton
> > > Cc: Matthew Wilcox
> > > Cc: Will Deacon
> > > Cc: Peter Zijlstra
> > > Cc: Rik van Riel
> > > Cc: Minchan Kim
> > > Cc: Michal Hocko
> > > Cc: Huang Ying
> > > Cc: Souptick Joarder
> > > Cc: "Jérôme Glisse"
> > > Cc: linux...@kvack.org
> > > Cc: linux-ker...@vger.kernel.org
> > >
> > > Signed-off-by: Thomas Hellstrom
> > > ---
> > > mm/memory.c | 10 ++
> > > 1 file changed, 6 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index e11ca9dd823f..a95b4a3b1ae2 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct
> > > vm_fault *vmf)
> > > ret = vmf->vma->vm_ops->page_mkwrite(vmf);
> > > /* Restore original flags so that caller is not surprised
> > > */
> > > vmf->flags = old_flags;
> > > - if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
> > > + if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> > > VM_FAULT_NOPAGE)))
> >
> > With this patch there will multiple instances of (VM_FAULT_ERROR |
> > VM_FAULT_RETRY | VM_FAULT_NOPAGE)
> > in mm/memory.c. Does it make sense to wrap it in a macro and use it ?
>
> Even though the code will look neater, it might be trickier to follow a
> particular error path. Could we perhaps postpone to a follow-up patch?
Sure. follow-up-patch is fine.
>
> Thomas
>
>
>
> >
> > > return ret;
> > > if (unlikely(!(ret & VM_FAULT_LOCKED))) {
> > > lock_page(page);
> > > @@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct
> > > vm_fault *vmf)
> > > pte_unmap_unlock(vmf->pte, vmf->ptl);
> > > vmf->flags |= FAULT_FLAG_MKWRITE;
> > > ret = vma->vm_ops->pfn_mkwrite(vmf);
> > > - if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
> > > + if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> > > VM_FAULT_NOPAGE))
> > > return ret;
> > > return finish_mkwrite_fault(vmf);
> > > }
> > > @@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct
> > > vm_fault *vmf)
> > > pte_unmap_unlock(vmf->pte, vmf->ptl);
> > > tmp = do_page_mkwrite(vmf);
> > > if (unlikely(!tmp || (tmp &
> > > - (VM_FAULT_ERROR |
> > > VM_FAULT_NOPAGE {
> > > + (VM_FAULT_ERROR |
> > > VM_FAULT_RETRY |
> > > + VM_FAULT_NOPAGE {
> > > put_page(vmf->page);
> > > return tmp;
> > > }
> > > @@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct
> > > vm_fault *vmf)
> > > unlock_page(vmf->page);
> > > tmp = do_page_mkwrite(vmf);
> > > if (unlikely(!tmp ||
> > > - (tmp & (VM_FAULT_ERROR |
> > > VM_FAULT_NOPAGE {
> > > + (tmp & (VM_FAULT_ERROR |
> > > VM_FAULT_RETRY |
> > > + VM_FAULT_NOPAGE {
> > > put_page(vmf->page);
> > > return tmp;
> > > }
> > > --
> > > 2.20.1
> > >
___
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Re: [PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem
Hi, Souptick,
On Sat, 2019-04-13 at 20:41 +0530, Souptick Joarder wrote:
> On Fri, Apr 12, 2019 at 9:34 PM Thomas Hellstrom <
> thellst...@vmware.com> wrote:
> > Driver fault callbacks are allowed to drop the mmap_sem when
> > expecting
> > long hardware waits to avoid blocking other mm users. Allow the
> > mkwrite
> > callbacks to do the same by returning early on VM_FAULT_RETRY.
> >
> > In particular we want to be able to drop the mmap_sem when waiting
> > for
> > a reservation object lock on a GPU buffer object. These locks may
> > be
> > held while waiting for the GPU.
> >
> > Cc: Andrew Morton
> > Cc: Matthew Wilcox
> > Cc: Will Deacon
> > Cc: Peter Zijlstra
> > Cc: Rik van Riel
> > Cc: Minchan Kim
> > Cc: Michal Hocko
> > Cc: Huang Ying
> > Cc: Souptick Joarder
> > Cc: "Jérôme Glisse"
> > Cc: linux...@kvack.org
> > Cc: linux-ker...@vger.kernel.org
> >
> > Signed-off-by: Thomas Hellstrom
> > ---
> > mm/memory.c | 10 ++
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/memory.c b/mm/memory.c
> > index e11ca9dd823f..a95b4a3b1ae2 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct
> > vm_fault *vmf)
> > ret = vmf->vma->vm_ops->page_mkwrite(vmf);
> > /* Restore original flags so that caller is not surprised
> > */
> > vmf->flags = old_flags;
> > - if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
> > + if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> > VM_FAULT_NOPAGE)))
>
> With this patch there will multiple instances of (VM_FAULT_ERROR |
> VM_FAULT_RETRY | VM_FAULT_NOPAGE)
> in mm/memory.c. Does it make sense to wrap it in a macro and use it ?
Even though the code will look neater, it might be trickier to follow a
particular error path. Could we perhaps postpone to a follow-up patch?
Thomas
>
> > return ret;
> > if (unlikely(!(ret & VM_FAULT_LOCKED))) {
> > lock_page(page);
> > @@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct
> > vm_fault *vmf)
> > pte_unmap_unlock(vmf->pte, vmf->ptl);
> > vmf->flags |= FAULT_FLAG_MKWRITE;
> > ret = vma->vm_ops->pfn_mkwrite(vmf);
> > - if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
> > + if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> > VM_FAULT_NOPAGE))
> > return ret;
> > return finish_mkwrite_fault(vmf);
> > }
> > @@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct
> > vm_fault *vmf)
> > pte_unmap_unlock(vmf->pte, vmf->ptl);
> > tmp = do_page_mkwrite(vmf);
> > if (unlikely(!tmp || (tmp &
> > - (VM_FAULT_ERROR |
> > VM_FAULT_NOPAGE {
> > + (VM_FAULT_ERROR |
> > VM_FAULT_RETRY |
> > + VM_FAULT_NOPAGE {
> > put_page(vmf->page);
> > return tmp;
> > }
> > @@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct
> > vm_fault *vmf)
> > unlock_page(vmf->page);
> > tmp = do_page_mkwrite(vmf);
> > if (unlikely(!tmp ||
> > - (tmp & (VM_FAULT_ERROR |
> > VM_FAULT_NOPAGE {
> > + (tmp & (VM_FAULT_ERROR |
> > VM_FAULT_RETRY |
> > + VM_FAULT_NOPAGE {
> > put_page(vmf->page);
> > return tmp;
> > }
> > --
> > 2.20.1
> >
___
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Re: [PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem
On 4/12/19 9:04 AM, Thomas Hellstrom wrote:
Driver fault callbacks are allowed to drop the mmap_sem when expecting
long hardware waits to avoid blocking other mm users. Allow the mkwrite
callbacks to do the same by returning early on VM_FAULT_RETRY.
In particular we want to be able to drop the mmap_sem when waiting for
a reservation object lock on a GPU buffer object. These locks may be
held while waiting for the GPU.
Cc: Andrew Morton
Cc: Matthew Wilcox
Cc: Will Deacon
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Minchan Kim
Cc: Michal Hocko
Cc: Huang Ying
Cc: Souptick Joarder
Cc: "Jérôme Glisse"
Cc: linux...@kvack.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Thomas Hellstrom
Reviewed-by: Ralph Campbell
---
mm/memory.c | 10 ++
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index e11ca9dd823f..a95b4a3b1ae2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
ret = vmf->vma->vm_ops->page_mkwrite(vmf);
/* Restore original flags so that caller is not surprised */
vmf->flags = old_flags;
- if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE)))
A very minor nit, for consistency elsewhere in mm/memory.c,
could you make this be:
(VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)
return ret;
if (unlikely(!(ret & VM_FAULT_LOCKED))) {
lock_page(page);
@@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
vmf->flags |= FAULT_FLAG_MKWRITE;
ret = vma->vm_ops->pfn_mkwrite(vmf);
- if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
+ if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE))
return ret;
return finish_mkwrite_fault(vmf);
}
@@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp || (tmp &
- (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (VM_FAULT_ERROR | VM_FAULT_RETRY |
+ VM_FAULT_NOPAGE {
put_page(vmf->page);
return tmp;
}
@@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
unlock_page(vmf->page);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp ||
- (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (tmp & (VM_FAULT_ERROR | VM_FAULT_RETRY |
+ VM_FAULT_NOPAGE {
put_page(vmf->page);
return tmp;
}
___
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Re: [PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem
On Fri, Apr 12, 2019 at 9:34 PM Thomas Hellstrom wrote:
>
> Driver fault callbacks are allowed to drop the mmap_sem when expecting
> long hardware waits to avoid blocking other mm users. Allow the mkwrite
> callbacks to do the same by returning early on VM_FAULT_RETRY.
>
> In particular we want to be able to drop the mmap_sem when waiting for
> a reservation object lock on a GPU buffer object. These locks may be
> held while waiting for the GPU.
>
> Cc: Andrew Morton
> Cc: Matthew Wilcox
> Cc: Will Deacon
> Cc: Peter Zijlstra
> Cc: Rik van Riel
> Cc: Minchan Kim
> Cc: Michal Hocko
> Cc: Huang Ying
> Cc: Souptick Joarder
> Cc: "Jérôme Glisse"
> Cc: linux...@kvack.org
> Cc: linux-ker...@vger.kernel.org
>
> Signed-off-by: Thomas Hellstrom
> ---
> mm/memory.c | 10 ++
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index e11ca9dd823f..a95b4a3b1ae2 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
> ret = vmf->vma->vm_ops->page_mkwrite(vmf);
> /* Restore original flags so that caller is not surprised */
> vmf->flags = old_flags;
> - if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
> + if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> VM_FAULT_NOPAGE)))
With this patch there will multiple instances of (VM_FAULT_ERROR |
VM_FAULT_RETRY | VM_FAULT_NOPAGE)
in mm/memory.c. Does it make sense to wrap it in a macro and use it ?
> return ret;
> if (unlikely(!(ret & VM_FAULT_LOCKED))) {
> lock_page(page);
> @@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
> pte_unmap_unlock(vmf->pte, vmf->ptl);
> vmf->flags |= FAULT_FLAG_MKWRITE;
> ret = vma->vm_ops->pfn_mkwrite(vmf);
> - if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
> + if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE))
> return ret;
> return finish_mkwrite_fault(vmf);
> }
> @@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
> pte_unmap_unlock(vmf->pte, vmf->ptl);
> tmp = do_page_mkwrite(vmf);
> if (unlikely(!tmp || (tmp &
> - (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
> + (VM_FAULT_ERROR | VM_FAULT_RETRY |
> + VM_FAULT_NOPAGE {
> put_page(vmf->page);
> return tmp;
> }
> @@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
> unlock_page(vmf->page);
> tmp = do_page_mkwrite(vmf);
> if (unlikely(!tmp ||
> - (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
> + (tmp & (VM_FAULT_ERROR | VM_FAULT_RETRY |
> + VM_FAULT_NOPAGE {
> put_page(vmf->page);
> return tmp;
> }
> --
> 2.20.1
>
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[PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem
Driver fault callbacks are allowed to drop the mmap_sem when expecting
long hardware waits to avoid blocking other mm users. Allow the mkwrite
callbacks to do the same by returning early on VM_FAULT_RETRY.
In particular we want to be able to drop the mmap_sem when waiting for
a reservation object lock on a GPU buffer object. These locks may be
held while waiting for the GPU.
Cc: Andrew Morton
Cc: Matthew Wilcox
Cc: Will Deacon
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Minchan Kim
Cc: Michal Hocko
Cc: Huang Ying
Cc: Souptick Joarder
Cc: "Jérôme Glisse"
Cc: linux...@kvack.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Thomas Hellstrom
---
mm/memory.c | 10 ++
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index e11ca9dd823f..a95b4a3b1ae2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
ret = vmf->vma->vm_ops->page_mkwrite(vmf);
/* Restore original flags so that caller is not surprised */
vmf->flags = old_flags;
- if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE)))
return ret;
if (unlikely(!(ret & VM_FAULT_LOCKED))) {
lock_page(page);
@@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
vmf->flags |= FAULT_FLAG_MKWRITE;
ret = vma->vm_ops->pfn_mkwrite(vmf);
- if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
+ if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE))
return ret;
return finish_mkwrite_fault(vmf);
}
@@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp || (tmp &
- (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (VM_FAULT_ERROR | VM_FAULT_RETRY |
+ VM_FAULT_NOPAGE {
put_page(vmf->page);
return tmp;
}
@@ -3494,7 +3495,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
unlock_page(vmf->page);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp ||
- (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE {
+ (tmp & (VM_FAULT_ERROR | VM_FAULT_RETRY |
+ VM_FAULT_NOPAGE {
put_page(vmf->page);
return tmp;
}
--
2.20.1
___
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