| Message ID | 20190412160338.64994-2-thellstrom@vmware.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Emulated coherent graphics memory | expand |
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 <akpm@linux-foundation.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Rik van Riel <riel@surriel.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Souptick Joarder <jrdr.linux@gmail.com> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> > --- > 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; > } >
On Fri, Apr 12, 2019 at 9:34 PM Thomas Hellstrom <thellstrom@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 <akpm@linux-foundation.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Rik van Riel <riel@surriel.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Souptick Joarder <jrdr.linux@gmail.com> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> > --- > 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 >
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 < > thellstrom@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 <akpm@linux-foundation.org> > > Cc: Matthew Wilcox <willy@infradead.org> > > Cc: Will Deacon <will.deacon@arm.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Rik van Riel <riel@surriel.com> > > Cc: Minchan Kim <minchan@kernel.org> > > Cc: Michal Hocko <mhocko@suse.com> > > Cc: Huang Ying <ying.huang@intel.com> > > Cc: Souptick Joarder <jrdr.linux@gmail.com> > > Cc: "Jérôme Glisse" <jglisse@redhat.com> > > Cc: linux-mm@kvack.org > > Cc: linux-kernel@vger.kernel.org > > > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> > > --- > > 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 > >
On Wed, Apr 17, 2019 at 4:28 PM Thomas Hellstrom <thellstrom@vmware.com> 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 < > > thellstrom@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 <akpm@linux-foundation.org> > > > Cc: Matthew Wilcox <willy@infradead.org> > > > Cc: Will Deacon <will.deacon@arm.com> > > > Cc: Peter Zijlstra <peterz@infradead.org> > > > Cc: Rik van Riel <riel@surriel.com> > > > Cc: Minchan Kim <minchan@kernel.org> > > > Cc: Michal Hocko <mhocko@suse.com> > > > Cc: Huang Ying <ying.huang@intel.com> > > > Cc: Souptick Joarder <jrdr.linux@gmail.com> > > > Cc: "Jérôme Glisse" <jglisse@redhat.com> > > > Cc: linux-mm@kvack.org > > > Cc: linux-kernel@vger.kernel.org > > > > > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> > > > --- > > > 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 > > >
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; }
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 <akpm@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> --- mm/memory.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)