Messages in this thread Patch in this message | | | From | Thomas Hellstrom <> | Subject | [PATCH 1/9] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem v2 | Date | Wed, 24 Apr 2019 12:00:12 +0000 |
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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> --- 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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