* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [220414 02:51]: > On Mon, 4 Apr 2022 14:35:43 +0000 Liam Howlett <liam.howlett@xxxxxxxxxx> wrote: > > > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> > > > > Changing mmap_region() to use the maple tree state and the advanced > > maple tree interface allows for a lot less tree walking. > > > > This change removes the last caller of munmap_vma_range(), so drop this > > unused function. > > > > Add vma_expand() to expand a VMA if possible by doing the necessary > > hugepage check, uprobe_munmap of files, dcache flush, modifications then > > undoing the detaches, etc. > > > > Merging this with Yang Shi's "mm: mmap: register suitable readonly file > vmas for khugepaged" > (https://lkml.kernel.org/r/20220404200250.321455-9-shy828301@xxxxxxxxx) > > > ... > > > > @@ -1741,13 +1868,28 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > > goto free_vma; > > } > > > > - vma_link(mm, vma, prev); > > + if (vma->vm_file) > > + i_mmap_lock_write(vma->vm_file->f_mapping); > > + > > + vma_mas_store(vma, &mas); > > + __vma_link_list(mm, vma, prev); > > + mm->map_count++; > > + if (vma->vm_file) { > > + if (vma->vm_flags & VM_SHARED) > > + mapping_allow_writable(vma->vm_file->f_mapping); > > + > > + flush_dcache_mmap_lock(vma->vm_file->f_mapping); > > + vma_interval_tree_insert(vma, &vma->vm_file->f_mapping->i_mmap); > > + flush_dcache_mmap_unlock(vma->vm_file->f_mapping); > > + i_mmap_unlock_write(vma->vm_file->f_mapping); > > + } > > + > > /* Once vma denies write, undo our temporary denial count */ > > unmap_writable: > > if (file && vm_flags & VM_SHARED) > > mapping_unmap_writable(file->f_mapping); > > I'm unsure whether this hunk should be inside or outside the call to > the cheerfully undocumented khugepaged_enter_vma()? Below. I've replaced the vma_link() with a write to the tree and inlined the handling of vm_file. At least, it will keep with what Yang Shi wrote in the patch you are merging. > > > Code snippet as I presently have it: > > if (vma->vm_file) > i_mmap_lock_write(vma->vm_file->f_mapping); > > vma_mas_store(vma, &mas); > mm->map_count++; > if (vma->vm_file) { > if (vma->vm_flags & VM_SHARED) > mapping_allow_writable(vma->vm_file->f_mapping); > > flush_dcache_mmap_lock(vma->vm_file->f_mapping); > vma_interval_tree_insert(vma, &vma->vm_file->f_mapping->i_mmap); > flush_dcache_mmap_unlock(vma->vm_file->f_mapping); > i_mmap_unlock_write(vma->vm_file->f_mapping); > } > > /* > * vma_merge() calls khugepaged_enter_vma() either, the below > * call covers the non-merge case. > */ > khugepaged_enter_vma(vma, vma->vm_flags); > > /* Once vma denies write, undo our temporary denial count */ > unmap_writable: > if (file && vm_flags & VM_SHARED) > mapping_unmap_writable(file->f_mapping); > > btw, "vma_merge() calls khugepaged_enter_vma() either" isn't > understandable. Should that be "also"? It looks like it should be "also" to me.. Yang Shi?
