On 8/5/24 14:13, Lorenzo Stoakes wrote: > Equally use struct vma_merge_struct to abstract parameters for VMA > expansion and shrinking. > > This leads the way to further refactoring and de-duplication by > standardising the interface. > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> > --- > mm/mmap.c | 30 +++++++++++-------- > mm/vma.c | 66 ++++++++++++++++++----------------------- > mm/vma.h | 8 ++--- > tools/testing/vma/vma.c | 18 +++++++++-- > 4 files changed, 65 insertions(+), 57 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 721ced6e37b0..04145347c245 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1367,7 +1367,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > pgoff_t pglen = len >> PAGE_SHIFT; > unsigned long charged = 0; > unsigned long end = addr + len; > - unsigned long merge_start = addr, merge_end = end; > bool writable_file_mapping = false; > int error; > VMA_ITERATOR(vmi, mm, addr); > @@ -1423,28 +1422,26 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > /* Attempt to expand an old mapping */ > /* Check next */ > if (next && next->vm_start == end && can_vma_merge_before(&vmg)) { > - merge_end = next->vm_end; > - vma = next; > + /* We can adjust this as can_vma_merge_after() doesn't touch */ > + vmg.end = next->vm_end; Ugh, ok but wonder how fragile that is. > + vma = vmg.vma = next; > vmg.pgoff = next->vm_pgoff - pglen; > - } > > - if (vma) { > + /* We may merge our NULL anon_vma with non-NULL in next. */ Hm now I realize the if (vma) block probably didn't need to be added in patch 2 only to removed here, it could have been part of the if (next && ...) block above already? Which is not that important, but... > vmg.anon_vma = vma->anon_vma; > - vmg.uffd_ctx = vma->vm_userfaultfd_ctx; I don't see why it's now ok to remove this line? Was it intended? In patch 2 it made sense to me to add it so the can_vma_merge_after() still has the right ctx for comparing, and this didn't change? > } > > /* Check prev */ > if (prev && prev->vm_end == addr && can_vma_merge_after(&vmg)) { > - merge_start = prev->vm_start; > - vma = prev; > + vmg.start = prev->vm_start; > + vma = vmg.vma = prev; > vmg.pgoff = prev->vm_pgoff; > } else if (prev) { > vma_iter_next_range(&vmi); > } > > /* Actually expand, if possible */ > - if (vma && > - !vma_expand(&vmi, vma, merge_start, merge_end, vmg.pgoff, next)) { > + if (vma && !vma_expand(&vmg)) { > khugepaged_enter_vma(vma, vm_flags); > goto expanded; > } > @@ -2359,6 +2356,13 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift) > VMA_ITERATOR(vmi, mm, new_start); > struct vm_area_struct *next; > struct mmu_gather tlb; > + struct vma_merge_struct vmg = { > + .vmi = &vmi, > + .vma = vma, > + .start = new_start, > + .end = old_end, > + .pgoff = vma->vm_pgoff, > + }; > > BUG_ON(new_start > new_end); > > @@ -2373,7 +2377,7 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift) > /* > * cover the whole range: [new_start, old_end) > */ > - if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL)) > + if (vma_expand(&vmg)) > return -ENOMEM; > > /* > @@ -2406,6 +2410,8 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift) > tlb_finish_mmu(&tlb); > > vma_prev(&vmi); > + vmg.end = new_end; > + > /* Shrink the vma to just the new range */ > - return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff); > + return vma_shrink(&vmg); The vma_shrink() doesn't seem to benefit that much from vmg conversion but I guess why not. Maybe this will further change anyway...