On Wed, Jul 10, 2024 at 03:22:49PM GMT, Liam R. Howlett wrote: > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> > > The MAP_FIXED page count is available after the vms_gather_munmap_vmas() > call, so use it instead of looping over the vmas twice. This commit message doesn't explain the 'Move may_expand_vm()' part of this change which is the patch's subject. Should add a little blurb about that. > > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> > --- > mm/mmap.c | 36 ++++-------------------------------- > 1 file changed, 4 insertions(+), 32 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 18c269bf8703..7a440e7da55a 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -401,27 +401,6 @@ anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) > anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); > } > > -static unsigned long count_vma_pages_range(struct mm_struct *mm, > - unsigned long addr, unsigned long end, > - unsigned long *nr_accounted) > -{ > - VMA_ITERATOR(vmi, mm, addr); > - struct vm_area_struct *vma; > - unsigned long nr_pages = 0; > - > - *nr_accounted = 0; > - for_each_vma_range(vmi, vma, end) { > - unsigned long vm_start = max(addr, vma->vm_start); > - unsigned long vm_end = min(end, vma->vm_end); > - > - nr_pages += PHYS_PFN(vm_end - vm_start); > - if (vma->vm_flags & VM_ACCOUNT) > - *nr_accounted += PHYS_PFN(vm_end - vm_start); > - } > - > - return nr_pages; > -} > - > static void __vma_link_file(struct vm_area_struct *vma, > struct address_space *mapping) > { > @@ -2949,17 +2928,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > pgoff_t vm_pgoff; > int error = -ENOMEM; > VMA_ITERATOR(vmi, mm, addr); > - unsigned long nr_pages, nr_accounted; > - > - nr_pages = count_vma_pages_range(mm, addr, end, &nr_accounted); > - > - /* > - * Check against address space limit. > - * MAP_FIXED may remove pages of mappings that intersects with requested > - * mapping. Account for the pages it would unmap. > - */ > - if (!may_expand_vm(mm, vm_flags, pglen - nr_pages)) > - return -ENOMEM; > > > /* Find the first overlapping VMA */ > @@ -2987,6 +2955,10 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > vma_iter_next_range(&vmi); > } > > + /* Check against address space limit. */ > + if (!may_expand_vm(mm, vm_flags, pglen - vms.nr_pages)) > + goto abort_munmap; > + > /* > * Private writable mapping: check memory availability > */ > -- > 2.43.0 > This is fine though as discussed previously, though obviously need to think about the arch_unmap() bit :) Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>