From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> Instead of moving (or leaving) the vma iterator pointing at the previous vma, leave it pointing at the insert location. Pointing the vma iterator at the insert location allows for a cleaner walk of the vma tree for MAP_FIXED and the no expansion cases. The vma_prev() call in the case of merging the previous vma is equivalent to vma_iter_prev_range(), since the vma iterator will be pointing to the location just before the previous vma. Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> --- mm/mmap.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 722bcced0499..b940de8c6df8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2962,21 +2962,22 @@ unsigned long mmap_region(struct file *file, unsigned long addr, mas_init(&mas_detach, &mt_detach, /* addr = */ 0); /* Prepare to unmap any existing mapping in the area */ if (vms_gather_munmap_vmas(&vms, &mas_detach)) - return -ENOMEM; + goto gather_failed; /* Remove any existing mappings from the vma tree */ if (vma_iter_clear_gfp(&vmi, addr, end, GFP_KERNEL)) - return -ENOMEM; + goto clear_tree_failed; /* Unmap any existing mapping in the area */ vms_complete_munmap_vmas(&vms, &mas_detach); next = vms.next; prev = vms.prev; - vma_prev(&vmi); vma = NULL; } else { next = vma_next(&vmi); prev = vma_prev(&vmi); + if (prev) + vma_iter_next_range(&vmi); } /* @@ -2989,11 +2990,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vm_flags |= VM_ACCOUNT; } - if (vm_flags & VM_SPECIAL) { - if (prev) - vma_iter_next_range(&vmi); + if (vm_flags & VM_SPECIAL) goto cannot_expand; - } /* Attempt to expand an old mapping */ /* Check next */ @@ -3014,19 +3012,21 @@ unsigned long mmap_region(struct file *file, unsigned long addr, merge_start = prev->vm_start; vma = prev; vm_pgoff = prev->vm_pgoff; - } else if (prev) { - vma_iter_next_range(&vmi); + vma_prev(&vmi); /* Equivalent to going to the previous range */ } - /* Actually expand, if possible */ - if (vma && - !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) { - khugepaged_enter_vma(vma, vm_flags); - goto expanded; + if (vma) { + /* Actually expand, if possible */ + if (!vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) { + khugepaged_enter_vma(vma, vm_flags); + goto expanded; + } + + /* If the expand fails, then reposition the vma iterator */ + if (unlikely(vma == prev)) + vma_iter_set(&vmi, addr); } - if (vma == prev) - vma_iter_set(&vmi, addr); cannot_expand: /* @@ -3187,6 +3187,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vm_unacct_memory(charged); validate_mm(mm); return error; + +clear_tree_failed: + abort_munmap_vmas(&mas_detach); +gather_failed: + validate_mm(mm); + return -ENOMEM; } static int __vm_munmap(unsigned long start, size_t len, bool unlock) -- 2.43.0