[PATCH] mremap: move_vma fixes and cleanup
From: Hugh Dickins <hugh@veritas.com> Partial rewrite of mremap's move_vma. Rajesh Venkatasubramanian has pointed out that vmtruncate could miss ptes, leaving orphaned pages, because move_vma only made the new vma visible after filling it. We see no good reason for that, and time to make move_vma more robust. Removed all its vma merging decisions, leave them to mmap.c's vma_merge, with copy_vma added. Removed duplicated is_mergeable_vma test from vma_merge, and duplicated validate_mm from insert_vm_struct. move_vma move from old to new then unmap old; but on error move back from new to old and unmap new. Don't unwind within move_page_tables, let move_vma call it explicitly to unwind, with the right source vma. Get the VM_ACCOUNTing right even when the final do_munmap fails.
Showing
Please register or sign in to comment