mmap() doesn't allow the non-anonymous mappings with VM_GROWS* bit set. In particular this means that mmap_region()->vma_merge(file, vm_flags) must always fail if vm_flags & VM_GROWS. So it does not make sense to check VM_GROWS* after we already allocated the new vma, the only caller, do_mmap_pgoff(), which can pass this flag can do the check itself.
And this looks a bit more correct, mmap_region() already unmapped the old mapping at this stage. But if mmap() is going to fail, it should avoid do_munmap() if possible. Signed-off-by: Oleg Nesterov <[email protected]> --- mm/mmap.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index f681e18..6b69352 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1327,6 +1327,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, } } + /* Only MAP_PRIVATE|MAP_ANONYMOUS can use MAP_GROWS */ + if ((vm_flags & VM_MAYSHARE) && (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))) + return -EINVAL; /* * Set 'VM_NORESERVE' if we should not account for the * memory use of this mapping. @@ -1542,11 +1545,7 @@ munmap_back: vma->vm_pgoff = pgoff; INIT_LIST_HEAD(&vma->anon_vma_chain); - error = -EINVAL; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */ - if (file) { - if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) - goto free_vma; if (vm_flags & VM_DENYWRITE) { error = deny_write_access(file); if (error) @@ -1571,8 +1570,6 @@ munmap_back: pgoff = vma->vm_pgoff; vm_flags = vma->vm_flags; } else if (vm_flags & VM_SHARED) { - if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP))) - goto free_vma; error = shmem_zero_setup(vma); if (error) goto free_vma; -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
