Re: [PATCH v2 2/2] hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race

[Kirill A. Shutemov]

On Fri, Dec 21, 2018 at 02:17:32PM -0800, Mike Kravetz wrote:
> Am I misunderstanding your question/concern?

No. Thanks for the clarification.

> 
> I have decided to add the locking (although unnecessary) with something like
> this in hugetlbfs_evict_inode.
> 
> 	/*
> 	 * The vfs layer guarantees that there are no other users of this
> 	 * inode.  Therefore, it would be safe to call remove_inode_hugepages
> 	 * without holding i_mmap_rwsem.  We acquire and hold here to be
> 	 * consistent with other callers.  Since there will be no contention
> 	 * on the semaphore, overhead is negligible.
> 	 */
> 	i_mmap_lock_write(mapping);
> 	remove_inode_hugepages(inode, 0, LLONG_MAX);
> 	i_mmap_unlock_write(mapping);

LGTM.

-- 
 Kirill A. Shutemov