On Thu, Aug 11, 2011 at 04:40:59PM +1000, David Gibson wrote: > Linus, please apply > > hugetlbfs tracks the current usage of hugepages per hugetlbfs > mountpoint. To correctly track this when hugepages are released, it > must find the right hugetlbfs super_block from the struct page > available in free_huge_page(). a superblock is not a mountpoint, it's a filesystem instance. You can happily have a single filesystem mounted at multiple mount points. > However, this usage is buggy, because nothing ensures that the > address_space is not freed before all the hugepages that belonged to > it are. In practice that will usually be the case, but if extra page > references have been taken by e.g. drivers or kvm doing > get_user_pages() then the file, inode and address space may be > destroyed before all the pages. > > In addition, the quota functions use the mapping only to get the inode > then the super_block. However, most of the callers already have the > inode anyway and have to get the mapping from there. > > This patch, therefore, stores a pointer to the inode instead of the > address_space in the page private data for hugepages. What's sthe point? The lifetime of inode->i_mapping is exactly the same as that of the inode, except for those few filesystem that use one from a different inode (and then for the whole lifetime of the inode), so I can't see how your patch will make a difference. > More > importantly it correctly adjusts the reference count on the inodes > when they're added to the page private data. This ensures that the > inode (and therefore the super block) will not be freed before we use > it from free_huge_page. That seems like the real fix. And even if you'd still do the other bits it should be a separate patch/ -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
