On Wed, Dec 09, 2015 at 09:24:32AM -0800, Linus Torvalds wrote: > That's because of the HIGHMEM crap that you removed. Without > highmem, the page data address specifies the page fine without any > cookie. > > - overlayfs, which uses it to create a temporary data storage. > > Why? Mainly because it wants to hide the cookie in there. D'oh! Not really - it also wants to stash a way to underlying inode in there. See below... > - proc, which uses it to save the proc_dir_entry > > Why? The reason seems to be that we don't call put_link() with the > dentry that get_link got, so it can't look it up the sane way. What's more, that dentry might very well have gone negative by that point. Think what happens if, during the symlink traversal, we run into the hard "restart from scratch in non-RCU mode". We'll need to do ->put_link() on everything we have in stack. Regardless of what might've happened to dentries/inodes of symlinks involved - all we are really promised is that RCU-delayed parts of their destruction hadn't been entered yet. Note, BTW, that *all* ->put_link() instances ignore the inode argument and I seriously considered dropping it completely. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
