Re: BUG_ON hit in "reimplement path_mountpoint() with less magic" [Was: Re: linux-next: Tree for Jan 13]

[Al Viro]

On Mon, Jan 13, 2020 at 01:27:34PM -0500, Jason A. Donenfeld wrote:
> Hi Al,
> 
> Your "reimplement path_mountpoint() with less magic" commit is causing
> oopses on the linux-next tests running on https://build.wireguard.com/ .
> Here's one such crash with debug symbols:

Check if that persists with the version currently in #fixes (commit
7a955b7363b8).  It ought to be fixed there; quick check is to look
at fs/namei.c:path_mountpoint() in your tree - it should read
	if (!err && (nd->flags & LOOKUP_RCU))
		err = unlazy_walk(nd);
not
	if (!err)
		err = unlazy_walk(nd);
as in the broken variant.