On Sun, Apr 15, 2018 at 10:54:55PM +0100, Al Viro wrote: > On Sun, Apr 15, 2018 at 09:40:54PM +0100, Al Viro wrote: > > > BTW, the current placement of cond_resched() looks bogus; suppose we > > have collected a lot of victims and ran into need_resched(). We leave > > d_walk() and call shrink_dentry_list(). At that point there's a lot > > of stuff on our shrink list and anybody else running into them will > > have to keep scanning. Giving up the timeslice before we take care > > of any of those looks like a bad idea, to put it mildly, and that's > > precisely what will happen. > > > > What about doing that in the end of __dentry_kill() instead? And to > > hell with both existing call sites - dput() one (before going to > > the parent) is obviously covered by that (dentry_kill() only returns > > non-NULL after having called __dentry_kill()) and in shrink_dentry_list() > > we'll get to it as soon as we go through all dentries that can be > > immediately kicked off the shrink list. Which, AFAICS, improves the > > situation, now that shrink_lock_dentry() contains no trylock loops... > > > > Comments? > > What I mean is something like this (cumulative diff, it'll obviously need > to be carved up into 3--4 commits):
... and carved-up version is in vfs.git#work.dcache. Could syzbot folks hit it with their reproducers?