Hi Matthew, On Tue, Feb 13, 2018 at 07:16:08AM -0800, Matthew Wilcox wrote: > On Tue, Feb 13, 2018 at 12:58:51PM +0000, Will Deacon wrote: > > This patch resolves the livelock by not taking hlist_bl_lock in > > d_alloc_parallel if the sequence counter is odd, since any subsequent > > masked comparison with i_dir_seq will fail anyway. > > > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > Signed-off-by: Will Deacon <will.deacon@xxxxxxx> > > Reviewed-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Thanks! > I wonder whether it makes sense to turn i_dir_seq into a seqcount_t, > which would give us the lockdep checking as well. I'm not sure it's quite as simple as that. start_dir_add looks very much like it's intended to run concurrently, so we'd need a write_seqcount implementation that provides the same atomicity guarantees. Will
