From: Linus Torvalds <[email protected]> Date: Fri, 2 Sep 2016 11:13:09 -0700 (PDT)
> > From: Linus Torvalds <[email protected]> > Date: Thu, 1 Sep 2016 14:43:53 -0700 > Subject: [PATCH 2/2] af_unix: split 'u->readlock' into two: 'iolock' and > 'bindlock' > > Right now we use the 'readlock' both for protecting some of the af_unix > IO path and for making the bind be single-threaded. > > The two are independent, but using the same lock makes for a nasty > deadlock due to ordering with regards to filesystem locking. The bind > locking would want to nest outside the VSF pathname locking, but the IO > locking wants to nest inside some of those same locks. > > We tried to fix this earlier with commit c845acb324aa ("af_unix: Fix > splice-bind deadlock") which moved the readlock inside the vfs locks, > but that caused problems with overlayfs that will then call back into > filesystem routines that take the lock in the wrong order anyway. > > Splitting the locks means that we can go back to having the bind lock be > the outermost lock, and we don't have any deadlocks with lock ordering. > > Acked-by: Rainer Weikusat <[email protected]> > Acked-by: Al Viro <[email protected]> > Signed-off-by: Linus Torvalds <[email protected]> Applied.
