On 09/21, Theodore Ts'o wrote: > On Wed, Sep 20, 2017 at 10:02:37PM -0700, Jaegeuk Kim wrote: > > > > Yes, and actually, android retries umount(2) for several seconds, if it gets > > failure. So, first I thought it'd be better to make umount() more deterministic. > > > > I'm not sure how many times we can retry and wait for this. IMHO, it'd be better > > to use this together with the new flag, since this can detect unclosed namespace > > given successful umount(2). > > Even if you could make umount wait for the binder deferred workqueue > to exit, if it takes time, it takes time. And that's not the core > VFS's fault. It's binder's. > > So... why not fix this by adding a binder ioctl which forces its > workqueue to be flushed, and use that *before* you try calling mount? Yes, we can, but I'm not 100% sure this happens only by binder. This is caused by delayed_fput/mntput called by any kernel thread which would be much generic. > If that binder ioctl takes minutes or hours to complete, then that's a > binder bug, and needs to be fixed in binder. > > - Ted
