Hi Miklos. On Mon, 2008-10-27 at 12:12 +0100, Miklos Szeredi wrote: > On Sun, 26 Oct 2008, Rafael J. Wysocki wrote: > > On Saturday, 25 of October 2008, Nigel Cunningham wrote: > > > While working on freezing fuse filesystems, I found that if a filesystem > > > is frozen when we try to freeze processes, freezing can fail because > > > threads are waiting in vfs_check_frozen for the filesystem to be thawed. > > > We should thus not count such threads. > > > > > > The check will be safe if a filesystem is thawed while we're freezing > > > processes because filesystem thaws are only invoked from userspace. Any > > > waiting processes will be woken and frozen prior to us completing the > > > freezing of userspace (the caller invoking the filesystem thaw will be > > > freezing) or - in the worst case - together with kernel threads. > > The description is missing some details: why is the filesystem frozen > before suspend? AFAICS this can happen when DM calls bdev_freeze() on > the device before the task freezing begins. Is this the case? It doesn't matter why a process is sitting in that wait_event call. What does matter is that one can be there. In the case where I saw it, I was working on fuse freezing. I don't remember the details, as it's a year since I made this patch, but I don't think I wasn't using fuse or DM. > Also, while the patch might solve some of the symptoms of the fuse > vs. process freezer interaction, it will not fully fix that problem. > As such it's just a hack to hide the problem, making it less likely to > appear. No, it's part of the solution. I haven't posted the full fuse freezing patch because I thought this could be profitably merged without the rest of the patch. Regards, Nigel _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
