Yes I can sorta confirm the bug is in uswsusp. I removed the package and pm-utils and used both "systemctl hibernate" and "echo disk >> /sys/power/state" to hibernate. It seems to succeed and shuts down, I am just not able to resume from it, which seems to be a classical problem solved just by setting the resume swap file/partition on grub. (which i tried and didn't work even with nvidia disabled) Anyway uswsusp is still necessary because the default kernel hibernation doesn't work with the proprietary nvidia drivers as long as I know and tested. Is there anyway I could get any workaround to this bug on my current OS by the way? On Wed, Apr 3, 2019 at 7:04 AM Rainer Fiebig <jrf@xxxxxxxxxxx> wrote: > > Am 03.04.19 um 11:34 schrieb Jan Kara: > > On Tue 02-04-19 16:25:00, Andrew Morton wrote: > >> > >> I cc'ed a bunch of people from bugzilla. > >> > >> Folks, please please please remember to reply via emailed > >> reply-to-all. Don't use the bugzilla interface! > >> > >> On Mon, 16 Jun 2014 18:29:26 +0200 "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx> wrote: > >> > >>> On 6/13/2014 6:55 AM, Johannes Weiner wrote: > >>>> On Fri, Jun 13, 2014 at 01:50:47AM +0200, Rafael J. Wysocki wrote: > >>>>> On 6/13/2014 12:02 AM, Johannes Weiner wrote: > >>>>>> On Tue, May 06, 2014 at 01:45:01AM +0200, Rafael J. Wysocki wrote: > >>>>>>> On 5/6/2014 1:33 AM, Johannes Weiner wrote: > >>>>>>>> Hi Oliver, > >>>>>>>> > >>>>>>>> On Mon, May 05, 2014 at 11:00:13PM +0200, Oliver Winker wrote: > >>>>>>>>> Hello, > >>>>>>>>> > >>>>>>>>> 1) Attached a full function-trace log + other SysRq outputs, see [1] > >>>>>>>>> attached. > >>>>>>>>> > >>>>>>>>> I saw bdi_...() calls in the s2disk paths, but didn't check in detail > >>>>>>>>> Probably more efficient when one of you guys looks directly. > >>>>>>>> Thanks, this looks interesting. balance_dirty_pages() wakes up the > >>>>>>>> bdi_wq workqueue as it should: > >>>>>>>> > >>>>>>>> [ 249.148009] s2disk-3327 2.... 48550413us : global_dirty_limits <-balance_dirty_pages_ratelimited > >>>>>>>> [ 249.148009] s2disk-3327 2.... 48550414us : global_dirtyable_memory <-global_dirty_limits > >>>>>>>> [ 249.148009] s2disk-3327 2.... 48550414us : writeback_in_progress <-balance_dirty_pages_ratelimited > >>>>>>>> [ 249.148009] s2disk-3327 2.... 48550414us : bdi_start_background_writeback <-balance_dirty_pages_ratelimited > >>>>>>>> [ 249.148009] s2disk-3327 2.... 48550414us : mod_delayed_work_on <-balance_dirty_pages_ratelimited > >>>>>>>> but the worker wakeup doesn't actually do anything: > >>>>>>>> [ 249.148009] kworker/-3466 2d... 48550431us : finish_task_switch <-__schedule > >>>>>>>> [ 249.148009] kworker/-3466 2.... 48550431us : _raw_spin_lock_irq <-worker_thread > >>>>>>>> [ 249.148009] kworker/-3466 2d... 48550431us : need_to_create_worker <-worker_thread > >>>>>>>> [ 249.148009] kworker/-3466 2d... 48550432us : worker_enter_idle <-worker_thread > >>>>>>>> [ 249.148009] kworker/-3466 2d... 48550432us : too_many_workers <-worker_enter_idle > >>>>>>>> [ 249.148009] kworker/-3466 2.... 48550432us : schedule <-worker_thread > >>>>>>>> [ 249.148009] kworker/-3466 2.... 48550432us : __schedule <-worker_thread > >>>>>>>> > >>>>>>>> My suspicion is that this fails because the bdi_wq is frozen at this > >>>>>>>> point and so the flush work never runs until resume, whereas before my > >>>>>>>> patch the effective dirty limit was high enough so that image could be > >>>>>>>> written in one go without being throttled; followed by an fsync() that > >>>>>>>> then writes the pages in the context of the unfrozen s2disk. > >>>>>>>> > >>>>>>>> Does this make sense? Rafael? Tejun? > >>>>>>> Well, it does seem to make sense to me. > >>>>>> From what I see, this is a deadlock in the userspace suspend model and > >>>>>> just happened to work by chance in the past. > >>>>> Well, it had been working for quite a while, so it was a rather large > >>>>> opportunity > >>>>> window it seems. :-) > >>>> No doubt about that, and I feel bad that it broke. But it's still a > >>>> deadlock that can't reasonably be accommodated from dirty throttling. > >>>> > >>>> It can't just put the flushers to sleep and then issue a large amount > >>>> of buffered IO, hoping it doesn't hit the dirty limits. Don't shoot > >>>> the messenger, this bug needs to be addressed, not get papered over. > >>>> > >>>>>> Can we patch suspend-utils as follows? > >>>>> Perhaps we can. Let's ask the new maintainer. > >>>>> > >>>>> Rodolfo, do you think you can apply the patch below to suspend-utils? > >>>>> > >>>>>> Alternatively, suspend-utils > >>>>>> could clear the dirty limits before it starts writing and restore them > >>>>>> post-resume. > >>>>> That (and the patch too) doesn't seem to address the problem with existing > >>>>> suspend-utils > >>>>> binaries, however. > >>>> It's userspace that freezes the system before issuing buffered IO, so > >>>> my conclusion was that the bug is in there. This is arguable. I also > >>>> wouldn't be opposed to a patch that sets the dirty limits to infinity > >>>> from the ioctl that freezes the system or creates the image. > >>> > >>> OK, that sounds like a workable plan. > >>> > >>> How do I set those limits to infinity? > >> > >> Five years have passed and people are still hitting this. > >> > >> Killian described the workaround in comment 14 at > >> https://bugzilla.kernel.org/show_bug.cgi?id=75101. > >> > >> People can use this workaround manually by hand or in scripts. But we > >> really should find a proper solution. Maybe special-case the freezing > >> of the flusher threads until all the writeout has completed. Or > >> something else. > > > > I've refreshed my memory wrt this bug and I believe the bug is really on > > the side of suspend-utils (uswsusp or however it is called). They are low > > level system tools, they ask the kernel to freeze all processes > > (SNAPSHOT_FREEZE ioctl), and then they rely on buffered writeback (which is > > relatively heavyweight infrastructure) to work. That is wrong in my > > opinion. > > > > I can see Johanness was suggesting in comment 11 to use O_SYNC in > > suspend-utils which worked but was too slow. Indeed O_SYNC is rather big > > hammer but using O_DIRECT should be what they need and get better > > performance - no additional buffering in the kernel, no dirty throttling, > > etc. They only need their buffer & device offsets sector aligned - they > > seem to be even page aligned in suspend-utils so they should be fine. And > > if the performance still sucks (currently they appear to do mostly random > > 4k writes so it probably would for rotating disks), they could use AIO DIO > > to get multiple pages in flight (as many as they dare to allocate buffers) > > and then the IO scheduler will reorder things as good as it can and they > > should get reasonable performance. > > > > Is there someone who works on suspend-utils these days? Because the repo > > I've found on kernel.org seems to be long dead (last commit in 2012). > > > > Honza > > > > Whether it's suspend-utils (or uswsusp) or not could be answered quickly > by de-installing this package and using the kernel-methods instead. > >
