Am 03.04.19 um 18:59 schrieb Matheus Fillipe: > Yes I can sorta confirm the bug is in uswsusp. I removed the package > and pm-utils Matheus, there is no need to uninstall pm-utils. You actually need this to have comfortable suspend/hibernate. The only additional option you will get from uswsusp is true s2both (which is nice, imo). pm-utils provides something similar called "suspend-hybrid" which means that the computer suspends and after a configurable time wakes up again to go into hibernation. 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. What doesn't work: hibernating or resuming? And /var/log/pm-suspend.log might give you a clue what causes the problem. > > Is there anyway I could get any workaround to this bug on my current > OS by the way? *I* don't know, I don't use Ubuntu. But what I would do now is re-install pm-utils *without* uswsusp and make sure that you have got the swap-partition/file right in grub.cfg or menu.lst (grub legacy). Then do a few pm-hibernate/resume and tell us what happened. So long! > > 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. >> >>
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