Re: [PATCH][RFC v4] PM / Hibernate: Feed the wathdog when creating snapshot

[Rafael J. Wysocki]

On Monday, August 21, 2017 9:48:17 AM CEST Chen Yu wrote:
> On Mon, Aug 21, 2017 at 08:47:09AM +0200, Michal Hocko wrote:
> > On Sat 19-08-17 18:21:26, Chen Yu wrote:
> > > There is a problem that when counting the pages for creating
> > > the hibernation snapshot will take significant amount of
> > > time, especially on system with large memory. Since the counting
> > > job is performed with irq disabled, this might lead to NMI lockup.
> > > The following warning were found on a system with 1.5TB DRAM:
> > > 
> > > [ 1124.758184] Freezing user space processes ... (elapsed 0.002 seconds) done.
> > > [ 1124.768721] OOM killer disabled.
> > > [ 1124.847009] PM: Preallocating image memory...
> > > [ 1139.392042] NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
> > > [ 1139.392076] CPU: 27 PID: 3128 Comm: systemd-sleep Not tainted 4.13.0-0.rc2.git0.1.fc27.x86_64 #1
> > > [ 1139.392077] task: ffff9f01971ac000 task.stack: ffffb1a3f325c000
> > > [ 1139.392083] RIP: 0010:memory_bm_find_bit+0xf4/0x100
> > > [ 1139.392084] RSP: 0018:ffffb1a3f325fc20 EFLAGS: 00000006
> > > [ 1139.392084] RAX: 0000000000000000 RBX: 0000000013b83000 RCX: ffff9fbe89caf000
> > > [ 1139.392085] RDX: ffffb1a3f325fc30 RSI: 0000000000003200 RDI: ffff9fbeaffffe80
> > > [ 1139.392085] RBP: ffffb1a3f325fc40 R08: 0000000013b80000 R09: ffff9fbe89c54878
> > > [ 1139.392085] R10: ffffb1a3f325fc2c R11: 0000000013b83200 R12: 0000000000000400
> > > [ 1139.392086] R13: fffffd552e0c0000 R14: ffff9fc1bffd31e0 R15: 0000000000000202
> > > [ 1139.392086] FS:  00007f3189704180(0000) GS:ffff9fbec8ec0000(0000) knlGS:0000000000000000
> > > [ 1139.392087] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > [ 1139.392087] CR2: 00000085da0f7398 CR3: 000001771cf9a000 CR4: 00000000007406e0
> > > [ 1139.392088] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > [ 1139.392088] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > > [ 1139.392088] PKRU: 55555554
> > > [ 1139.392089] Call Trace:
> > > [ 1139.392092]  ? memory_bm_set_bit+0x29/0x60
> > > [ 1139.392094]  swsusp_set_page_free+0x2b/0x30
> > > [ 1139.392098]  mark_free_pages+0x147/0x1c0
> > > [ 1139.392099]  count_data_pages+0x41/0xa0
> > > [ 1139.392101]  hibernate_preallocate_memory+0x80/0x450
> > > [ 1139.392102]  hibernation_snapshot+0x58/0x410
> > > [ 1139.392103]  hibernate+0x17c/0x310
> > > [ 1139.392104]  state_store+0xdf/0xf0
> > > [ 1139.392107]  kobj_attr_store+0xf/0x20
> > > [ 1139.392111]  sysfs_kf_write+0x37/0x40
> > > [ 1139.392113]  kernfs_fop_write+0x11c/0x1a0
> > > [ 1139.392117]  __vfs_write+0x37/0x170
> > > [ 1139.392121]  ? handle_mm_fault+0xd8/0x230
> > > [ 1139.392122]  vfs_write+0xb1/0x1a0
> > > [ 1139.392123]  SyS_write+0x55/0xc0
> > > [ 1139.392126]  entry_SYSCALL_64_fastpath+0x1a/0xa5
> > > ...
> > > [ 1144.690405] done (allocated 6590003 pages)
> > > [ 1144.694971] PM: Allocated 26360012 kbytes in 19.89 seconds (1325.28 MB/s)
> > > 
> > > It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup
> > > was triggered. In case the timeout of the NMI watch dog has been
> > > set to 1 second, a safe interval should be 6590003/20 = 320k pages
> > > in theory. However there might also be some platforms running at a
> > > lower frequency, so feed the watchdog every 100k pages.
> > > 
> > > Reported-by: Jan Filipcewicz <jan.filipcewicz@xxxxxxxxx>
> > > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx>
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> > > Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> > > Cc: Vlastimil Babka <vbabka@xxxxxxx>
> > > Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> > > Cc: Len Brown <lenb@xxxxxxxxxx>
> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> > 
> > OK, this looks better. Feel free to add
> > Reviewed-by: Michal Hocko <mhocko@xxxxxxxx>
> >
> Thanks!

OK, so can you please resend the patch with a CC to linux-pm and
the Reviewed-by from Michal?

Thanks,
Rafael