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[0/2] re-enable remote per-cpu-pages draining

Message ID 20200616161149.392213902@fuller.cnet
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Series re-enable remote per-cpu-pages draining | expand

Message

Marcelo Tosatti June 16, 2020, 4:11 p.m. UTC 
Remote draining of pages was removed from 5.6-rt.

Unfortunately its necessary for use-cases which have a busy spinning
SCHED_FIFO thread on isolated CPU:

[ 7475.821066] INFO: task ld:274531 blocked for more than 600 seconds.
[ 7475.822157]       Not tainted 4.18.0-208.rt5.20.el8.x86_64 #1
[ 7475.823094] echo 0  /proc/sys/kernel/hung_task_timeout_secs disables this message.
[ 7475.824392] ld              D    0 274531 274530 0x00084080
[ 7475.825307] Call Trace:
[ 7475.825761]  __schedule+0x342/0x850
[ 7475.826377]  schedule+0x39/0xd0
[ 7475.826923]  schedule_timeout+0x20e/0x410
[ 7475.827610]  ? __schedule+0x34a/0x850
[ 7475.828247]  ? ___preempt_schedule+0x16/0x18
[ 7475.828953]  wait_for_completion+0x85/0xe0
[ 7475.829653]  flush_work+0x11a/0x1c0
[ 7475.830313]  ? flush_workqueue_prep_pwqs+0x130/0x130
[ 7475.831148]  drain_all_pages+0x140/0x190
[ 7475.831803]  __alloc_pages_slowpath+0x3f8/0xe20
[ 7475.832571]  ? mem_cgroup_commit_charge+0xcb/0x510
[ 7475.833371]  __alloc_pages_nodemask+0x1ca/0x2b0
[ 7475.834134]  pagecache_get_page+0xb5/0x2d0
[ 7475.834814]  ? account_page_dirtied+0x11a/0x220
[ 7475.835579]  grab_cache_page_write_begin+0x1f/0x40
[ 7475.836379]  iomap_write_begin.constprop.44+0x1c1/0x370
[ 7475.837241]  ? iomap_write_end+0x91/0x290
[ 7475.837911]  iomap_write_actor+0x92/0x170

See individual patches for details.