[SRU][F/U][PATCH 0/1] prevent swap storms by disabling high watermark boosting

[Andrea Righi]

BugLink: https://bugs.launchpad.net/bugs/1861359

[Impact]

High watermark boosting can cause large swap activity under certain
memory intensive workloads, making the system very unresponsive (screen
does not refresh, keyboard not responding, etc.).

This large swap activity seems to be prevented disabling high watermark
boosting.

[Test case]

Opening this web page in chrome seems to be a good reproducer of the
problem:

https://platform.leolabs.space/visualizations/conjunction?type=conjunction&reportId=2004981040

When this page is opened we can clearly see from 'top' (for example)
that the used swap is going up very quickly.

With the fix applied swap is not used at all and the system is always
responsive.

[Fix]

Set vm.watermark_boost_factor to 0, disabling watermark boosting by
default.

[Regression potential]

Regression potential is minimal, setting vm.watermark_boost_factor to 0
by default restores the old kernel behavior before watermark boosting
was introduced. In case of unexpected regressions we can always fix this
in user-space via sysctl.

----------------------------------------------------------------
Andrea Righi (1):
      UBUNTU: SAUCE: mm/page_alloc.c: disable memory reclaim watermark boosting by default

 mm/page_alloc.c | 13 -------------
 1 file changed, 13 deletions(-)