Comment 27 for bug 1833281

(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Tue, 22 Aug 2017 11:17:08 +0000 <email address hidden> wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=196729
>
> Bug ID: 196729
> Summary: System becomes unresponsive when swapping - Regression
> since 4.10.x
> Product: Memory Management
> Version: 2.5
> Kernel Version: 4.11.x / 4.12.x
> Hardware: All
> OS: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: Page Allocator
> Assignee: <email address hidden>
> Reporter: <email address hidden>
> Regression: No

So it's "Regression: yes". More info at the bugzilla link.

> I have 10Gb of RAM in this system and run Fedora 26. If I launch Cities:
> Skylines with no swap space, things run well performance wise until I get an
> OOM - and it all dies - which is expected.
>
> When I turn on swap to /dev/sda2 which resides on an SSD, I get complete
> system freezes while swap is being accessed.
>
> The first swap was after loading a saved game, then launching kmail in the
> background. This caused ~500Mb to be swapped to /dev/sda2 on an SSD. The
> system froze for about 8 minutes - barely being able to move the mouse. The
> HDD LED was on constantly during the entire time.
>
> To hopefully rule out the above glibc issue, I started the game via jemalloc
> -
> but experienced even more severe freezes while swapping. I gave up waiting
> after 13 minutes of non-responsiveness - not even being able to move the
> mouse
> properly.
>
> During these hangs, I could typed into a Konsole window, and some of the
> typing took 3+ minutes to display on the screen (yay for buffers?).
>
> I have tested this with both the default vm.swappiness values, as well as the
> following:
> vm.swappiness = 1
> vm.min_free_kbytes = 32768
> vm.vfs_cache_pressure = 60
>
> I noticed that when I do eventually get screen updates, all 8 cpus (4 cores /
> 2 threads) show 100% CPU usage - and kswapd is right up there in the process
> list for CPU usage. Sadly I haven't been able to capture this information
> fully yet due to said unresponsiveness.
>
> (more to come in comments & attachments)
>
> --
> You are receiving this mail because:
> You are the assignee for the bug.