Comment 28 for bug 1328727

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

On Tue, 29 Apr 2014 20:13:44 +0000 <email address hidden> wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=75101
>
> Bug ID: 75101
> Summary: [bisected] s2disk / hibernate blocks on "Saving 506031
> image data pages () ..."
> Product: Memory Management
> Version: 2.5
> Kernel Version: v3.14
> Hardware: All
> OS: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: Other
> Assignee: <email address hidden>
> Reporter: <email address hidden>
> Regression: No
>
> Created attachment 134271
> --> https://bugzilla.kernel.org/attachment.cgi?id=134271&action=edit
> Full console trace with various SysRq outputs
>
> Since v3.14 under normal desktop usage my s2disk/hibernate often blocks on
> the
> saving of the image data ("Saving 506031 image data pages () ...").

A means to reproduce as well as a bisection result. Nice! Thanks.

Johannes, could you please take a look?

> With following test I can reproduce the problem reliably:
> ---
> 0) Boot
>
> 1) Fill ram with 2GiB (+50% in my case)
>
> mount -t tmpfs tmpfs /media/test/
> dd if=/dev/zero of=/media/test/test0.bin bs=1k count=$[1024*1024]
> dd if=/dev/zero of=/media/test/test1.bin bs=1k count=$[1024*1024]
>
> 2) Do s2disk
>
> s2disk
>
> ---
> s2disk: Unable to switch virtual terminals, using the current console.
> s2disk: Snapshotting system
> s2disk: System snapshot ready. Preparing to write
> s2disk: Image size: 2024124 kilobytes
> s2disk: Free swap: 3791208 kilobytes
> s2disk: Saving 506031 image data pages (press backspace to abort) ... 0%
>
> #Problem>: ... there is stays and blocks. SysRq still responds, so that I
> could
> trigger various debug outputs.
> ---
>
> I've bisected this to following commit:
> ---
> commit a1c3bfb2f67ef766de03f1f56bdfff9c8595ab14 (HEAD, refs/bisect/bad)
> Author: Johannes Weiner <email address hidden>
> Date: Wed Jan 29 14:05:41 2014 -0800
>
> mm/page-writeback.c: do not count anon pages as dirtyable memory
>
> [...]
> ---
>
> Reverting a1c3bfb2 fixes s2disk for me again - so basically I'm ok ;). But
> maybe there is still another better solution.
>
> Attached is a full console trace with various SysRq outputs, possibly useful
> for analyzing.
>
> BR, Oliver
>