Comment 26 for bug 1328727

Created attachment 134271
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 () ...").

With following test I can reproduce the problem reliably:
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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

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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.
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I've bisected this to following commit:
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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

[...]
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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