[Precise][Quantal][Raring][SRU][PATCH 0/1] Revert "zram: use zram->lock to protect zram_free_page() in swap free notify path"

[Luis Henriques]

BugLink: http://bugs.launchpad.net/bugs/1215513

SRU Justification:

Impact:

Users of the Precise, Quantal and Raring kernels using zram will
experience system freezes that will require a hard reset when the
system is under high memory pressure.

Fix:

This issue is actually fixed upstream with commit:

 a0c516c zram: don't grab mutex in zram_slot_free_noity

However, this commit doesn't apply cleanly and would require several
others to be applied.

Since zram is a staging driver, my suggestion is to simply revert the
offending upstream commit:

 57ab048 zram: use zram->lock to protect zram_free_page() in swap free notify path

Testcase:

I was able to reproduce the original problem on kvm, running Raring.

1. I've installed zram-config package which will activate zram devices as
   swap devices
2. Executed several applications to force swap to be used.

After a while, the system freezes.

(The same testcase with a kernel where this commit is reverted does not
cause the system freeze.)

Luis Henriques (1):
  Revert "zram: use zram->lock to protect zram_free_page() in swap free
    notify path"

 drivers/staging/zram/zram_drv.c | 2 --
 drivers/staging/zram/zram_drv.h | 5 ++---
 2 files changed, 2 insertions(+), 5 deletions(-)

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1.8.3.2