[Trusty] Hang and corruption in dcache_shrink_list

[Dave Chiluk]

I did some more review of the recent dcache changes that have gone in
upstream, and I think it's appropriate for us to bring those in as well.

I hope pushed my branch 70318 to
http://kernel.ubuntu.com/git?p=chiluk/ubuntu-trusty.git;a=shortlog;h=refs/heads/70318
for review.

Basically I included all upstream patches related to locking (or their
requisite code cleanup patches) that pertain to dcache_shrink_list.

Dave.

On 08/12/2014 08:59 AM, Tim Gardner wrote:
> On 08/08/2014 12:18 PM, Dave Chiluk wrote:
>> BugLink: http://bugs.launchpad.net/bugs/1354157
>>
>> The patchset described here and committed to upstream
>> https://lkml.org/lkml/2014/5/4/7
>> can be cleanly cherry-picked, and has been applied to
>> git://kernel.ubuntu.com/chiluk/ubuntu-trusty.git branch 70318
>> The end user reports that the above patch set fixes the issue.
>>
>> I'd like to get some additional review on this patchset before
>> submitting it for actual inclusion.
>>
>> That all being said, I think we should strongly consider pulling in
>> 046b961b4
>> b2b80195d
>> 9f12600fe
>> and b2b80195d88
>> as well, as these look to be more related to a possible lock starvation
>> case.
>>
>> Open for discussion.
>> Dave.
>>
> 
> I did an identical patch set for a different bug
> (http://bugs.launchpad.net/bugs/1354234). Shall we dup them ?
> 
> The following changes since commit 0a0caf5157bffb6340de804b3a8c94e045f68fb7:
> 
>   ahci_xgene: Use correct OOB tunning parameters for APM X-Gene SoC AHCI
> SATA Host controller driver. (2014-08-12 06:40:52 -0600)
> 
> are available in the git repository at:
> 
>   git://kernel.ubuntu.com/rtg/ubuntu-trusty.git
> lp1354234-dcache-shrink-list-corruption
> 
> for you to fetch changes up to 3b1cbde08418dbd8cc2d819b9e7412303818deba:
> 
>   dcache: don't need rcu in shrink_dentry_list() (2014-08-12 07:47:39 -0600)
> 
> ----------------------------------------------------------------
> Al Viro (7):
>       fold d_kill() and d_free()
>       fold try_prune_one_dentry()
>       new helper: dentry_free()
>       expand the call of dentry_lru_del() in dentry_kill()
>       dentry_kill(): don't try to remove from shrink list
>       don't remove from shrink list in select_collect()
>       more graceful recovery in umount_collect()
> 
> Miklos Szeredi (1):
>       dcache: don't need rcu in shrink_dentry_list()
> 
>  fs/dcache.c            | 315
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>  include/linux/dcache.h |   2 ++
>  2 files changed, 103 insertions(+), 214 deletions(-)
> 
>