Re: [PATCH v5] mm, dax: fix DAX deadlocks

From: Dave Chinner
Date: Mon Oct 12 2015 - 18:53:37 EST


On Wed, Oct 07, 2015 at 04:58:49PM -0600, Ross Zwisler wrote:
> The following two locking commits in the DAX code:
>
> commit 843172978bb9 ("dax: fix race between simultaneous faults")
> commit 46c043ede471 ("mm: take i_mmap_lock in unmap_mapping_range() for DAX")
>
> introduced a number of deadlocks and other issues which need to be fixed
> for the v4.3 kernel. The list of issues in DAX after these commits (some
> newly introduced by the commits, some preexisting) can be found here:
>
> https://lkml.org/lkml/2015/9/25/602
>
> This undoes most of the changes introduced by those two commits,
> essentially returning us to the DAX locking scheme that was used in v4.2.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>

I've run this through some testing, the deadlocks aren't present and
there don't appear to be any new regressions, so IMO this is fine to
go to Linus.

Tested-by: Dave Chinner <dchinner@xxxxxxxxxx>

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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