[dm-devel] Patch "dm: ensure bio submission follows a depth-first tree walk" has been added to the 4.15-stable tree
Mikulas Patocka
mpatocka at redhat.com
Thu Mar 22 13:56:22 UTC 2018
I agree.
The patch "dm: ensure bio submission follows a depth-first tree walk"
doesn't really fix any bug (and it may introduce new bugs), so it isn't
applicable to the stable kernel branches.
The kernel 4.15 and below have a "dm_offload" mechanism that avoids the
possible deadlocks in dm, there is no reason why this should be converted
to the "depth-first tree walk".
Mikulas
On Thu, 22 Mar 2018, Mike Snitzer wrote:
> On Thu, Mar 22 2018 at 9:06am -0400,
> gregkh at linuxfoundation.org <gregkh at linuxfoundation.org> wrote:
>
> >
> > This is a note to let you know that I've just added the patch titled
> >
> > dm: ensure bio submission follows a depth-first tree walk
> >
> > to the 4.15-stable tree which can be found at:
> > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> >
> > The filename of the patch is:
> > dm-ensure-bio-submission-follows-a-depth-first-tree-walk.patch
> > and it can be found in the queue-4.15 subdirectory.
> >
> > If you, or anyone else, feels it should not be added to the stable tree,
> > please let <stable at vger.kernel.org> know about it.
>
> The following applies to 4.14 stable@ too.
>
> I think it very questionable to pull this into stable trees. How'd it
> even elevate to be considered for stable@?
>
> But if you do, you definitely need this additional upstream commit:
> 8dd601fa8317 ("dm: correctly handle chained bios in dec_pending()")
>
> Even with that I'm not excited about supporting some partial backport of
> these changes because there were a lot more related changes -- only
> taking a subset makes these stable@ kernels unicorns.. I deal with
> enough unicorn vendor kernels (but on my terms, with my control over
> what is "supportable"):
>
> Anyway, other related commits are:
> 80cd17578310 dm crypt: remove BIOSET_NEED_RESCUER flag
> c110a4b6e603 dm io: remove BIOSET_NEED_RESCUER flag from bios bioset
> f31c21e4365c dm: remove unused 'num_write_bios' target interface
> 318716ddea08 dm: safely allocate multiple bioset bios
> 4a3f54d94d5c dm: remove BIOSET_NEED_RESCUER based dm_offload infrastructure
> 0776aa0e30aa dm: ensure bio-based DM's bioset and io_pool support targets' maximum IOs
> 3d7f45625a84 dm: fix __send_changing_extent_only() to send first bio and chain remainder
>
> So NAK from me. If others have a compelling argument I'm open to
> considering.
>
> Mike
>
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