On Tue, Mar 07 2017 at 12:05pm -0500, Jens Axboe <ax...@kernel.dk> wrote:
> On 03/07/2017 09:52 AM, Mike Snitzer wrote: > > On Tue, Mar 07 2017 at 3:49am -0500, > > Jack Wang <jinpu.w...@profitbricks.com> wrote: > > > >> > >> > >> On 06.03.2017 21:18, Jens Axboe wrote: > >>> On 03/05/2017 09:40 PM, NeilBrown wrote: > >>>> On Fri, Mar 03 2017, Jack Wang wrote: > >>>>> > >>>>> Thanks Neil for pushing the fix. > >>>>> > >>>>> We can optimize generic_make_request a little bit: > >>>>> - assign bio_list struct hold directly instead init and merge > >>>>> - remove duplicate code > >>>>> > >>>>> I think better to squash into your fix. > >>>> > >>>> Hi Jack, > >>>> I don't object to your changes, but I'd like to see a response from > >>>> Jens first. > >>>> My preference would be to get the original patch in, then other changes > >>>> that build on it, such as this one, can be added. Until the core > >>>> changes lands, any other work is pointless. > >>>> > >>>> Of course if Jens wants a this merged before he'll apply it, I'll > >>>> happily do that. > >>> > >>> I like the change, and thanks for tackling this. It's been a pending > >>> issue for way too long. I do think we should squash Jack's patch > >>> into the original, as it does clean up the code nicely. > >>> > >>> Do we have a proper test case for this, so we can verify that it > >>> does indeed also work in practice? > >>> > >> Hi Jens, > >> > >> I can trigger deadlock with in RAID1 with test below: > >> > >> I create one md with one local loop device and one remote scsi > >> exported by SRP. running fio with mix rw on top of md, force_close > >> session on storage side. mdx_raid1 is wait on free_array in D state, > >> and a lot of fio also in D state in wait_barrier. > >> > >> With the patch from Neil above, I can no longer trigger it anymore. > >> > >> The discussion was in link below: > >> http://www.spinics.net/lists/raid/msg54680.html > > > > In addition to Jack's MD raid test there is a DM snapshot deadlock test, > > albeit unpolished/needy to get running, see: > > https://www.redhat.com/archives/dm-devel/2017-January/msg00064.html > > Can you run this patch with that test, reverting your DM workaround? Yeap, will do. Last time Mikulas tried a similar patch it still deadlocked. But I'll give it a go (likely tomorrow).
