Hi Maxime, > Von: linux-raid-ow...@vger.kernel.org > [linux-raid-ow...@vger.kernel.org]" im Auftrag von "Maxime Ripard > [maxime.rip...@free-electrons.com] > Gesendet: Donnerstag, 7. Mai 2015 14:57 > An: Neil Brown; Shaohua Li > Cc: linux-r...@vger.kernel.org; linux-kernel@vger.kernel.org; Lior Amsalem; > Thomas Petazzoni; Gregory Clement; Boris Brezillon > Betreff: Possible RAID6 regression with ASYNC_TX_DMA enabled in 4.1 > > Hi, > > I'm currently trying to add support for the PQ operations on the > marvell XOR engine, in dmaengine, obviously to be able to use async_tx > to offload these operations. > > I'm testing these patches with a RAID6 array with 4 disks. > > However, since the commit 59fc630b8b5f ("RAID5: batch adjacent full > stripe write", every write to that array fails with the following > stacktrace. > > http://code.bulix.org/eh8iew-88342?raw
I don't know if it might be related. I added support for RAID6 Read-Modify-Write in software XOR with some patches. The following commit mangles some lines in async_pq.c: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/? id=584acdd49cd2472ca0f5a06adbe979db82d0b4af I introduced a new flag ASYNC_TX_PQ_XOR_DST that notifies the async layer that we want to do a XOR syndrome operation instead of a full calculation. This will enforce the software path because I guessed that hardware does not support that case. Without hardware to check I might have missed some checks in the async layer. In the upper layer ops_run_reconstruct6 will set the flag if we determined that rmw is faster than rcw. Can you check if rmw_level=0 fixes the issue. See: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/? id=d06f191f8ecaef4d524e765fdb455f96392fbd42 > It seems to be generated by that warning here: > > http://lxr.free-electrons.com/source/crypto/async_tx/async_tx.c#L173 > > And indeed, if we dump the status of depend_tx here, it's already been > acked. > > That doesn't happen if ASYNC_TX_DMA is disabled, hence using the > software version of it, instead of relying on our XOR engine. It > doesn't happen on any commit prior to the one mentionned above, with > the exact same changes applied. These changes are meant to be > contributed, so I can definitely push them somewhere if needed. > > I don't really know where to look for though, the change that is > causing this is probably the change in ops_run_reconstruct6, but I'm > not sure that this partial revert alone would work with regard to the > rest of the patch. > > Maxime Markus
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