On Wed, Dec 23, 2015 at 2:39 PM, NeilBrown <neilb@xxxxxxxx> wrote: > On Thu, Dec 24 2015, Dan Williams wrote: >>> Changing the GFP_NOIO to GFP_ATOMIC in all the calls to >>> dmaengine_get_unmap_data() in crypto/async_tx/ would probably fix the >>> issue... or make it crash even worse :-) >>> >>> Dan: do you have any wisdom here? The xor is using the percpu data in >>> raid5, so it cannot be sleep, but GFP_NOIO allows sleep. >>> Does the code handle failure to get_unmap_data() safely? It looks like >>> it probably does. >> >> Those GFP_NOIO should move to GFP_NOWAIT. We don't want GFP_ATOMIC >> allocations to consume emergency reserves for a performance >> optimization. Longer term async_tx needs to be merged into md >> directly as we can allocate this unmap data statically per-stripe >> rather than per request. This asyntc_tx re-write has been on the todo >> list for years, but never seems to make it to the top. > > So the following maybe? > If I could get an acked-by from you Dan, and a Tested-by: from you > Slava, I'll submit upstream. > > Thanks, > NeilBrown > > From: NeilBrown <neilb@xxxxxxxx> > Date: Thu, 24 Dec 2015 09:35:18 +1100 > Subject: [PATCH] async_tx: use GFP_NOWAIT rather than GFP_IO > > These async_XX functions are called from md/raid5 in an atomic > section, between get_cpu() and put_cpu(), so they must not sleep. > So use GFP_NOWAIT rather than GFP_IO. > > Dan Williams writes: Longer term async_tx needs to be merged into md > directly as we can allocate this unmap data statically per-stripe > rather than per request. > > Reported-by: Stanislav Samsonov <slava@xxxxxxxxxxxxxxxxx> > Signed-off-by: NeilBrown <neilb@xxxxxxxx> Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
