On Mon 25-06-18 10:42:30, Mikulas Patocka wrote: > > > On Mon, 25 Jun 2018, Michal Hocko wrote: > > > > And the throttling in dm-bufio prevents kswapd from making forward > > > progress, causing this situation... > > > > Which is what we have PF_THROTTLE_LESS for. Geez, do we have to go in > > circles like that? Are you even listening? > > > > [...] > > > > > And so what do you want to do to prevent block drivers from sleeping? > > > > use the existing means we have. > > -- > > Michal Hocko > > SUSE Labs > > So - do you want this patch? > > There is no behavior difference between changing the allocator (so that it > implies PF_THROTTLE_LESS for block drivers) and chaning all the block > drivers to explicitly set PF_THROTTLE_LESS. As long as you can reliably detect those users. And using gfp_mask is about the worst way to achieve that because users tend to be creative when it comes to using gfp mask. PF_THROTTLE_LESS in general is a way to tell the allocator that _you_ are the one to help the reclaim by cleaning data. > But if you insist that the allocator can't be changed, we have to repeat > the same code over and over again in the block drivers. I am not familiar with the patched code but mempool change at least makes sense (bvec_alloc seems to fallback to mempool which then makes sense as well). If others in md/ do the same thing I would just use current_restore_flags rather than open code it. Thanks! -- Michal Hocko SUSE Labs -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
