On Thu 06-04-17 09:33:44, Adrian Hunter wrote: > On 05/04/17 14:39, Vlastimil Babka wrote: > > On 04/05/2017 01:36 PM, Richard Weinberger wrote: > >> Michal, > >> > >> Am 05.04.2017 um 13:31 schrieb Michal Hocko: > >>> On Wed 05-04-17 09:47:00, Vlastimil Babka wrote: > >>>> Nandsim has own functions set_memalloc() and clear_memalloc() for robust > >>>> setting and clearing of PF_MEMALLOC. Replace them by the new generic helpers. > >>>> No functional change. > >>> > >>> This one smells like an abuser. Why the hell should read/write path > >>> touch memory reserves at all! > >> > >> Could be. Let's ask Adrian, AFAIK he wrote that code. > >> Adrian, can you please clarify why nandsim needs to play with PF_MEMALLOC? > > > > I was thinking about it and concluded that since the simulator can be > > used as a block device where reclaimed pages go to, writing the data out > > is a memalloc operation. Then reading can be called as part of r-m-w > > cycle, so reading as well. > > IIRC it was to avoid getting stuck with nandsim waiting on memory reclaim > and memory reclaim waiting on nandsim. I've got lost in the indirection. Could you describe how would reclaim get stuck waiting on these paths please? -- Michal Hocko SUSE Labs
