+CC On 1/7/20 3:27 PM, Kirill A. Shutemov wrote: >>>> Option 2: Add a memalloc_nowait_save/restore API to go along >>>> with nofs and noio. That way, we can take the RCU read lock, call >>>> memalloc_nowait_save(), and walk the VMA tree and the page tables in >>>> the current order. There's an increased chance of memory allocation of >>>> page tables failing, so we'll have to risk that and do a retry with the >>>> reference count held on the VMA if we need to sleep to allocate memory. >>>> >>>> Option 3: Variant of 2 where we add GFP flags to the p??_alloc() >>>> functions. >>> >>> I think this is the most reasonable way. If we are low of memory, latency >>> is not on the top of priorities. >> >> You prefer adding GFP flags over adding a memalloc_nowait_save()? > > I don't have strong preference here. I think it's generally a good idea to have the memalloc_() scoping. However, we use the PF_* flags where it now seems 30 out of 32 are used, and MEMALLOC* already occupies 3 of those.
