Lots of questions (ie, missing information!) On Wed, 12 Apr 2023 19:59:39 +0000 Pasha Tatashin <pasha.tatashin@xxxxxxxxxx> wrote: > HugeTLB pages have a struct page optimizations where struct pages for tail > pages are freed. However, when HugeTLB pages are destroyed, the memory for > struct pages (vmemmap) need to be allocated again. > > Currently, __GFP_NORETRY flag is used to allocate the memory for vmemmap, > but given that this flag makes very little effort to actually reclaim > memory the returning of huge pages back to the system can be problem. Are there any reports of this happening in the real world? > Lets > use __GFP_RETRY_MAYFAIL instead. This flag is also performs graceful > reclaim without causing ooms, but at least it may perform a few retries, > and will fail only when there is genuinely little amount of unused memory > in the system. If so, does this change help? If the allocation attempt fails, what are the consequences? What are the potential downsides to this change? Why did we choose __GFP_NORETRY in the first place? What happens if we try harder (eg, GFP_KERNEL)?
