On Thu, Aug 29, 2024 at 4:48 PM Vlastimil Babka <vbabka@xxxxxxx> wrote: > AFAICS: > > - __zone_watermark_unusable_free() for ALLOC_RESERVES (which includes > ALLOC_NON_BLOCK which GFP_ATOMIC allocations have) does not subtract the > reserve_highatomic, so the allocations pass the watermarks > - but in rmqueue_buddy() only ALLOC_OOM is able to fallback into highatomic > - unreserve_highatomic_pageblock() is only called from reclaim and there's > no reclaim for GFP_ATOMIC > > (also worth checking if kswapd even does anything if free > high, but it's > all highatomic, maybe not? so it can't help us here) As far as I can tell we'll wake kswapd but like you said because free > high it thinks the pgdat is balanced. How is the system supposed to recover in this situation? Wait for a non-atomic alloc to fail and enter direct reclaim?
