On 2/27/25 11:24, Baoquan He wrote: >> I guess the issue doesn't happen in practice. In any case it's out of scope >> of the reverted commit and the revert. > It could happen on arm64 because arm64 only has ZONE_DMA by default and > its boundary is not fixed. I saw all zones are ZONE_DMA on arm64, I > guess it could be easier to see a arm64 system which only has ZONE_DMA > on node 0 and ZONE_NORMAL/MOVABLE on other nodes. Does it mean the ZONE_DMA is rather large then on arm64 then? In that case things probably works fine even if no protection is applied to it. The x86 ones are small and thus need(ed) it much more. So I don't think we proactively need to change anything unless there are known issues observed in practice. Another reason to avoid the effort is that hopefully we'll get rid of the DMA zones anyway? They don't work all that well anyway in modern times. Ccing Petr for awareness (due to his recent LPC talk about this topic)
