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A new task_work is queued from task tick >> handler to migrate them in batches. Migration is done >> periodically or if pending number of isolated foios exceeds >> a threshold. > > That means that these pages are effectively unmovable for other purposes > (CMA, compaction, long-term pinning, whatever) until that list was drained. > > Bad. During the last week's MM alignment call on this subject, it was decided not to isolate and batch from fault context and migrate from task_work context like this. However since the amount of time the folios stay in isolated state was bounded both by time(1s in my patchset) and the number of folios isolated, I thought it should be okay, but I may be wrong. Regards, Bharata.