[PATCH v2 3/6] mm: introduce zone_gup_lock, for dma-pinned pages

2018-07-01 Thread john . hubbard
From: John Hubbard The page->dma_pinned_flags and _count fields require lock protection. A lock at approximately the granularity of the zone_lru_lock is called for, but adding to the locking contention of zone_lru_lock is undesirable, because that is a pre-existing hot spot. Fortunately, these

[PATCH v2 3/6] mm: introduce zone_gup_lock, for dma-pinned pages

2018-07-01 Thread john . hubbard
From: John Hubbard The page->dma_pinned_flags and _count fields require lock protection. A lock at approximately the granularity of the zone_lru_lock is called for, but adding to the locking contention of zone_lru_lock is undesirable, because that is a pre-existing hot spot. Fortunately, these