mm/vmalloc: get rid of dirty bitmap inside vmap_block structure
In original implementation of vm_map_ram made by Nick Piggin there were two bitmaps: alloc_map and dirty_map. None of them were used as supposed to be: finding a suitable free hole for next allocation in block. vm_map_ram allocates space sequentially in block and on free call marks pages as dirty, so freed space can't be reused anymore. Actually it would be very interesting to know the real meaning of those bitmaps, maybe implementation was incomplete, etc. But long time ago Zhang Yanfei removed alloc_map by these two commits: mm/vmalloc.c: remove dead code in vb_alloc 3fcd76e8 mm/vmalloc.c: remove alloc_map from vmap_block b8e748b6 In this patch I replaced dirty_map with two range variables: dirty min and max. These variables store minimum and maximum position of dirty space in a block, since we need only to know the dirty range, not exact position of dirty p...
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