In one vmap_block area, there could be three types of regions: region being used which is allocated through vb_alloc(), dirty region which is freed via vb_free() and free region. Among them, only used region has available data. While there's no way to track those used regions currently. Here, add bitmap field used_map into vmap_block, and set/clear it during allocation or freeing regions of vmap_block area. This is a preparatoin for later use. Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> --- mm/vmalloc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ccaa461998f3..5d3fd3e6fe09 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1896,6 +1896,7 @@ struct vmap_block { spinlock_t lock; struct vmap_area *va; unsigned long free, dirty; + DECLARE_BITMAP(used_map, VMAP_BBMAP_BITS); unsigned long dirty_min, dirty_max; /*< dirty range */ struct list_head free_list; struct rcu_head rcu_head; @@ -1972,10 +1973,12 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) vb->va = va; /* At least something should be left free */ BUG_ON(VMAP_BBMAP_BITS <= (1UL << order)); + bitmap_zero(vb->used_map, VMAP_BBMAP_BITS); vb->free = VMAP_BBMAP_BITS - (1UL << order); vb->dirty = 0; vb->dirty_min = VMAP_BBMAP_BITS; vb->dirty_max = 0; + bitmap_set(vb->used_map, 0, (1UL << order)); INIT_LIST_HEAD(&vb->free_list); vb_idx = addr_to_vb_idx(va->va_start); @@ -2081,6 +2084,7 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask) pages_off = VMAP_BBMAP_BITS - vb->free; vaddr = vmap_block_vaddr(vb->va->va_start, pages_off); vb->free -= 1UL << order; + bitmap_set(vb->used_map, pages_off, (1UL << order)); if (vb->free == 0) { spin_lock(&vbq->lock); list_del_rcu(&vb->free_list); @@ -2114,6 +2118,9 @@ static void vb_free(unsigned long addr, unsigned long size) order = get_order(size); offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT; vb = xa_load(&vmap_blocks, addr_to_vb_idx(addr)); + spin_lock(&vb->lock); + bitmap_clear(vb->used_map, offset, (1UL << order)); + spin_unlock(&vb->lock); vunmap_range_noflush(addr, addr + size); -- 2.34.1