Through vmalloc API, a virtual kernel area is reserved for physical
address mapping. And vmap_area is used to track them, and vm_struct is
allocated to associate with the vmap_area to store more information and
passed out.
However, area reserved via vm_map_ram() is an exception. It doesn't have
vm_struct to associate with vmap_area. And we can't simply recognize the
vm_map_ram areas with '->vm == NULL' because the normal freeing path will
set va->vm = NULL before unmapping, please see function remove_vm_area().
Meanwhile, there are two types of vm_map_ram area. One is the whole
vmap_area being reserved and mapped at one time; the other is the
whole vmap_area with VMAP_BLOCK_SIZE size being reserved, while mapped
into split regions with smaller size several times.
To mark the area reserved through vm_map_ram(), add flags into the
union field of struct vmap_area to reuse the space since that union
space is free anyway if it's vm_map_ram area.
This is a preparatoin for later use.
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
include/linux/vmalloc.h | 1 +
mm/vmalloc.c | 17 ++++++++++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 096d48aa3437..b739a60b73da 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -75,6 +75,7 @@ struct vmap_area {
union {
unsigned long subtree_max_size; /* in "free" tree */
struct vm_struct *vm; /* in "busy" tree */
+ unsigned long flags; /* mark type of vm_map_ram area */
};
};
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5d3fd3e6fe09..41d82dc07e13 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1815,6 +1815,7 @@ static void free_vmap_area_noflush(struct vmap_area *va)
spin_lock(&vmap_area_lock);
unlink_va(va, &vmap_area_root);
+ va->flags = 0;
spin_unlock(&vmap_area_lock);
nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
@@ -1887,6 +1888,9 @@ struct vmap_area *find_vmap_area(unsigned long addr)
#define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE)
+#define VMAP_RAM 0x1
+#define VMAP_BLOCK 0x2
+
struct vmap_block_queue {
spinlock_t lock;
struct list_head free;
@@ -1967,6 +1971,9 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
kfree(vb);
return ERR_CAST(va);
}
+ spin_lock(&vmap_area_lock);
+ va->flags = VMAP_RAM|VMAP_BLOCK;
+ spin_unlock(&vmap_area_lock);
vaddr = vmap_block_vaddr(va->va_start, 0);
spin_lock_init(&vb->lock);
@@ -2229,8 +2236,12 @@ void vm_unmap_ram(const void *mem, unsigned int count)
return;
}
- va = find_vmap_area(addr);
+ spin_lock(&vmap_area_lock);
+ va = __find_vmap_area((unsigned long)addr, &vmap_area_root);
BUG_ON(!va);
+ if (va)
+ va->flags &= ~VMAP_RAM;
+ spin_unlock(&vmap_area_lock);
debug_check_no_locks_freed((void *)va->va_start,
(va->va_end - va->va_start));
free_unmap_vmap_area(va);
@@ -2269,6 +2280,10 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node)
if (IS_ERR(va))
return NULL;
+ spin_lock(&vmap_area_lock);
+ va->flags = VMAP_RAM;
+ spin_unlock(&vmap_area_lock);
+
addr = va->va_start;
mem = (void *)addr;
}
--
2.34.1
