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    SubjectRe: [PATCH v3 2/7] mm/vmalloc.c: add flags to mark vm_map_ram area
    On 01/16/23 at 12:23pm, Lorenzo Stoakes wrote:
    > On Fri, Jan 13, 2023 at 11:19:16AM +0800, Baoquan He wrote:
    > > Through vmalloc API, a virtual kernel area is reserved for physical
    > > address mapping. And vmap_area is used to track them, while 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 recognize the
    > > vmap_area with '->vm == NULL' as a vm_map_ram() area because the normal
    > > freeing path will set va->vm = NULL before unmapping, please see
    > > function remove_vm_area().
    > >
    > > Meanwhile, there are two kinds of handling for vm_map_ram area. One is
    > > the whole vmap_area being reserved and mapped at one time through
    > > vm_map_area() interface; the other is the whole vmap_area with
    > > VMAP_BLOCK_SIZE size being reserved, while mapped into split regions
    > > with smaller size via vb_alloc().
    > >
    > > To mark the area reserved through vm_map_ram(), add flags field into
    > > struct vmap_area. Bit 0 indicates this is vm_map_ram area created
    > > through vm_map_ram() interface, while bit 1 marks out the type of
    > > vm_map_ram area which makes use of vmap_block to manage split regions
    > > via vb_alloc/free().
    > >
    > > This is a preparatoin for later use.
    > >
    >
    > Small typo here :)

    Good catch, will fix it.

    >
    > > Signed-off-by: Baoquan He <bhe@redhat.com>
    > > ---
    > > include/linux/vmalloc.h | 1 +
    > > mm/vmalloc.c | 16 ++++++++++++----
    > > 2 files changed, 13 insertions(+), 4 deletions(-)
    > >
    > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
    > > index 096d48aa3437..69250efa03d1 100644
    > > --- a/include/linux/vmalloc.h
    > > +++ b/include/linux/vmalloc.h
    > > @@ -76,6 +76,7 @@ struct vmap_area {
    > > 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 */
    > > };
    > >
    > > /* archs that select HAVE_ARCH_HUGE_VMAP should override one or more of these */
    > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
    > > index d6ff058ef4d0..ab4825050b5c 100644
    > > --- a/mm/vmalloc.c
    > > +++ b/mm/vmalloc.c
    > > @@ -1589,7 +1589,8 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node)
    > > static struct vmap_area *alloc_vmap_area(unsigned long size,
    > > unsigned long align,
    > > unsigned long vstart, unsigned long vend,
    > > - int node, gfp_t gfp_mask)
    > > + int node, gfp_t gfp_mask,
    > > + unsigned long va_flags)
    > > {
    > > struct vmap_area *va;
    > > unsigned long freed;
    > > @@ -1635,6 +1636,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
    > > va->va_start = addr;
    > > va->va_end = addr + size;
    > > va->vm = NULL;
    > > + va->flags = va_flags;
    > >
    > > spin_lock(&vmap_area_lock);
    > > insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
    > > @@ -1913,6 +1915,10 @@ static struct vmap_area *find_unlink_vmap_area(unsigned long addr)
    > >
    > > #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE)
    > >
    > > +#define VMAP_RAM 0x1 /* indicates vm_map_ram area*/
    > > +#define VMAP_BLOCK 0x2 /* mark out the vmap_block sub-type*/
    > > +#define VMAP_FLAGS_MASK 0x3
    > > +
    > > struct vmap_block_queue {
    > > spinlock_t lock;
    > > struct list_head free;
    > > @@ -1988,7 +1994,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
    > >
    > > va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
    > > VMALLOC_START, VMALLOC_END,
    > > - node, gfp_mask);
    > > + node, gfp_mask,
    > > + VMAP_RAM|VMAP_BLOCK);
    > > if (IS_ERR(va)) {
    > > kfree(vb);
    > > return ERR_CAST(va);
    > > @@ -2297,7 +2304,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node)
    > > } else {
    > > struct vmap_area *va;
    > > va = alloc_vmap_area(size, PAGE_SIZE,
    > > - VMALLOC_START, VMALLOC_END, node, GFP_KERNEL);
    > > + VMALLOC_START, VMALLOC_END,
    > > + node, GFP_KERNEL, VMAP_RAM);
    > > if (IS_ERR(va))
    > > return NULL;
    > >
    > > @@ -2537,7 +2545,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
    > > if (!(flags & VM_NO_GUARD))
    > > size += PAGE_SIZE;
    > >
    > > - va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
    > > + va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0);
    > > if (IS_ERR(va)) {
    > > kfree(area);
    > > return NULL;
    > > --
    > > 2.34.1
    > >
    >
    > Other than that typo,
    >
    > Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
    >

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