diff mbox series

[v3,2/7] mm/vmalloc.c: add flags to mark vm_map_ram area

Message ID 20230113031921.64716-3-bhe@redhat.com
State New
Headers
Series mm/vmalloc.c: allow vread() to read out vm_map_ram areas |

Commit Message

Baoquan He Jan. 13, 2023, 3:19 a.m. UTC 
  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.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/vmalloc.h |  1 +
 mm/vmalloc.c            | 16 ++++++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

Comments

Uladzislau Rezki Jan. 16, 2023, 11:42 a.m. UTC | #1 
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.
> 
> 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
> 
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

--
Uladzislau Rezki
Lorenzo Stoakes Jan. 16, 2023, 12:23 p.m. UTC | #2 
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 :)

> 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>
Baoquan He Jan. 18, 2023, 2:13 a.m. UTC | #3 
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>
>
diff mbox series

Patch

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;