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 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 via vb_alloc().

To mark the area reserved through vm_map_ram(), add flags field into
struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area,
while bit 1 indicates whether it's a vmap_block type of vm_map_ram
area.

This is a preparatoin for later use.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/vmalloc.h |  1 +
 mm/vmalloc.c            | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

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 5d3fd3e6fe09..d6f376060d83 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 +1888,10 @@ 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
+#define VMAP_FLAGS_MASK		0x3
+
 struct vmap_block_queue {
 	spinlock_t lock;
 	struct list_head free;
@@ -1967,6 +1972,9 @@ 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 +2237,12 @@ 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 +2281,10 @@ 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

> 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 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 via vb_alloc().
> 
> To mark the area reserved through vm_map_ram(), add flags field into
> struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area,
> while bit 1 indicates whether it's a vmap_block type of vm_map_ram
> area.
> 
> This is a preparatoin for later use.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/vmalloc.h |  1 +
>  mm/vmalloc.c            | 18 +++++++++++++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> 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 5d3fd3e6fe09..d6f376060d83 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);
>  
This is not a good place to set flags to zero. It looks to me like
corner and kind of specific.


>  	nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
> @@ -1887,6 +1888,10 @@ 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
> +#define VMAP_FLAGS_MASK		0x3
> +
>  struct vmap_block_queue {
>  	spinlock_t lock;
>  	struct list_head free;
> @@ -1967,6 +1972,9 @@ 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);
>
The per-cpu code was created as a fast per-cpu allocator because of high
vmalloc lock contention. If possible we should avoid of locking of the
vmap_area_lock. Because it has a high contention.

>  
>  	vaddr = vmap_block_vaddr(va->va_start, 0);
>  	spin_lock_init(&vb->lock);
> @@ -2229,8 +2237,12 @@ 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 +2281,10 @@ 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);
> +
>
Same here.

--
Uladzislau Rezki

On 12/05/22 at 01:56pm, Uladzislau Rezki 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 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 via vb_alloc().
> > 
> > To mark the area reserved through vm_map_ram(), add flags field into
> > struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area,
> > while bit 1 indicates whether it's a vmap_block type of vm_map_ram
> > area.
> > 
> > This is a preparatoin for later use.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  include/linux/vmalloc.h |  1 +
> >  mm/vmalloc.c            | 18 +++++++++++++++++-
> >  2 files changed, 18 insertions(+), 1 deletion(-)
> > 
> > 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 5d3fd3e6fe09..d6f376060d83 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);
> >  
> This is not a good place to set flags to zero. It looks to me like
> corner and kind of specific.

Thanks for reviewing.

Here, I thought to clear VMAP_RAM|VMAP_BLOCK on vmap->flags when free
the vmap_block. I didn't find a good place to do the clearing. When we
call free_vmap_block(), we either come from purge_fragmented_blocks(),
or from vb_free(). In vb_free(), it will call free_vmap_block() when
the whole vmap_block is dirty. In purge_fragmented_blocks(), it will
try to purge all vmap_block which only has dirty or free regions.
For both of above functions, they will call free_vmap_block() when
there's no being used region in the vmap_block.

  purge_fragmented_blocks()
  vb_free()
    -->free_vmap_block()

So seems we don't need to clear the VMAP_RAM|VMAP_BLOCK on vmap->flags
because there's no mapping existed in the vmap_block. The consequent
free_vmap_block() will remove the relevant vmap_area from vmap_area_list
and vmap_area_root tree.

So I plan to remove code change in this place.
> 
> 
> >  	nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
> > @@ -1887,6 +1888,10 @@ 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
> > +#define VMAP_FLAGS_MASK		0x3
> > +
> >  struct vmap_block_queue {
> >  	spinlock_t lock;
> >  	struct list_head free;
> > @@ -1967,6 +1972,9 @@ 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);
> >
> The per-cpu code was created as a fast per-cpu allocator because of high
> vmalloc lock contention. If possible we should avoid of locking of the
> vmap_area_lock. Because it has a high contention.

Fair enough. I made below draft patch to address the concern. By
adding argument va_flags to alloc_vmap_area(), we can pass the 
vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags.
With this, we don't need add extra action to acquire vmap_area_root lock
and do the flags setting. Is it OK to you?

From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@redhat.com>
Date: Wed, 7 Dec 2022 11:08:14 +0800
Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags

With this change, we can pass and set vmap_area->flags for vm_map_ram area
in alloc_vmap_area(). Then no extra action need be added to acquire
vmap_area_lock when doing the vmap_area->flags setting.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 mm/vmalloc.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ccaa461998f3..d74eddec352f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1586,7 +1586,9 @@ 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;
@@ -1630,6 +1632,7 @@ 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);
@@ -1961,7 +1964,8 @@ 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);
@@ -2258,7 +2262,8 @@ 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|VMAP_BLOCK);
 		if (IS_ERR(va))
 			return NULL;
 
@@ -2498,7 +2503,7 @@ 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

On Wed, Dec 07, 2022 at 04:03:41PM +0800, Baoquan He wrote:
> On 12/05/22 at 01:56pm, Uladzislau Rezki 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 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 via vb_alloc().
> > > 
> > > To mark the area reserved through vm_map_ram(), add flags field into
> > > struct vmap_area. Bit 0 indicates whether it's a vm_map_ram area,
> > > while bit 1 indicates whether it's a vmap_block type of vm_map_ram
> > > area.
> > > 
> > > This is a preparatoin for later use.
> > > 
> > > Signed-off-by: Baoquan He <bhe@redhat.com>
> > > ---
> > >  include/linux/vmalloc.h |  1 +
> > >  mm/vmalloc.c            | 18 +++++++++++++++++-
> > >  2 files changed, 18 insertions(+), 1 deletion(-)
> > > 
> > > 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 5d3fd3e6fe09..d6f376060d83 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);
> > >  
> > This is not a good place to set flags to zero. It looks to me like
> > corner and kind of specific.
> 
> Thanks for reviewing.
> 
> Here, I thought to clear VMAP_RAM|VMAP_BLOCK on vmap->flags when free
> the vmap_block. I didn't find a good place to do the clearing. When we
> call free_vmap_block(), we either come from purge_fragmented_blocks(),
> or from vb_free(). In vb_free(), it will call free_vmap_block() when
> the whole vmap_block is dirty. In purge_fragmented_blocks(), it will
> try to purge all vmap_block which only has dirty or free regions.
> For both of above functions, they will call free_vmap_block() when
> there's no being used region in the vmap_block.
> 
>   purge_fragmented_blocks()
>   vb_free()
>     -->free_vmap_block()
> 
> So seems we don't need to clear the VMAP_RAM|VMAP_BLOCK on vmap->flags
> because there's no mapping existed in the vmap_block. The consequent
> free_vmap_block() will remove the relevant vmap_area from vmap_area_list
> and vmap_area_root tree.
> 
> So I plan to remove code change in this place.
> > 
> > 
> > >  	nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
> > > @@ -1887,6 +1888,10 @@ 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
> > > +#define VMAP_FLAGS_MASK		0x3
> > > +
> > >  struct vmap_block_queue {
> > >  	spinlock_t lock;
> > >  	struct list_head free;
> > > @@ -1967,6 +1972,9 @@ 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);
> > >
> > The per-cpu code was created as a fast per-cpu allocator because of high
> > vmalloc lock contention. If possible we should avoid of locking of the
> > vmap_area_lock. Because it has a high contention.
> 
> Fair enough. I made below draft patch to address the concern. By
> adding argument va_flags to alloc_vmap_area(), we can pass the 
> vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags.
> With this, we don't need add extra action to acquire vmap_area_root lock
> and do the flags setting. Is it OK to you?
> 
> From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001
> From: Baoquan He <bhe@redhat.com>
> Date: Wed, 7 Dec 2022 11:08:14 +0800
> Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags
> 
> With this change, we can pass and set vmap_area->flags for vm_map_ram area
> in alloc_vmap_area(). Then no extra action need be added to acquire
> vmap_area_lock when doing the vmap_area->flags setting.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  mm/vmalloc.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ccaa461998f3..d74eddec352f 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1586,7 +1586,9 @@ 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;
> @@ -1630,6 +1632,7 @@ 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);
> @@ -1961,7 +1964,8 @@ 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);
> @@ -2258,7 +2262,8 @@ 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|VMAP_BLOCK);
>  		if (IS_ERR(va))
>  			return NULL;
>  
> @@ -2498,7 +2503,7 @@ 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
> 
Yes, this is better than it was before. Adding an extra parameter makes
it more valid and logical.

--
Uladzislau Rezki

On 12/08/22 at 08:52pm, Uladzislau Rezki wrote:
> On Wed, Dec 07, 2022 at 04:03:41PM +0800, Baoquan He wrote:
......
> > > > @@ -1967,6 +1972,9 @@ 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);
> > > >
> > > The per-cpu code was created as a fast per-cpu allocator because of high
> > > vmalloc lock contention. If possible we should avoid of locking of the
> > > vmap_area_lock. Because it has a high contention.
> > 
> > Fair enough. I made below draft patch to address the concern. By
> > adding argument va_flags to alloc_vmap_area(), we can pass the 
> > vm_map_ram flags into alloc_vmap_area and filled into vmap_area->flags.
> > With this, we don't need add extra action to acquire vmap_area_root lock
> > and do the flags setting. Is it OK to you?
> > 
> > From 115f6080b339d0cf9dd20c5f6c0d3121f6b22274 Mon Sep 17 00:00:00 2001
> > From: Baoquan He <bhe@redhat.com>
> > Date: Wed, 7 Dec 2022 11:08:14 +0800
> > Subject: [PATCH] mm/vmalloc: change alloc_vmap_area() to pass in va_flags
> > 
> > With this change, we can pass and set vmap_area->flags for vm_map_ram area
> > in alloc_vmap_area(). Then no extra action need be added to acquire
> > vmap_area_lock when doing the vmap_area->flags setting.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  mm/vmalloc.c | 13 +++++++++----
> >  1 file changed, 9 insertions(+), 4 deletions(-)
> > 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index ccaa461998f3..d74eddec352f 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -1586,7 +1586,9 @@ 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;
> > @@ -1630,6 +1632,7 @@ 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);
> > @@ -1961,7 +1964,8 @@ 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);
> > @@ -2258,7 +2262,8 @@ 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|VMAP_BLOCK);
> >  		if (IS_ERR(va))
> >  			return NULL;
> >  
> > @@ -2498,7 +2503,7 @@ 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
> > 
> Yes, this is better than it was before. Adding an extra parameter makes
> it more valid and logical.

That's great. I will add this in v2.