[PATCH 0/3] mm: vmalloc: introduce array allocation functions

[PATCH 0/3] mm: vmalloc: introduce array allocation functions

[Paolo Bonzini]

The first patch in this series introduces four array allocation
functions to replace vmalloc(array_size()) and vzalloc(array_size()),
of which Linux has dozens of occurrences.  The Functions take care of
the multiplication and overflow check, result in simpler code and make
it easier for developers to avoid overflow bugs.

The other two patches start to apply the functions in the mm/ and KVM
areas.  In the case of KVM, it is also important to switch from kvcalloc
to __vcalloc; the allocation size is driven by userspace and can be larger
than 4GiB, which has been forbidden by the kv*alloc functions since 5.15.

Paolo

Paolo Bonzini (3):
  mm: vmalloc: introduce array allocation functions
  mm: use vmalloc_array and vcalloc for array allocations
  KVM: use __vcalloc for very large allocations

 arch/powerpc/kvm/book3s_hv_uvmem.c |  2 +-
 arch/x86/kvm/mmu/page_track.c      |  7 +++--
 arch/x86/kvm/x86.c                 |  4 +--
 include/linux/vmalloc.h            |  5 +++
 mm/percpu-stats.c                  |  2 +-
 mm/swap_cgroup.c                   |  4 +--
 mm/util.c                          | 50 ++++++++++++++++++++++++++++++
 virt/kvm/kvm_main.c                |  4 +--
 9 files changed, 66 insertions(+), 12 deletions(-)

-- 
2.31.1

[PATCH 1/3] mm: vmalloc: introduce array allocation functions

[Paolo Bonzini]

Linux has dozens of occurrences of vmalloc(array_size()) and
vzalloc(array_size()).  Allow to simplify the code by providing
vmalloc_array and vcalloc, as well as the underscored variants that let
the caller specify the GFP flags.

Cc: stable@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/linux/vmalloc.h |  5 +++++
 mm/util.c               | 50 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 880227b9f044..d1bbd4fd50c5 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -159,6 +159,11 @@ void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
 		int node, const void *caller) __alloc_size(1);
 void *vmalloc_no_huge(unsigned long size) __alloc_size(1);
 
+extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
+extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2);
+extern void *__vcalloc(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
+extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2);
+
 extern void vfree(const void *addr);
 extern void vfree_atomic(const void *addr);
 
diff --git a/mm/util.c b/mm/util.c
index 7e43369064c8..94475abe54a0 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -647,6 +647,56 @@ void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
 }
 EXPORT_SYMBOL(kvrealloc);
 
+/**
+ * __vmalloc_array - allocate memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ * @flags: the type of memory to allocate (see kmalloc).
+ */
+void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
+{
+	size_t bytes;
+
+	if (unlikely(check_mul_overflow(n, size, &bytes)))
+		return NULL;
+	return __vmalloc(bytes, flags);
+}
+EXPORT_SYMBOL(__vmalloc_array);
+
+/**
+ * vmalloc_array - allocate memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ */
+void *vmalloc_array(size_t n, size_t size)
+{
+	return __vmalloc_array(n, size, GFP_KERNEL);
+}
+EXPORT_SYMBOL(vmalloc_array);
+
+/**
+ * __vcalloc - allocate and zero memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ * @flags: the type of memory to allocate (see kmalloc).
+ */
+void *__vcalloc(size_t n, size_t size, gfp_t flags)
+{
+	return __vmalloc_array(n, size, flags | __GFP_ZERO);
+}
+EXPORT_SYMBOL(__vcalloc);
+
+/**
+ * vcalloc - allocate and zero memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ */
+void *vcalloc(size_t n, size_t size)
+{
+	return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vcalloc);
+
 /* Neutral page->mapping pointer to address_space or anon_vma or other */
 void *page_rmapping(struct page *page)
 {
-- 
2.31.1

Re: [PATCH 1/3] mm: vmalloc: introduce array allocation functions

[Michal Hocko]

On Tue 08-03-22 05:59:16, Paolo Bonzini wrote:
> Linux has dozens of occurrences of vmalloc(array_size()) and
> vzalloc(array_size()).  Allow to simplify the code by providing
> vmalloc_array and vcalloc, as well as the underscored variants that let
> the caller specify the GFP flags.
> 
> Cc: stable@vger.kernel.org
> Cc: linux-mm@kvack.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Seems useful
Acked-by: Michal Hocko <mhocko@suse.com>

Is there any reason you haven't used __alloc_size(1, 2) annotation?

Thanks!
> ---
>  include/linux/vmalloc.h |  5 +++++
>  mm/util.c               | 50 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 55 insertions(+)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 880227b9f044..d1bbd4fd50c5 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -159,6 +159,11 @@ void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
>  		int node, const void *caller) __alloc_size(1);
>  void *vmalloc_no_huge(unsigned long size) __alloc_size(1);
>  
> +extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
> +extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2);
> +extern void *__vcalloc(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
> +extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2);
> +
>  extern void vfree(const void *addr);
>  extern void vfree_atomic(const void *addr);
>  
> diff --git a/mm/util.c b/mm/util.c
> index 7e43369064c8..94475abe54a0 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -647,6 +647,56 @@ void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
>  }
>  EXPORT_SYMBOL(kvrealloc);
>  
> +/**
> + * __vmalloc_array - allocate memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + * @flags: the type of memory to allocate (see kmalloc).
> + */
> +void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
> +{
> +	size_t bytes;
> +
> +	if (unlikely(check_mul_overflow(n, size, &bytes)))
> +		return NULL;
> +	return __vmalloc(bytes, flags);
> +}
> +EXPORT_SYMBOL(__vmalloc_array);
> +
> +/**
> + * vmalloc_array - allocate memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + */
> +void *vmalloc_array(size_t n, size_t size)
> +{
> +	return __vmalloc_array(n, size, GFP_KERNEL);
> +}
> +EXPORT_SYMBOL(vmalloc_array);
> +
> +/**
> + * __vcalloc - allocate and zero memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + * @flags: the type of memory to allocate (see kmalloc).
> + */
> +void *__vcalloc(size_t n, size_t size, gfp_t flags)
> +{
> +	return __vmalloc_array(n, size, flags | __GFP_ZERO);
> +}
> +EXPORT_SYMBOL(__vcalloc);
> +
> +/**
> + * vcalloc - allocate and zero memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + */
> +void *vcalloc(size_t n, size_t size)
> +{
> +	return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
> +}
> +EXPORT_SYMBOL(vcalloc);
> +
>  /* Neutral page->mapping pointer to address_space or anon_vma or other */
>  void *page_rmapping(struct page *page)
>  {
> -- 
> 2.31.1

-- 
Michal Hocko
SUSE Labs

Re: [PATCH 1/3] mm: vmalloc: introduce array allocation functions

[Paolo Bonzini]

On 3/8/22 14:47, Michal Hocko wrote:
> Seems useful
> Acked-by: Michal Hocko<mhocko@suse.com>
> 
> Is there any reason you haven't used __alloc_size(1, 2) annotation?

It's enough to have them in the header:

>> +extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
>> +extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2);
>> +extern void *__vcalloc(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
>> +extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2);

Thanks for the quick review!

Paolo

Re: [PATCH 1/3] mm: vmalloc: introduce array allocation functions

[Michal Hocko]

On Tue 08-03-22 14:55:39, Paolo Bonzini wrote:
> On 3/8/22 14:47, Michal Hocko wrote:
> > Seems useful
> > Acked-by: Michal Hocko<mhocko@suse.com>
> > 
> > Is there any reason you haven't used __alloc_size(1, 2) annotation?
> 
> It's enough to have them in the header:
> 
> > > +extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
> > > +extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2);
> > > +extern void *__vcalloc(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
> > > +extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2);

My bad, I have expected __alloc_size before the function name and simply
haven't noticed it at the end.
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 1/3] mm: vmalloc: introduce array allocation functions

[David Hildenbrand]

On 08.03.22 11:59, Paolo Bonzini wrote:
> Linux has dozens of occurrences of vmalloc(array_size()) and
> vzalloc(array_size()).  Allow to simplify the code by providing
> vmalloc_array and vcalloc, as well as the underscored variants that let
> the caller specify the GFP flags.
> 
> Cc: stable@vger.kernel.org
> Cc: linux-mm@kvack.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

[PATCH 2/3] mm: use vmalloc_array and vcalloc for array allocations

[Paolo Bonzini]

Instead of using array_size or just a multiply, use a function that
takes care of both the multiplication and the overflow checks.

Cc: linux-mm@kvack.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 mm/percpu-stats.c | 2 +-
 mm/swap_cgroup.c  | 4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
index c6bd092ff7a3..e71651cda2de 100644
--- a/mm/percpu-stats.c
+++ b/mm/percpu-stats.c
@@ -144,7 +144,7 @@ static int percpu_stats_show(struct seq_file *m, void *v)
 	spin_unlock_irq(&pcpu_lock);
 
 	/* there can be at most this many free and allocated fragments */
-	buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1)));
+	buffer = vmalloc_array(2 * max_nr_alloc + 1, sizeof(int));
 	if (!buffer)
 		return -ENOMEM;
 
diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index 7f34343c075a..5a9442979a18 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -167,14 +167,12 @@ unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
 int swap_cgroup_swapon(int type, unsigned long max_pages)
 {
 	void *array;
-	unsigned long array_size;
 	unsigned long length;
 	struct swap_cgroup_ctrl *ctrl;
 
 	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
-	array_size = length * sizeof(void *);
 
-	array = vzalloc(array_size);
+	array = vcalloc(length, sizeof(void *));
 	if (!array)
 		goto nomem;
 
-- 
2.31.1

Re: [PATCH 2/3] mm: use vmalloc_array and vcalloc for array allocations

[Michal Hocko]

On Tue 08-03-22 05:59:17, Paolo Bonzini wrote:
> Instead of using array_size or just a multiply, use a function that
> takes care of both the multiplication and the overflow checks.
> 
> Cc: linux-mm@kvack.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.com>

The resulting code is easier to read indeed.

> ---
>  mm/percpu-stats.c | 2 +-
>  mm/swap_cgroup.c  | 4 +---
>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
> index c6bd092ff7a3..e71651cda2de 100644
> --- a/mm/percpu-stats.c
> +++ b/mm/percpu-stats.c
> @@ -144,7 +144,7 @@ static int percpu_stats_show(struct seq_file *m, void *v)
>  	spin_unlock_irq(&pcpu_lock);
>  
>  	/* there can be at most this many free and allocated fragments */
> -	buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1)));
> +	buffer = vmalloc_array(2 * max_nr_alloc + 1, sizeof(int));
>  	if (!buffer)
>  		return -ENOMEM;
>  
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index 7f34343c075a..5a9442979a18 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -167,14 +167,12 @@ unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
>  int swap_cgroup_swapon(int type, unsigned long max_pages)
>  {
>  	void *array;
> -	unsigned long array_size;
>  	unsigned long length;
>  	struct swap_cgroup_ctrl *ctrl;
>  
>  	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
> -	array_size = length * sizeof(void *);
>  
> -	array = vzalloc(array_size);
> +	array = vcalloc(length, sizeof(void *));
>  	if (!array)
>  		goto nomem;
>  
> -- 
> 2.31.1
> 
> 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH 2/3] mm: use vmalloc_array and vcalloc for array allocations

[David Hildenbrand]

On 08.03.22 11:59, Paolo Bonzini wrote:
> Instead of using array_size or just a multiply, use a function that
> takes care of both the multiplication and the overflow checks.
> 
> Cc: linux-mm@kvack.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb

Re: [PATCH 2/3] mm: use vmalloc_array and vcalloc for array allocations

[Dennis Zhou]

Hello,

On Tue, Mar 08, 2022 at 05:59:17AM -0500, Paolo Bonzini wrote:
> Instead of using array_size or just a multiply, use a function that
> takes care of both the multiplication and the overflow checks.
> 
> Cc: linux-mm@kvack.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  mm/percpu-stats.c | 2 +-
>  mm/swap_cgroup.c  | 4 +---
>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
> index c6bd092ff7a3..e71651cda2de 100644
> --- a/mm/percpu-stats.c
> +++ b/mm/percpu-stats.c
> @@ -144,7 +144,7 @@ static int percpu_stats_show(struct seq_file *m, void *v)
>  	spin_unlock_irq(&pcpu_lock);
>  
>  	/* there can be at most this many free and allocated fragments */
> -	buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1)));
> +	buffer = vmalloc_array(2 * max_nr_alloc + 1, sizeof(int));
>  	if (!buffer)
>  		return -ENOMEM;
>  
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index 7f34343c075a..5a9442979a18 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -167,14 +167,12 @@ unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
>  int swap_cgroup_swapon(int type, unsigned long max_pages)
>  {
>  	void *array;
> -	unsigned long array_size;
>  	unsigned long length;
>  	struct swap_cgroup_ctrl *ctrl;
>  
>  	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
> -	array_size = length * sizeof(void *);
>  
> -	array = vzalloc(array_size);
> +	array = vcalloc(length, sizeof(void *));
>  	if (!array)
>  		goto nomem;
>  
> -- 
> 2.31.1
> 

Acked-by: Dennis Zhou <dennis@kernel.org>

Thanks,
Dennis

[PATCH 3/3] KVM: use vcalloc/__vcalloc for very large allocations

[Paolo Bonzini]

Allocations whose size is related to the memslot size can be arbitrarily
large.  Do not use kvzalloc/kvcalloc, as those are limited to "not crazy"
sizes that fit in 32 bits.  Now that it is available, they can use either
vcalloc or __vcalloc, the latter if accounting is required.

Cc: stable@vger.kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/powerpc/kvm/book3s_hv_uvmem.c | 2 +-
 arch/x86/kvm/mmu/page_track.c      | 7 ++++---
 arch/x86/kvm/x86.c                 | 4 ++--
 virt/kvm/kvm_main.c                | 4 ++--
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index e414ca44839f..be441403925b 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -251,7 +251,7 @@ int kvmppc_uvmem_slot_init(struct kvm *kvm, const struct kvm_memory_slot *slot)
 	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
-	p->pfns = vzalloc(array_size(slot->npages, sizeof(*p->pfns)));
+	p->pfns = vcalloc(slot->npages, sizeof(*p->pfns));
 	if (!p->pfns) {
 		kfree(p);
 		return -ENOMEM;
diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 68eb1fb548b6..2e09d1b6249f 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -47,8 +47,8 @@ int kvm_page_track_create_memslot(struct kvm *kvm,
 			continue;
 
 		slot->arch.gfn_track[i] =
-			kvcalloc(npages, sizeof(*slot->arch.gfn_track[i]),
-				 GFP_KERNEL_ACCOUNT);
+			__vcalloc(npages, sizeof(*slot->arch.gfn_track[i]),
+				  GFP_KERNEL_ACCOUNT);
 		if (!slot->arch.gfn_track[i])
 			goto track_free;
 	}
@@ -75,7 +75,8 @@ int kvm_page_track_write_tracking_alloc(struct kvm_memory_slot *slot)
 	if (slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE])
 		return 0;
 
-	gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track), GFP_KERNEL_ACCOUNT);
+	gfn_track = __vcalloc(slot->npages, sizeof(*gfn_track),
+			      GFP_KERNEL_ACCOUNT);
 	if (gfn_track == NULL)
 		return -ENOMEM;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f79bf4552082..4fa4d8269e5b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11838,7 +11838,7 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages)
 		if (slot->arch.rmap[i])
 			continue;
 
-		slot->arch.rmap[i] = kvcalloc(lpages, sz, GFP_KERNEL_ACCOUNT);
+		slot->arch.rmap[i] = __vcalloc(lpages, sz, GFP_KERNEL_ACCOUNT);
 		if (!slot->arch.rmap[i]) {
 			memslot_rmap_free(slot);
 			return -ENOMEM;
@@ -11875,7 +11875,7 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm,
 
 		lpages = __kvm_mmu_slot_lpages(slot, npages, level);
 
-		linfo = kvcalloc(lpages, sizeof(*linfo), GFP_KERNEL_ACCOUNT);
+		linfo = __vcalloc(lpages, sizeof(*linfo), GFP_KERNEL_ACCOUNT);
 		if (!linfo)
 			goto out_free;
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c941b97fa133..a5726099df67 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1274,9 +1274,9 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
  */
 static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot)
 {
-	unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot);
+	unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot);
 
-	memslot->dirty_bitmap = kvzalloc(dirty_bytes, GFP_KERNEL_ACCOUNT);
+	memslot->dirty_bitmap = __vcalloc(2, dirty_bytes, GFP_KERNEL_ACCOUNT);
 	if (!memslot->dirty_bitmap)
 		return -ENOMEM;
 
-- 
2.31.1

Re: [PATCH 3/3] KVM: use vcalloc/__vcalloc for very large allocations

[David Hildenbrand]

On 08.03.22 11:59, Paolo Bonzini wrote:
> Allocations whose size is related to the memslot size can be arbitrarily
> large.  Do not use kvzalloc/kvcalloc, as those are limited to "not crazy"
> sizes that fit in 32 bits.  Now that it is available, they can use either
> vcalloc or __vcalloc, the latter if accounting is required.
> 
> Cc: stable@vger.kernel.org
> Cc: kvm@vger.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")

?

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb

Re: [PATCH 3/3] KVM: use vcalloc/__vcalloc for very large allocations

[Andrew Morton]

On Tue,  8 Mar 2022 05:59:18 -0500 Paolo Bonzini <pbonzini@redhat.com> wrote:

> Allocations whose size is related to the memslot size can be arbitrarily
> large.  Do not use kvzalloc/kvcalloc, as those are limited to "not crazy"
> sizes that fit in 32 bits.  Now that it is available, they can use either
> vcalloc or __vcalloc, the latter if accounting is required.
> 
> Cc: stable@vger.kernel.org

Please fully describe the end user visible runtime effects when
proposing a -stable backport.  And when not proposing a -stable
backport, come to that...