include/linux/highmem.h | 8 +------- mm/huge_memory.c | 3 ++- mm/internal.h | 6 ++++++ mm/memory.c | 3 ++- 4 files changed, 11 insertions(+), 9 deletions(-)
Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
init_on_free=1 boot options") forces allocated page to be zeroed in
post_alloc_hook() when init_on_alloc=1.
For order-0 folios, if arch does not define
vma_alloc_zeroed_movable_folio(), the default implementation again zeros
the page return from the buddy allocator. So the page is zeroed twice.
Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
define their own vma_alloc_zeroed_movable_folio().
For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
zero the folio again. Fix it by calling folio_zero_user() only if
init_on_alloc is set. All arch are impacted.
Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
include/linux/highmem.h | 8 +-------
mm/huge_memory.c | 3 ++-
mm/internal.h | 6 ++++++
mm/memory.c | 3 ++-
4 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index bec9bd715acf..6e452bd8e7e3 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -224,13 +224,7 @@ static inline
struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
unsigned long vaddr)
{
- struct folio *folio;
-
- folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
- if (folio)
- clear_user_highpage(&folio->page, vaddr);
-
- return folio;
+ return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
}
#endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 82f464865570..5dcbea96edb7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
}
folio_throttle_swaprate(folio, gfp);
- folio_zero_user(folio, addr);
+ if (!alloc_zeroed())
+ folio_zero_user(folio, addr);
/*
* The memory barrier inside __folio_mark_uptodate makes sure that
* folio_zero_user writes become visible before the set_pmd_at()
diff --git a/mm/internal.h b/mm/internal.h
index 906da6280c2d..508f7802dd2b 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1233,6 +1233,12 @@ void touch_pud(struct vm_area_struct *vma, unsigned long addr,
void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, bool write);
+static inline bool alloc_zeroed(void)
+{
+ return static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON,
+ &init_on_alloc);
+}
+
enum {
/* mark page accessed */
FOLL_TOUCH = 1 << 16,
diff --git a/mm/memory.c b/mm/memory.c
index c67359ddb61a..88252f0e06d0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4719,7 +4719,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
goto next;
}
folio_throttle_swaprate(folio, gfp);
- folio_zero_user(folio, vmf->address);
+ if (!alloc_zeroed())
+ folio_zero_user(folio, vmf->address);
return folio;
}
next:
--
2.45.2
Am 11.10.24 um 17:03 schrieb Zi Yan:
> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
> init_on_free=1 boot options") forces allocated page to be zeroed in
> post_alloc_hook() when init_on_alloc=1.
>
> For order-0 folios, if arch does not define
> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
> the page return from the buddy allocator. So the page is zeroed twice.
> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
> define their own vma_alloc_zeroed_movable_folio().
>
> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
> zero the folio again. Fix it by calling folio_zero_user() only if
> init_on_alloc is set. All arch are impacted.
>
> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> include/linux/highmem.h | 8 +-------
> mm/huge_memory.c | 3 ++-
> mm/internal.h | 6 ++++++
> mm/memory.c | 3 ++-
> 4 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index bec9bd715acf..6e452bd8e7e3 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -224,13 +224,7 @@ static inline
> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
> unsigned long vaddr)
> {
> - struct folio *folio;
> -
> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
> - if (folio)
> - clear_user_highpage(&folio->page, vaddr);
> -
> - return folio;
> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
> }
> #endif
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 82f464865570..5dcbea96edb7 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
> }
> folio_throttle_swaprate(folio, gfp);
>
> - folio_zero_user(folio, addr);
> + if (!alloc_zeroed())
> + folio_zero_user(folio, addr);
It might be reasonable to spell out why we are not using GFP_ZERO somewhere,
something like
/*
* We are not using __GFP_ZERO because folio_zero_user() will make sure that the
* page corresponding to the faulting address will be hot in the cache.
*/
Sth. like that maybe.
Acked-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
On 21 Oct 2024, at 8:23, David Hildenbrand wrote:
> Am 11.10.24 um 17:03 schrieb Zi Yan:
>> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
>> init_on_free=1 boot options") forces allocated page to be zeroed in
>> post_alloc_hook() when init_on_alloc=1.
>>
>> For order-0 folios, if arch does not define
>> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
>> the page return from the buddy allocator. So the page is zeroed twice.
>> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
>> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
>> define their own vma_alloc_zeroed_movable_folio().
>>
>> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
>> zero the folio again. Fix it by calling folio_zero_user() only if
>> init_on_alloc is set. All arch are impacted.
>>
>> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>> include/linux/highmem.h | 8 +-------
>> mm/huge_memory.c | 3 ++-
>> mm/internal.h | 6 ++++++
>> mm/memory.c | 3 ++-
>> 4 files changed, 11 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
>> index bec9bd715acf..6e452bd8e7e3 100644
>> --- a/include/linux/highmem.h
>> +++ b/include/linux/highmem.h
>> @@ -224,13 +224,7 @@ static inline
>> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
>> unsigned long vaddr)
>> {
>> - struct folio *folio;
>> -
>> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
>> - if (folio)
>> - clear_user_highpage(&folio->page, vaddr);
>> -
>> - return folio;
>> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
>> }
>> #endif
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 82f464865570..5dcbea96edb7 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
>> }
>> folio_throttle_swaprate(folio, gfp);
>> - folio_zero_user(folio, addr);
>> + if (!alloc_zeroed())
>> + folio_zero_user(folio, addr);
>
>
>
> It might be reasonable to spell out why we are not using GFP_ZERO somewhere, something like
>
> /*
> * We are not using __GFP_ZERO because folio_zero_user() will make sure that the
> * page corresponding to the faulting address will be hot in the cache.
> */
>
> Sth. like that maybe.
I changed the wording a bit to fit the if statement and put the comment in both
call sites. Let me know how it looks. Thanks.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 830d6aa5bf97..b304bb3ffcef 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1180,6 +1180,11 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
}
folio_throttle_swaprate(folio, gfp);
+ /*
+ * When a folio is not zeroed during allocation (__GFP_ZERO not used),
+ * folio_zero_user() is used to make sure that the page corresponding
+ * to the faulting address will be hot in the cache after zeroing.
+ */
if (!alloc_zeroed())
folio_zero_user(folio, addr);
/*
diff --git a/mm/memory.c b/mm/memory.c
index 0f614523b9f4..42c8bb5fcd8e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4719,6 +4719,13 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
goto next;
}
folio_throttle_swaprate(folio, gfp);
+ /*
+ * When a folio is not zeroed during allocation
+ * (__GFP_ZERO not used), folio_zero_user() is used
+ * to make sure that the page corresponding to the
+ * faulting address will be hot in the cache after
+ * zeroing.
+ */
if (!alloc_zeroed())
folio_zero_user(folio, vmf->address);
return folio;
>
> Acked-by: David Hildenbrand <david@redhat.com>
Thanks.
--
Best Regards,
Yan, Zi
On 21 Oct 2024, at 10:21, Zi Yan wrote:
> On 21 Oct 2024, at 8:23, David Hildenbrand wrote:
>
>> Am 11.10.24 um 17:03 schrieb Zi Yan:
>>> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
>>> init_on_free=1 boot options") forces allocated page to be zeroed in
>>> post_alloc_hook() when init_on_alloc=1.
>>>
>>> For order-0 folios, if arch does not define
>>> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
>>> the page return from the buddy allocator. So the page is zeroed twice.
>>> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
>>> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
>>> define their own vma_alloc_zeroed_movable_folio().
>>>
>>> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
>>> zero the folio again. Fix it by calling folio_zero_user() only if
>>> init_on_alloc is set. All arch are impacted.
>>>
>>> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>>>
>>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>>> ---
>>> include/linux/highmem.h | 8 +-------
>>> mm/huge_memory.c | 3 ++-
>>> mm/internal.h | 6 ++++++
>>> mm/memory.c | 3 ++-
>>> 4 files changed, 11 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
>>> index bec9bd715acf..6e452bd8e7e3 100644
>>> --- a/include/linux/highmem.h
>>> +++ b/include/linux/highmem.h
>>> @@ -224,13 +224,7 @@ static inline
>>> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
>>> unsigned long vaddr)
>>> {
>>> - struct folio *folio;
>>> -
>>> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
>>> - if (folio)
>>> - clear_user_highpage(&folio->page, vaddr);
>>> -
>>> - return folio;
>>> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
>>> }
>>> #endif
>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>> index 82f464865570..5dcbea96edb7 100644
>>> --- a/mm/huge_memory.c
>>> +++ b/mm/huge_memory.c
>>> @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
>>> }
>>> folio_throttle_swaprate(folio, gfp);
>>> - folio_zero_user(folio, addr);
>>> + if (!alloc_zeroed())
>>> + folio_zero_user(folio, addr);
>>
>>
>>
>> It might be reasonable to spell out why we are not using GFP_ZERO somewhere, something like
>>
>> /*
>> * We are not using __GFP_ZERO because folio_zero_user() will make sure that the
>> * page corresponding to the faulting address will be hot in the cache.
>> */
>>
>> Sth. like that maybe.
>
> I changed the wording a bit to fit the if statement and put the comment in both
> call sites. Let me know how it looks. Thanks.
Hi Andrew,
Do you mind folding the changes below into the original patch?
Thanks.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 830d6aa5bf97..b304bb3ffcef 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1180,6 +1180,11 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
}
folio_throttle_swaprate(folio, gfp);
+ /*
+ * When a folio is not zeroed during allocation (__GFP_ZERO not used),
+ * folio_zero_user() is used to make sure that the page corresponding
+ * to the faulting address will be hot in the cache after zeroing.
+ */
if (!alloc_zeroed())
folio_zero_user(folio, addr);
/*
diff --git a/mm/memory.c b/mm/memory.c
index 0f614523b9f4..42c8bb5fcd8e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4719,6 +4719,13 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
goto next;
}
folio_throttle_swaprate(folio, gfp);
+ /*
+ * When a folio is not zeroed during allocation
+ * (__GFP_ZERO not used), folio_zero_user() is used
+ * to make sure that the page corresponding to the
+ * faulting address will be hot in the cache after
+ * zeroing.
+ */
if (!alloc_zeroed())
folio_zero_user(folio, vmf->address);
return folio;
>>
>> Acked-by: David Hildenbrand <david@redhat.com>
>
> Thanks.
--
Best Regards,
Yan, Zi
On 10/11/24 17:03, Zi Yan wrote:
> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
> init_on_free=1 boot options") forces allocated page to be zeroed in
> post_alloc_hook() when init_on_alloc=1.
>
> For order-0 folios, if arch does not define
> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
> the page return from the buddy allocator. So the page is zeroed twice.
> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
> define their own vma_alloc_zeroed_movable_folio().
>
> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
> zero the folio again. Fix it by calling folio_zero_user() only if
> init_on_alloc is set. All arch are impacted.
^ not set?
>
> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> include/linux/highmem.h | 8 +-------
> mm/huge_memory.c | 3 ++-
> mm/internal.h | 6 ++++++
> mm/memory.c | 3 ++-
> 4 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index bec9bd715acf..6e452bd8e7e3 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -224,13 +224,7 @@ static inline
> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
> unsigned long vaddr)
> {
> - struct folio *folio;
> -
> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
> - if (folio)
> - clear_user_highpage(&folio->page, vaddr);
> -
> - return folio;
> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
> }
> #endif
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 82f464865570..5dcbea96edb7 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
> }
> folio_throttle_swaprate(folio, gfp);
>
> - folio_zero_user(folio, addr);
> + if (!alloc_zeroed())
> + folio_zero_user(folio, addr);
> /*
> * The memory barrier inside __folio_mark_uptodate makes sure that
> * folio_zero_user writes become visible before the set_pmd_at()
> diff --git a/mm/internal.h b/mm/internal.h
> index 906da6280c2d..508f7802dd2b 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1233,6 +1233,12 @@ void touch_pud(struct vm_area_struct *vma, unsigned long addr,
> void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
> pmd_t *pmd, bool write);
>
> +static inline bool alloc_zeroed(void)
> +{
> + return static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON,
> + &init_on_alloc);
> +}
> +
> enum {
> /* mark page accessed */
> FOLL_TOUCH = 1 << 16,
> diff --git a/mm/memory.c b/mm/memory.c
> index c67359ddb61a..88252f0e06d0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4719,7 +4719,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
> goto next;
> }
> folio_throttle_swaprate(folio, gfp);
> - folio_zero_user(folio, vmf->address);
> + if (!alloc_zeroed())
> + folio_zero_user(folio, vmf->address);
> return folio;
> }
> next:
On 16 Oct 2024, at 8:53, Vlastimil Babka wrote:
> On 10/11/24 17:03, Zi Yan wrote:
>> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
>> init_on_free=1 boot options") forces allocated page to be zeroed in
>> post_alloc_hook() when init_on_alloc=1.
>>
>> For order-0 folios, if arch does not define
>> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
>> the page return from the buddy allocator. So the page is zeroed twice.
>> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
>> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
>> define their own vma_alloc_zeroed_movable_folio().
>>
>> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
>> zero the folio again. Fix it by calling folio_zero_user() only if
>> init_on_alloc is set. All arch are impacted.
>
> ^ not set?
You are right. The sentence should be:
"Fix it by calling folio_zero_user() only if init_on_alloc is not set."
Hi Andrew,
Do you want me to resend this with fixed commit log?
>
>>
>> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
Thanks.
--
Best Regards,
Yan, Zi
+Vlastimil
On 11 Oct 2024, at 11:03, Zi Yan wrote:
> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
> init_on_free=1 boot options") forces allocated page to be zeroed in
> post_alloc_hook() when init_on_alloc=1.
>
> For order-0 folios, if arch does not define
> vma_alloc_zeroed_movable_folio(), the default implementation again zeros
> the page return from the buddy allocator. So the page is zeroed twice.
> Fix it by passing __GFP_ZERO instead to avoid double page zeroing.
> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they
> define their own vma_alloc_zeroed_movable_folio().
>
> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to
> zero the folio again. Fix it by calling folio_zero_user() only if
> init_on_alloc is set. All arch are impacted.
>
> Added alloc_zeroed() helper to encapsulate the init_on_alloc check.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> include/linux/highmem.h | 8 +-------
> mm/huge_memory.c | 3 ++-
> mm/internal.h | 6 ++++++
> mm/memory.c | 3 ++-
> 4 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index bec9bd715acf..6e452bd8e7e3 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -224,13 +224,7 @@ static inline
> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
> unsigned long vaddr)
> {
> - struct folio *folio;
> -
> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
> - if (folio)
> - clear_user_highpage(&folio->page, vaddr);
> -
> - return folio;
> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
> }
> #endif
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 82f464865570..5dcbea96edb7 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma,
> }
> folio_throttle_swaprate(folio, gfp);
>
> - folio_zero_user(folio, addr);
> + if (!alloc_zeroed())
> + folio_zero_user(folio, addr);
> /*
> * The memory barrier inside __folio_mark_uptodate makes sure that
> * folio_zero_user writes become visible before the set_pmd_at()
> diff --git a/mm/internal.h b/mm/internal.h
> index 906da6280c2d..508f7802dd2b 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1233,6 +1233,12 @@ void touch_pud(struct vm_area_struct *vma, unsigned long addr,
> void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
> pmd_t *pmd, bool write);
>
> +static inline bool alloc_zeroed(void)
> +{
> + return static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON,
> + &init_on_alloc);
> +}
> +
> enum {
> /* mark page accessed */
> FOLL_TOUCH = 1 << 16,
> diff --git a/mm/memory.c b/mm/memory.c
> index c67359ddb61a..88252f0e06d0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4719,7 +4719,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
> goto next;
> }
> folio_throttle_swaprate(folio, gfp);
> - folio_zero_user(folio, vmf->address);
> + if (!alloc_zeroed())
> + folio_zero_user(folio, vmf->address);
> return folio;
> }
> next:
> --
> 2.45.2
Best Regards,
Yan, Zi
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