Signed-off-by: Jike Song <[email protected]>
---
arch/x86/mm/pti.c | 28 ++++------------------------
1 file changed, 4 insertions(+), 24 deletions(-)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 43d4a4a29037..dc611d039bd5 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -164,12 +164,7 @@ static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address)
if (!new_p4d_page)
return NULL;
- if (pgd_none(*pgd)) {
- set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page)));
- new_p4d_page = 0;
- }
- if (new_p4d_page)
- free_page(new_p4d_page);
+ set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page)));
}
BUILD_BUG_ON(pgd_large(*pgd) != 0);
@@ -194,12 +189,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
if (!new_pud_page)
return NULL;
- if (p4d_none(*p4d)) {
- set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page)));
- new_pud_page = 0;
- }
- if (new_pud_page)
- free_page(new_pud_page);
+ set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page)));
}
pud = pud_offset(p4d, address);
@@ -213,12 +203,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address)
if (!new_pmd_page)
return NULL;
- if (pud_none(*pud)) {
- set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page)));
- new_pmd_page = 0;
- }
- if (new_pmd_page)
- free_page(new_pmd_page);
+ set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page)));
}
return pmd_offset(pud, address);
@@ -251,12 +236,7 @@ static __init pte_t *pti_user_pagetable_walk_pte(unsigned long address)
if (!new_pte_page)
return NULL;
- if (pmd_none(*pmd)) {
- set_pmd(pmd, __pmd(_KERNPG_TABLE | __pa(new_pte_page)));
- new_pte_page = 0;
- }
- if (new_pte_page)
- free_page(new_pte_page);
+ set_pmd(pmd, __pmd(_KERNPG_TABLE | __pa(new_pte_page)));
}
pte = pte_offset_kernel(pmd, address);
--
2.14.3
On Sun, 7 Jan 2018, Jike Song wrote:
Care to explain why you think this is not needed?
Thanks,
tglx
On Sun, Jan 07, 2018 at 01:50:59AM +0800, Jike Song wrote:
> Signed-off-by: Jike Song <[email protected]>
It would be nice to have a commit message, particularly in this quite
sensitive series...
Willy
On Sun, Jan 7, 2018 at 3:33 AM, Thomas Gleixner <[email protected]> wrote:
> On Sun, 7 Jan 2018, Jike Song wrote:
>
> Care to explain why you think this is not needed?
>
Hi Thomas,
Look at one of the original code snippets:
162 if (pgd_none(*pgd)) {
163 unsigned long new_p4d_page = __get_free_page(gfp);
164 if (!new_p4d_page)
165 return NULL;
166
167 if (pgd_none(*pgd)) {
168 set_pgd(pgd, __pgd(_KERNPG_TABLE |
__pa(new_p4d_page)));
169 new_p4d_page = 0;
170 }
171 if (new_p4d_page)
172 free_page(new_p4d_page);
173 }
Correct me if I'm too dumb to see the rationale here, but to me there
can't be any difference between
two pgd_none(*pgd) of L162 and L167, so it is always false in L171.
> Thanks,
>
> tglx
--
Thanks,
Jike
On Sun, Jan 7, 2018 at 4:03 AM, Willy Tarreau <[email protected]> wrote:
> On Sun, Jan 07, 2018 at 01:50:59AM +0800, Jike Song wrote:
>> Signed-off-by: Jike Song <[email protected]>
>
> It would be nice to have a commit message, particularly in this quite
> sensitive series...
Yes that's useful, will add it in v2 :)
>
> Willy
--
Thanks,
Jike
On Sun, 7 Jan 2018, Jike Song wrote:
> On Sun, Jan 7, 2018 at 3:33 AM, Thomas Gleixner <[email protected]> wrote:
> > On Sun, 7 Jan 2018, Jike Song wrote:
> >
> > Care to explain why you think this is not needed?
> >
>
> Hi Thomas,
>
> Look at one of the original code snippets:
>
> 162 if (pgd_none(*pgd)) {
> 163 unsigned long new_p4d_page = __get_free_page(gfp);
> 164 if (!new_p4d_page)
> 165 return NULL;
> 166
> 167 if (pgd_none(*pgd)) {
> 168 set_pgd(pgd, __pgd(_KERNPG_TABLE |
> __pa(new_p4d_page)));
> 169 new_p4d_page = 0;
> 170 }
> 171 if (new_p4d_page)
> 172 free_page(new_p4d_page);
> 173 }
>
> Correct me if I'm too dumb to see the rationale here, but to me there
> can't be any difference between
> two pgd_none(*pgd) of L162 and L167, so it is always false in L171.
Right, but this kind of explanation wants to be in the changelog. Empty
changelogs for this kind of change are just not acceptable.
Thanks,
tglx
On Sun, Jan 7, 2018 at 5:48 PM, Thomas Gleixner <[email protected]> wrote:
> On Sun, 7 Jan 2018, Jike Song wrote:
>> On Sun, Jan 7, 2018 at 3:33 AM, Thomas Gleixner <[email protected]> wrote:
>> > On Sun, 7 Jan 2018, Jike Song wrote:
>> >
>> > Care to explain why you think this is not needed?
>> >
>>
>> Hi Thomas,
>>
>> Look at one of the original code snippets:
>>
>> 162 if (pgd_none(*pgd)) {
>> 163 unsigned long new_p4d_page = __get_free_page(gfp);
>> 164 if (!new_p4d_page)
>> 165 return NULL;
>> 166
>> 167 if (pgd_none(*pgd)) {
>> 168 set_pgd(pgd, __pgd(_KERNPG_TABLE |
>> __pa(new_p4d_page)));
>> 169 new_p4d_page = 0;
>> 170 }
>> 171 if (new_p4d_page)
>> 172 free_page(new_p4d_page);
>> 173 }
>>
>> Correct me if I'm too dumb to see the rationale here, but to me there
>> can't be any difference between
>> two pgd_none(*pgd) of L162 and L167, so it is always false in L171.
>
> Right, but this kind of explanation wants to be in the changelog. Empty
> changelogs for this kind of change are just not acceptable.
>
Roger that, just sent v2 out :)
I'm not quite sure but I CCed [email protected] anyway.
> Thanks,
>
> tglx
--
Thanks,
Jike