* [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 4:23 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 4:23 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, zijun_hu, tj, mingo, rientjes,
iamjoonsoo.kim, mgorman
From: zijun_hu <zijun_hu@htc.com>
correct a few logic error for __insert_vmap_area() since the else
if condition is always true and meaningless
in order to fix this issue, if vmap_area inserted is lower than one
on rbtree then walk around left branch; if higher then right branch
otherwise intersects with the other then BUG_ON() is triggered
Signed-off-by: zijun_hu <zijun_hu@htc.com>
---
mm/vmalloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..cc6ecd6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -321,10 +321,10 @@ static void __insert_vmap_area(struct vmap_area *va)
parent = *p;
tmp_va = rb_entry(parent, struct vmap_area, rb_node);
- if (va->va_start < tmp_va->va_end)
- p = &(*p)->rb_left;
- else if (va->va_end > tmp_va->va_start)
- p = &(*p)->rb_right;
+ if (va->va_end <= tmp_va->va_start)
+ p = &parent->rb_left;
+ else if (va->va_start >= tmp_va->va_end)
+ p = &parent->rb_right;
else
BUG();
}
--
1.9.1
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 4:23 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 4:23 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, zijun_hu, tj, mingo, rientjes,
iamjoonsoo.kim, mgorman
From: zijun_hu <zijun_hu@htc.com>
correct a few logic error for __insert_vmap_area() since the else
if condition is always true and meaningless
in order to fix this issue, if vmap_area inserted is lower than one
on rbtree then walk around left branch; if higher then right branch
otherwise intersects with the other then BUG_ON() is triggered
Signed-off-by: zijun_hu <zijun_hu@htc.com>
---
mm/vmalloc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..cc6ecd6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -321,10 +321,10 @@ static void __insert_vmap_area(struct vmap_area *va)
parent = *p;
tmp_va = rb_entry(parent, struct vmap_area, rb_node);
- if (va->va_start < tmp_va->va_end)
- p = &(*p)->rb_left;
- else if (va->va_end > tmp_va->va_start)
- p = &(*p)->rb_right;
+ if (va->va_end <= tmp_va->va_start)
+ p = &parent->rb_left;
+ else if (va->va_start >= tmp_va->va_end)
+ p = &parent->rb_right;
else
BUG();
}
--
1.9.1
--
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^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 4:23 ` zijun_hu
@ 2016-09-21 21:10 ` David Rientjes
-1 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 21:10 UTC (permalink / raw)
To: zijun_hu
Cc: Andrew Morton, linux-mm, linux-kernel, zijun_hu, tj, mingo,
iamjoonsoo.kim, mgorman
On Wed, 21 Sep 2016, zijun_hu wrote:
> From: zijun_hu <zijun_hu@htc.com>
>
> correct a few logic error for __insert_vmap_area() since the else
> if condition is always true and meaningless
>
> in order to fix this issue, if vmap_area inserted is lower than one
> on rbtree then walk around left branch; if higher then right branch
> otherwise intersects with the other then BUG_ON() is triggered
>
Under normal operation, you're right that the "else if" conditional should
always succeed: we don't want to BUG() unless there's a bug. The original
code can catch instances when va->va_start == tmp_va->va_end where we
should BUG(). Your code silently ignores it.
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 21:10 ` David Rientjes
0 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 21:10 UTC (permalink / raw)
To: zijun_hu
Cc: Andrew Morton, linux-mm, linux-kernel, zijun_hu, tj, mingo,
iamjoonsoo.kim, mgorman
On Wed, 21 Sep 2016, zijun_hu wrote:
> From: zijun_hu <zijun_hu@htc.com>
>
> correct a few logic error for __insert_vmap_area() since the else
> if condition is always true and meaningless
>
> in order to fix this issue, if vmap_area inserted is lower than one
> on rbtree then walk around left branch; if higher then right branch
> otherwise intersects with the other then BUG_ON() is triggered
>
Under normal operation, you're right that the "else if" conditional should
always succeed: we don't want to BUG() unless there's a bug. The original
code can catch instances when va->va_start == tmp_va->va_end where we
should BUG(). Your code silently ignores it.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 21:10 ` David Rientjes
@ 2016-09-21 22:35 ` zijun_hu
-1 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 22:35 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 5:10, David Rientjes wrote:
> On Wed, 21 Sep 2016, zijun_hu wrote:
>
>> From: zijun_hu <zijun_hu@htc.com>
>>
>> correct a few logic error for __insert_vmap_area() since the else
>> if condition is always true and meaningless
>>
>> in order to fix this issue, if vmap_area inserted is lower than one
>> on rbtree then walk around left branch; if higher then right branch
>> otherwise intersects with the other then BUG_ON() is triggered
>>
>
> Under normal operation, you're right that the "else if" conditional should
> always succeed: we don't want to BUG() unless there's a bug. The original
> code can catch instances when va->va_start == tmp_va->va_end where we
> should BUG(). Your code silently ignores it.
>
Hmm, the BUG_ON() appears in the original code, i don't introduce it.
it maybe be better to consider va->va_start == tmp_va->va_end as normal case
and should not BUG_ON() it since the available range of vmap_erea include
the start boundary but the end, BTW, represented as [start, end)
this patch correct the logic to that mentioned in the comments, it maybe be
more logical and more understandable
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 22:35 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 22:35 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 5:10, David Rientjes wrote:
> On Wed, 21 Sep 2016, zijun_hu wrote:
>
>> From: zijun_hu <zijun_hu@htc.com>
>>
>> correct a few logic error for __insert_vmap_area() since the else
>> if condition is always true and meaningless
>>
>> in order to fix this issue, if vmap_area inserted is lower than one
>> on rbtree then walk around left branch; if higher then right branch
>> otherwise intersects with the other then BUG_ON() is triggered
>>
>
> Under normal operation, you're right that the "else if" conditional should
> always succeed: we don't want to BUG() unless there's a bug. The original
> code can catch instances when va->va_start == tmp_va->va_end where we
> should BUG(). Your code silently ignores it.
>
Hmm, the BUG_ON() appears in the original code, i don't introduce it.
it maybe be better to consider va->va_start == tmp_va->va_end as normal case
and should not BUG_ON() it since the available range of vmap_erea include
the start boundary but the end, BTW, represented as [start, end)
this patch correct the logic to that mentioned in the comments, it maybe be
more logical and more understandable
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 22:35 ` zijun_hu
@ 2016-09-21 22:45 ` David Rientjes
-1 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 22:45 UTC (permalink / raw)
To: zijun_hu
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On Thu, 22 Sep 2016, zijun_hu wrote:
> >> correct a few logic error for __insert_vmap_area() since the else
> >> if condition is always true and meaningless
> >>
> >> in order to fix this issue, if vmap_area inserted is lower than one
> >> on rbtree then walk around left branch; if higher then right branch
> >> otherwise intersects with the other then BUG_ON() is triggered
> >>
> >
> > Under normal operation, you're right that the "else if" conditional should
> > always succeed: we don't want to BUG() unless there's a bug. The original
> > code can catch instances when va->va_start == tmp_va->va_end where we
> > should BUG(). Your code silently ignores it.
> >
> Hmm, the BUG_ON() appears in the original code, i don't introduce it.
> it maybe be better to consider va->va_start == tmp_va->va_end as normal case
> and should not BUG_ON() it since the available range of vmap_erea include
> the start boundary but the end, BTW, represented as [start, end)
>
We don't support inserting when va->va_start == tmp_va->va_end, plain and
simple. There's no reason to do so. NACK to the patch.
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 22:45 ` David Rientjes
0 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 22:45 UTC (permalink / raw)
To: zijun_hu
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On Thu, 22 Sep 2016, zijun_hu wrote:
> >> correct a few logic error for __insert_vmap_area() since the else
> >> if condition is always true and meaningless
> >>
> >> in order to fix this issue, if vmap_area inserted is lower than one
> >> on rbtree then walk around left branch; if higher then right branch
> >> otherwise intersects with the other then BUG_ON() is triggered
> >>
> >
> > Under normal operation, you're right that the "else if" conditional should
> > always succeed: we don't want to BUG() unless there's a bug. The original
> > code can catch instances when va->va_start == tmp_va->va_end where we
> > should BUG(). Your code silently ignores it.
> >
> Hmm, the BUG_ON() appears in the original code, i don't introduce it.
> it maybe be better to consider va->va_start == tmp_va->va_end as normal case
> and should not BUG_ON() it since the available range of vmap_erea include
> the start boundary but the end, BTW, represented as [start, end)
>
We don't support inserting when va->va_start == tmp_va->va_end, plain and
simple. There's no reason to do so. NACK to the patch.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 22:45 ` David Rientjes
@ 2016-09-21 23:10 ` zijun_hu
-1 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 23:10 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 6:45, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>>> correct a few logic error for __insert_vmap_area() since the else
>>>> if condition is always true and meaningless
>>>>
>>>> in order to fix this issue, if vmap_area inserted is lower than one
>>>> on rbtree then walk around left branch; if higher then right branch
>>>> otherwise intersects with the other then BUG_ON() is triggered
>>>>
>>>
>>> Under normal operation, you're right that the "else if" conditional should
>>> always succeed: we don't want to BUG() unless there's a bug. The original
>>> code can catch instances when va->va_start == tmp_va->va_end where we
>>> should BUG(). Your code silently ignores it.
>>>
>> Hmm, the BUG_ON() appears in the original code, i don't introduce it.
>> it maybe be better to consider va->va_start == tmp_va->va_end as normal case
>> and should not BUG_ON() it since the available range of vmap_erea include
>> the start boundary but the end, BTW, represented as [start, end)
>>
>
> We don't support inserting when va->va_start == tmp_va->va_end, plain and
> simple. There's no reason to do so. NACK to the patch.
>
i am sorry i disagree with you because
1) in almost all context of vmalloc, original logic treat the special case as normal
for example, __find_vmap_area() or alloc_vmap_area()
2) don't use the limited vmap area effectively, it maybe causes BUG_ON() easy
3) consider below case
it provided there have been two vmap_areas [4, 12) and [20, 28), what will happens
when alloc_vmap_area(8, 4, 6, 24,...)? should we use [12,20) for our request?
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 23:10 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 23:10 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 6:45, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>>> correct a few logic error for __insert_vmap_area() since the else
>>>> if condition is always true and meaningless
>>>>
>>>> in order to fix this issue, if vmap_area inserted is lower than one
>>>> on rbtree then walk around left branch; if higher then right branch
>>>> otherwise intersects with the other then BUG_ON() is triggered
>>>>
>>>
>>> Under normal operation, you're right that the "else if" conditional should
>>> always succeed: we don't want to BUG() unless there's a bug. The original
>>> code can catch instances when va->va_start == tmp_va->va_end where we
>>> should BUG(). Your code silently ignores it.
>>>
>> Hmm, the BUG_ON() appears in the original code, i don't introduce it.
>> it maybe be better to consider va->va_start == tmp_va->va_end as normal case
>> and should not BUG_ON() it since the available range of vmap_erea include
>> the start boundary but the end, BTW, represented as [start, end)
>>
>
> We don't support inserting when va->va_start == tmp_va->va_end, plain and
> simple. There's no reason to do so. NACK to the patch.
>
i am sorry i disagree with you because
1) in almost all context of vmalloc, original logic treat the special case as normal
for example, __find_vmap_area() or alloc_vmap_area()
2) don't use the limited vmap area effectively, it maybe causes BUG_ON() easy
3) consider below case
it provided there have been two vmap_areas [4, 12) and [20, 28), what will happens
when alloc_vmap_area(8, 4, 6, 24,...)? should we use [12,20) for our request?
--
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 23:10 ` zijun_hu
@ 2016-09-21 23:15 ` David Rientjes
-1 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 23:15 UTC (permalink / raw)
To: zijun_hu
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On Thu, 22 Sep 2016, zijun_hu wrote:
> > We don't support inserting when va->va_start == tmp_va->va_end, plain and
> > simple. There's no reason to do so. NACK to the patch.
> >
> i am sorry i disagree with you because
> 1) in almost all context of vmalloc, original logic treat the special case as normal
> for example, __find_vmap_area() or alloc_vmap_area()
The ranges are [start, end) like everywhere else. __find_vmap_area() is
implemented as such for the passed address. The address is aligned in
alloc_vmap_area(), there's no surprise here. The logic is correct in
__insert_vmap_area().
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 23:15 ` David Rientjes
0 siblings, 0 replies; 18+ messages in thread
From: David Rientjes @ 2016-09-21 23:15 UTC (permalink / raw)
To: zijun_hu
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On Thu, 22 Sep 2016, zijun_hu wrote:
> > We don't support inserting when va->va_start == tmp_va->va_end, plain and
> > simple. There's no reason to do so. NACK to the patch.
> >
> i am sorry i disagree with you because
> 1) in almost all context of vmalloc, original logic treat the special case as normal
> for example, __find_vmap_area() or alloc_vmap_area()
The ranges are [start, end) like everywhere else. __find_vmap_area() is
implemented as such for the passed address. The address is aligned in
alloc_vmap_area(), there's no surprise here. The logic is correct in
__insert_vmap_area().
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 23:15 ` David Rientjes
@ 2016-09-21 23:55 ` zijun_hu
-1 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 23:55 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 7:15, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>> We don't support inserting when va->va_start == tmp_va->va_end, plain and
>>> simple. There's no reason to do so. NACK to the patch.
>>>
>> i am sorry i disagree with you because
>> 1) in almost all context of vmalloc, original logic treat the special case as normal
>> for example, __find_vmap_area() or alloc_vmap_area()
>
> The ranges are [start, end) like everywhere else. __find_vmap_area() is
> implemented as such for the passed address. The address is aligned in
> alloc_vmap_area(), there's no surprise here. The logic is correct in
> __insert_vmap_area().
>
1) is the desire behavior of __insert_vmap_area() conform with that mentioned
in my comments?
2) which way of code implementation can present the desire purpose more clear
and more understandable?
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-21 23:55 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-21 23:55 UTC (permalink / raw)
To: David Rientjes
Cc: zijun_hu, Andrew Morton, linux-mm, linux-kernel, tj, mingo,
iamjoonsoo.kim, mgorman
On 2016/9/22 7:15, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>> We don't support inserting when va->va_start == tmp_va->va_end, plain and
>>> simple. There's no reason to do so. NACK to the patch.
>>>
>> i am sorry i disagree with you because
>> 1) in almost all context of vmalloc, original logic treat the special case as normal
>> for example, __find_vmap_area() or alloc_vmap_area()
>
> The ranges are [start, end) like everywhere else. __find_vmap_area() is
> implemented as such for the passed address. The address is aligned in
> alloc_vmap_area(), there's no surprise here. The logic is correct in
> __insert_vmap_area().
>
1) is the desire behavior of __insert_vmap_area() conform with that mentioned
in my comments?
2) which way of code implementation can present the desire purpose more clear
and more understandable?
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [RFC PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 4:23 ` zijun_hu
@ 2016-09-22 1:36 ` zijun_hu
-1 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-22 1:36 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, zijun_hu, tj, mingo, rientjes,
iamjoonsoo.kim, mgorman
On 09/21/2016 12:23 PM, zijun_hu wrote:
> From: zijun_hu <zijun_hu@htc.com>
>
> correct a few logic error for __insert_vmap_area() since the else
> if condition is always true and meaningless
>
> in order to fix this issue, if vmap_area inserted is lower than one
> on rbtree then walk around left branch; if higher then right branch
> otherwise intersects with the other then BUG_ON() is triggered
>
> Signed-off-by: zijun_hu <zijun_hu@htc.com>
i give more explanation to the intent of my change
any comments is welcome
> ---
> mm/vmalloc.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 91f44e7..cc6ecd6 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -321,10 +321,10 @@ static void __insert_vmap_area(struct vmap_area *va)
>
> parent = *p;
> tmp_va = rb_entry(parent, struct vmap_area, rb_node);
> - if (va->va_start < tmp_va->va_end)
> - p = &(*p)->rb_left;
> - else if (va->va_end > tmp_va->va_start)
> - p = &(*p)->rb_right;
this else if condition is always true and meaningless as long as there are no
zero sized vamp_area due to the following expression
va->va_end > va->va_start >= tmp_va->va_end > tmp_va->va_start
> + if (va->va_end <= tmp_va->va_start)
> + p = &parent->rb_left;
if the vamp_area to be inserted is lower than that on the rbtree then
we walk around the left branch of the node given
consider va->va_end == tmp_va->va_start as legal case which represent
two neighbor areas tightly
BTW, the available range of a vmap area include the start boundary not the
end, namely, [start, end)
> + else if (va->va_start >= tmp_va->va_end)
> + p = &parent->rb_right;
if the vamp_area to be inserted is higher than that on the rbtree then
we walk around the right branch of the node given
> else
> BUG();
this indicate the vamp_area to be inserted have intersects with that on the rbtree
then we remain the BUG() logic
> }
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [RFC PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-22 1:36 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-22 1:36 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, linux-kernel, zijun_hu, tj, mingo, rientjes,
iamjoonsoo.kim, mgorman
On 09/21/2016 12:23 PM, zijun_hu wrote:
> From: zijun_hu <zijun_hu@htc.com>
>
> correct a few logic error for __insert_vmap_area() since the else
> if condition is always true and meaningless
>
> in order to fix this issue, if vmap_area inserted is lower than one
> on rbtree then walk around left branch; if higher then right branch
> otherwise intersects with the other then BUG_ON() is triggered
>
> Signed-off-by: zijun_hu <zijun_hu@htc.com>
i give more explanation to the intent of my change
any comments is welcome
> ---
> mm/vmalloc.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 91f44e7..cc6ecd6 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -321,10 +321,10 @@ static void __insert_vmap_area(struct vmap_area *va)
>
> parent = *p;
> tmp_va = rb_entry(parent, struct vmap_area, rb_node);
> - if (va->va_start < tmp_va->va_end)
> - p = &(*p)->rb_left;
> - else if (va->va_end > tmp_va->va_start)
> - p = &(*p)->rb_right;
this else if condition is always true and meaningless as long as there are no
zero sized vamp_area due to the following expression
va->va_end > va->va_start >= tmp_va->va_end > tmp_va->va_start
> + if (va->va_end <= tmp_va->va_start)
> + p = &parent->rb_left;
if the vamp_area to be inserted is lower than that on the rbtree then
we walk around the left branch of the node given
consider va->va_end == tmp_va->va_start as legal case which represent
two neighbor areas tightly
BTW, the available range of a vmap area include the start boundary not the
end, namely, [start, end)
> + else if (va->va_start >= tmp_va->va_end)
> + p = &parent->rb_right;
if the vamp_area to be inserted is higher than that on the rbtree then
we walk around the right branch of the node given
> else
> BUG();
this indicate the vamp_area to be inserted have intersects with that on the rbtree
then we remain the BUG() logic
> }
>
--
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^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
2016-09-21 23:15 ` David Rientjes
@ 2016-09-27 6:07 ` zijun_hu
-1 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-27 6:07 UTC (permalink / raw)
To: David Rientjes
Cc: linux-mm, linux-kernel, zijun_hu, Andrew Morton, tj, mingo,
iamjoonsoo.kim, mgorman
On 09/22/2016 07:15 AM, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>> We don't support inserting when va->va_start == tmp_va->va_end, plain and
>>> simple. There's no reason to do so. NACK to the patch.
>>>
>> i am sorry i disagree with you because
>> 1) in almost all context of vmalloc, original logic treat the special case as normal
>> for example, __find_vmap_area() or alloc_vmap_area()
>
> The ranges are [start, end) like everywhere else. __find_vmap_area() is
> implemented as such for the passed address. The address is aligned in
> alloc_vmap_area(), there's no surprise here. The logic is correct in
> __insert_vmap_area().
>
i am sorry to disagree with you
i will resend this patch with more detailed illustration
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
@ 2016-09-27 6:07 ` zijun_hu
0 siblings, 0 replies; 18+ messages in thread
From: zijun_hu @ 2016-09-27 6:07 UTC (permalink / raw)
To: David Rientjes
Cc: linux-mm, linux-kernel, zijun_hu, Andrew Morton, tj, mingo,
iamjoonsoo.kim, mgorman
On 09/22/2016 07:15 AM, David Rientjes wrote:
> On Thu, 22 Sep 2016, zijun_hu wrote:
>
>>> We don't support inserting when va->va_start == tmp_va->va_end, plain and
>>> simple. There's no reason to do so. NACK to the patch.
>>>
>> i am sorry i disagree with you because
>> 1) in almost all context of vmalloc, original logic treat the special case as normal
>> for example, __find_vmap_area() or alloc_vmap_area()
>
> The ranges are [start, end) like everywhere else. __find_vmap_area() is
> implemented as such for the passed address. The address is aligned in
> alloc_vmap_area(), there's no surprise here. The logic is correct in
> __insert_vmap_area().
>
i am sorry to disagree with you
i will resend this patch with more detailed illustration
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 18+ messages in thread
end of thread, other threads:[~2016-09-27 6:07 UTC | newest]
Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-21 4:23 [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area() zijun_hu
2016-09-21 4:23 ` zijun_hu
2016-09-21 21:10 ` David Rientjes
2016-09-21 21:10 ` David Rientjes
2016-09-21 22:35 ` zijun_hu
2016-09-21 22:35 ` zijun_hu
2016-09-21 22:45 ` David Rientjes
2016-09-21 22:45 ` David Rientjes
2016-09-21 23:10 ` zijun_hu
2016-09-21 23:10 ` zijun_hu
2016-09-21 23:15 ` David Rientjes
2016-09-21 23:15 ` David Rientjes
2016-09-21 23:55 ` zijun_hu
2016-09-21 23:55 ` zijun_hu
2016-09-27 6:07 ` zijun_hu
2016-09-27 6:07 ` zijun_hu
2016-09-22 1:36 ` [RFC PATCH " zijun_hu
2016-09-22 1:36 ` zijun_hu
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