Let's make sure splitting a resource on memory hotunplug will never fail.
This will become more relevant once we merge selected System RAM
resources - then, we'll trigger that case more often on memory hotunplug.
In general, this function is already unlikely to fail. When we remove
memory, we free up quite a lot of metadata (memmap, page tables, memory
block device, etc.). The only reason it could really fail would be when
injecting allocation errors.
All other error cases inside release_mem_region_adjustable() seem to be
sanity checks if the function would be abused in different context -
let's add WARN_ON_ONCE() in these cases so we can catch them.
Cc: Andrew Morton <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Pankaj Gupta <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
---
include/linux/ioport.h | 4 ++--
kernel/resource.c | 49 ++++++++++++++++++++++++------------------
mm/memory_hotplug.c | 22 +------------------
3 files changed, 31 insertions(+), 44 deletions(-)
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6c2b06fe8beb7..52a91f5fa1a36 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -248,8 +248,8 @@ extern struct resource * __request_region(struct resource *,
extern void __release_region(struct resource *, resource_size_t,
resource_size_t);
#ifdef CONFIG_MEMORY_HOTREMOVE
-extern int release_mem_region_adjustable(struct resource *, resource_size_t,
- resource_size_t);
+extern void release_mem_region_adjustable(struct resource *, resource_size_t,
+ resource_size_t);
#endif
/* Wrappers for managed devices */
diff --git a/kernel/resource.c b/kernel/resource.c
index f1175ce93a1d5..36b3552210120 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1258,21 +1258,28 @@ EXPORT_SYMBOL(__release_region);
* assumes that all children remain in the lower address entry for
* simplicity. Enhance this logic when necessary.
*/
-int release_mem_region_adjustable(struct resource *parent,
- resource_size_t start, resource_size_t size)
+void release_mem_region_adjustable(struct resource *parent,
+ resource_size_t start, resource_size_t size)
{
+ struct resource *new_res = NULL;
+ bool alloc_nofail = false;
struct resource **p;
struct resource *res;
- struct resource *new_res;
resource_size_t end;
- int ret = -EINVAL;
end = start + size - 1;
- if ((start < parent->start) || (end > parent->end))
- return ret;
+ if (WARN_ON_ONCE((start < parent->start) || (end > parent->end)))
+ return;
- /* The alloc_resource() result gets checked later */
- new_res = alloc_resource(GFP_KERNEL);
+ /*
+ * We free up quite a lot of memory on memory hotunplug (esp., memap),
+ * just before releasing the region. This is highly unlikely to
+ * fail - let's play save and make it never fail as the caller cannot
+ * perform any error handling (e.g., trying to re-add memory will fail
+ * similarly).
+ */
+retry:
+ new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
p = &parent->child;
write_lock(&resource_lock);
@@ -1298,7 +1305,6 @@ int release_mem_region_adjustable(struct resource *parent,
* so if we are dealing with them, let us just back off here.
*/
if (!(res->flags & IORESOURCE_SYSRAM)) {
- ret = 0;
break;
}
@@ -1315,20 +1321,23 @@ int release_mem_region_adjustable(struct resource *parent,
/* free the whole entry */
*p = res->sibling;
free_resource(res);
- ret = 0;
} else if (res->start == start && res->end != end) {
/* adjust the start */
- ret = __adjust_resource(res, end + 1,
- res->end - end);
+ WARN_ON_ONCE(__adjust_resource(res, end + 1,
+ res->end - end));
} else if (res->start != start && res->end == end) {
/* adjust the end */
- ret = __adjust_resource(res, res->start,
- start - res->start);
+ WARN_ON_ONCE(__adjust_resource(res, res->start,
+ start - res->start));
} else {
- /* split into two entries */
+ /* split into two entries - we need a new resource */
if (!new_res) {
- ret = -ENOMEM;
- break;
+ new_res = alloc_resource(GFP_ATOMIC);
+ if (!new_res) {
+ alloc_nofail = true;
+ write_unlock(&resource_lock);
+ goto retry;
+ }
}
new_res->name = res->name;
new_res->start = end + 1;
@@ -1339,9 +1348,8 @@ int release_mem_region_adjustable(struct resource *parent,
new_res->sibling = res->sibling;
new_res->child = NULL;
- ret = __adjust_resource(res, res->start,
- start - res->start);
- if (ret)
+ if (WARN_ON_ONCE(__adjust_resource(res, res->start,
+ start - res->start)))
break;
res->sibling = new_res;
new_res = NULL;
@@ -1352,7 +1360,6 @@ int release_mem_region_adjustable(struct resource *parent,
write_unlock(&resource_lock);
free_resource(new_res);
- return ret;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index baded53b9ff92..4c47b68a9f4b5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1724,26 +1724,6 @@ void try_offline_node(int nid)
}
EXPORT_SYMBOL(try_offline_node);
-static void __release_memory_resource(resource_size_t start,
- resource_size_t size)
-{
- int ret;
-
- /*
- * When removing memory in the same granularity as it was added,
- * this function never fails. It might only fail if resources
- * have to be adjusted or split. We'll ignore the error, as
- * removing of memory cannot fail.
- */
- ret = release_mem_region_adjustable(&iomem_resource, start, size);
- if (ret) {
- resource_size_t endres = start + size - 1;
-
- pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
- &start, &endres, ret);
- }
-}
-
static int __ref try_remove_memory(int nid, u64 start, u64 size)
{
int rc = 0;
@@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
memblock_remove(start, size);
}
- __release_memory_resource(start, size);
+ release_mem_region_adjustable(&iomem_resource, start, size);
try_offline_node(nid);
--
2.26.2
On Tue, Sep 08, 2020 at 10:10:06PM +0200, David Hildenbrand wrote:
>Let's make sure splitting a resource on memory hotunplug will never fail.
>This will become more relevant once we merge selected System RAM
>resources - then, we'll trigger that case more often on memory hotunplug.
>
>In general, this function is already unlikely to fail. When we remove
>memory, we free up quite a lot of metadata (memmap, page tables, memory
>block device, etc.). The only reason it could really fail would be when
>injecting allocation errors.
>
>All other error cases inside release_mem_region_adjustable() seem to be
>sanity checks if the function would be abused in different context -
>let's add WARN_ON_ONCE() in these cases so we can catch them.
>
>Cc: Andrew Morton <[email protected]>
>Cc: Michal Hocko <[email protected]>
>Cc: Dan Williams <[email protected]>
>Cc: Jason Gunthorpe <[email protected]>
>Cc: Kees Cook <[email protected]>
>Cc: Ard Biesheuvel <[email protected]>
>Cc: Pankaj Gupta <[email protected]>
>Cc: Baoquan He <[email protected]>
>Cc: Wei Yang <[email protected]>
>Signed-off-by: David Hildenbrand <[email protected]>
>---
> include/linux/ioport.h | 4 ++--
> kernel/resource.c | 49 ++++++++++++++++++++++++------------------
> mm/memory_hotplug.c | 22 +------------------
> 3 files changed, 31 insertions(+), 44 deletions(-)
>
>diff --git a/include/linux/ioport.h b/include/linux/ioport.h
>index 6c2b06fe8beb7..52a91f5fa1a36 100644
>--- a/include/linux/ioport.h
>+++ b/include/linux/ioport.h
>@@ -248,8 +248,8 @@ extern struct resource * __request_region(struct resource *,
> extern void __release_region(struct resource *, resource_size_t,
> resource_size_t);
> #ifdef CONFIG_MEMORY_HOTREMOVE
>-extern int release_mem_region_adjustable(struct resource *, resource_size_t,
>- resource_size_t);
>+extern void release_mem_region_adjustable(struct resource *, resource_size_t,
>+ resource_size_t);
> #endif
>
> /* Wrappers for managed devices */
>diff --git a/kernel/resource.c b/kernel/resource.c
>index f1175ce93a1d5..36b3552210120 100644
>--- a/kernel/resource.c
>+++ b/kernel/resource.c
>@@ -1258,21 +1258,28 @@ EXPORT_SYMBOL(__release_region);
> * assumes that all children remain in the lower address entry for
> * simplicity. Enhance this logic when necessary.
> */
>-int release_mem_region_adjustable(struct resource *parent,
>- resource_size_t start, resource_size_t size)
>+void release_mem_region_adjustable(struct resource *parent,
>+ resource_size_t start, resource_size_t size)
> {
>+ struct resource *new_res = NULL;
>+ bool alloc_nofail = false;
> struct resource **p;
> struct resource *res;
>- struct resource *new_res;
> resource_size_t end;
>- int ret = -EINVAL;
>
> end = start + size - 1;
>- if ((start < parent->start) || (end > parent->end))
>- return ret;
>+ if (WARN_ON_ONCE((start < parent->start) || (end > parent->end)))
>+ return;
>
>- /* The alloc_resource() result gets checked later */
>- new_res = alloc_resource(GFP_KERNEL);
>+ /*
>+ * We free up quite a lot of memory on memory hotunplug (esp., memap),
>+ * just before releasing the region. This is highly unlikely to
>+ * fail - let's play save and make it never fail as the caller cannot
>+ * perform any error handling (e.g., trying to re-add memory will fail
>+ * similarly).
>+ */
>+retry:
>+ new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
>
It looks like a bold change, while I don't find a reason to object it.
> p = &parent->child;
> write_lock(&resource_lock);
>@@ -1298,7 +1305,6 @@ int release_mem_region_adjustable(struct resource *parent,
> * so if we are dealing with them, let us just back off here.
> */
> if (!(res->flags & IORESOURCE_SYSRAM)) {
>- ret = 0;
> break;
> }
>
>@@ -1315,20 +1321,23 @@ int release_mem_region_adjustable(struct resource *parent,
> /* free the whole entry */
> *p = res->sibling;
> free_resource(res);
>- ret = 0;
> } else if (res->start == start && res->end != end) {
> /* adjust the start */
>- ret = __adjust_resource(res, end + 1,
>- res->end - end);
>+ WARN_ON_ONCE(__adjust_resource(res, end + 1,
>+ res->end - end));
> } else if (res->start != start && res->end == end) {
> /* adjust the end */
>- ret = __adjust_resource(res, res->start,
>- start - res->start);
>+ WARN_ON_ONCE(__adjust_resource(res, res->start,
>+ start - res->start));
> } else {
>- /* split into two entries */
>+ /* split into two entries - we need a new resource */
> if (!new_res) {
>- ret = -ENOMEM;
>- break;
>+ new_res = alloc_resource(GFP_ATOMIC);
>+ if (!new_res) {
>+ alloc_nofail = true;
>+ write_unlock(&resource_lock);
>+ goto retry;
>+ }
> }
> new_res->name = res->name;
> new_res->start = end + 1;
>@@ -1339,9 +1348,8 @@ int release_mem_region_adjustable(struct resource *parent,
> new_res->sibling = res->sibling;
> new_res->child = NULL;
>
>- ret = __adjust_resource(res, res->start,
>- start - res->start);
>- if (ret)
>+ if (WARN_ON_ONCE(__adjust_resource(res, res->start,
>+ start - res->start)))
> break;
> res->sibling = new_res;
> new_res = NULL;
>@@ -1352,7 +1360,6 @@ int release_mem_region_adjustable(struct resource *parent,
>
> write_unlock(&resource_lock);
> free_resource(new_res);
>- return ret;
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
>diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>index baded53b9ff92..4c47b68a9f4b5 100644
>--- a/mm/memory_hotplug.c
>+++ b/mm/memory_hotplug.c
>@@ -1724,26 +1724,6 @@ void try_offline_node(int nid)
> }
> EXPORT_SYMBOL(try_offline_node);
>
>-static void __release_memory_resource(resource_size_t start,
>- resource_size_t size)
>-{
>- int ret;
>-
>- /*
>- * When removing memory in the same granularity as it was added,
>- * this function never fails. It might only fail if resources
>- * have to be adjusted or split. We'll ignore the error, as
>- * removing of memory cannot fail.
>- */
>- ret = release_mem_region_adjustable(&iomem_resource, start, size);
>- if (ret) {
>- resource_size_t endres = start + size - 1;
>-
>- pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
>- &start, &endres, ret);
>- }
>-}
>-
> static int __ref try_remove_memory(int nid, u64 start, u64 size)
> {
> int rc = 0;
>@@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
> memblock_remove(start, size);
> }
>
>- __release_memory_resource(start, size);
>+ release_mem_region_adjustable(&iomem_resource, start, size);
>
> try_offline_node(nid);
>
>--
>2.26.2
--
Wei Yang
Help you, Help me
On Tue, Sep 08, 2020 at 10:10:06PM +0200, David Hildenbrand wrote:
>Let's make sure splitting a resource on memory hotunplug will never fail.
>This will become more relevant once we merge selected System RAM
>resources - then, we'll trigger that case more often on memory hotunplug.
>
>In general, this function is already unlikely to fail. When we remove
>memory, we free up quite a lot of metadata (memmap, page tables, memory
>block device, etc.). The only reason it could really fail would be when
>injecting allocation errors.
>
>All other error cases inside release_mem_region_adjustable() seem to be
>sanity checks if the function would be abused in different context -
>let's add WARN_ON_ONCE() in these cases so we can catch them.
>
>Cc: Andrew Morton <[email protected]>
>Cc: Michal Hocko <[email protected]>
>Cc: Dan Williams <[email protected]>
>Cc: Jason Gunthorpe <[email protected]>
>Cc: Kees Cook <[email protected]>
>Cc: Ard Biesheuvel <[email protected]>
>Cc: Pankaj Gupta <[email protected]>
>Cc: Baoquan He <[email protected]>
>Cc: Wei Yang <[email protected]>
>Signed-off-by: David Hildenbrand <[email protected]>
>---
> include/linux/ioport.h | 4 ++--
> kernel/resource.c | 49 ++++++++++++++++++++++++------------------
> mm/memory_hotplug.c | 22 +------------------
> 3 files changed, 31 insertions(+), 44 deletions(-)
>
>diff --git a/include/linux/ioport.h b/include/linux/ioport.h
>index 6c2b06fe8beb7..52a91f5fa1a36 100644
>--- a/include/linux/ioport.h
>+++ b/include/linux/ioport.h
>@@ -248,8 +248,8 @@ extern struct resource * __request_region(struct resource *,
> extern void __release_region(struct resource *, resource_size_t,
> resource_size_t);
> #ifdef CONFIG_MEMORY_HOTREMOVE
>-extern int release_mem_region_adjustable(struct resource *, resource_size_t,
>- resource_size_t);
>+extern void release_mem_region_adjustable(struct resource *, resource_size_t,
>+ resource_size_t);
> #endif
>
> /* Wrappers for managed devices */
>diff --git a/kernel/resource.c b/kernel/resource.c
>index f1175ce93a1d5..36b3552210120 100644
>--- a/kernel/resource.c
>+++ b/kernel/resource.c
>@@ -1258,21 +1258,28 @@ EXPORT_SYMBOL(__release_region);
> * assumes that all children remain in the lower address entry for
> * simplicity. Enhance this logic when necessary.
> */
>-int release_mem_region_adjustable(struct resource *parent,
>- resource_size_t start, resource_size_t size)
>+void release_mem_region_adjustable(struct resource *parent,
>+ resource_size_t start, resource_size_t size)
> {
>+ struct resource *new_res = NULL;
>+ bool alloc_nofail = false;
> struct resource **p;
> struct resource *res;
>- struct resource *new_res;
> resource_size_t end;
>- int ret = -EINVAL;
>
> end = start + size - 1;
>- if ((start < parent->start) || (end > parent->end))
>- return ret;
>+ if (WARN_ON_ONCE((start < parent->start) || (end > parent->end)))
>+ return;
>
>- /* The alloc_resource() result gets checked later */
>- new_res = alloc_resource(GFP_KERNEL);
>+ /*
>+ * We free up quite a lot of memory on memory hotunplug (esp., memap),
>+ * just before releasing the region. This is highly unlikely to
>+ * fail - let's play save and make it never fail as the caller cannot
>+ * perform any error handling (e.g., trying to re-add memory will fail
>+ * similarly).
>+ */
>+retry:
>+ new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
>
> p = &parent->child;
> write_lock(&resource_lock);
>@@ -1298,7 +1305,6 @@ int release_mem_region_adjustable(struct resource *parent,
> * so if we are dealing with them, let us just back off here.
> */
> if (!(res->flags & IORESOURCE_SYSRAM)) {
>- ret = 0;
> break;
> }
>
>@@ -1315,20 +1321,23 @@ int release_mem_region_adjustable(struct resource *parent,
> /* free the whole entry */
> *p = res->sibling;
> free_resource(res);
>- ret = 0;
> } else if (res->start == start && res->end != end) {
> /* adjust the start */
>- ret = __adjust_resource(res, end + 1,
>- res->end - end);
>+ WARN_ON_ONCE(__adjust_resource(res, end + 1,
>+ res->end - end));
> } else if (res->start != start && res->end == end) {
> /* adjust the end */
>- ret = __adjust_resource(res, res->start,
>- start - res->start);
>+ WARN_ON_ONCE(__adjust_resource(res, res->start,
>+ start - res->start));
> } else {
>- /* split into two entries */
>+ /* split into two entries - we need a new resource */
> if (!new_res) {
>- ret = -ENOMEM;
>- break;
>+ new_res = alloc_resource(GFP_ATOMIC);
>+ if (!new_res) {
>+ alloc_nofail = true;
>+ write_unlock(&resource_lock);
>+ goto retry;
>+ }
> }
> new_res->name = res->name;
> new_res->start = end + 1;
>@@ -1339,9 +1348,8 @@ int release_mem_region_adjustable(struct resource *parent,
> new_res->sibling = res->sibling;
> new_res->child = NULL;
>
>- ret = __adjust_resource(res, res->start,
>- start - res->start);
>- if (ret)
>+ if (WARN_ON_ONCE(__adjust_resource(res, res->start,
>+ start - res->start)))
> break;
> res->sibling = new_res;
> new_res = NULL;
>@@ -1352,7 +1360,6 @@ int release_mem_region_adjustable(struct resource *parent,
>
> write_unlock(&resource_lock);
> free_resource(new_res);
>- return ret;
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
>diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>index baded53b9ff92..4c47b68a9f4b5 100644
>--- a/mm/memory_hotplug.c
>+++ b/mm/memory_hotplug.c
>@@ -1724,26 +1724,6 @@ void try_offline_node(int nid)
> }
> EXPORT_SYMBOL(try_offline_node);
>
>-static void __release_memory_resource(resource_size_t start,
>- resource_size_t size)
>-{
>- int ret;
>-
>- /*
>- * When removing memory in the same granularity as it was added,
>- * this function never fails. It might only fail if resources
>- * have to be adjusted or split. We'll ignore the error, as
>- * removing of memory cannot fail.
>- */
>- ret = release_mem_region_adjustable(&iomem_resource, start, size);
>- if (ret) {
>- resource_size_t endres = start + size - 1;
>-
>- pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
>- &start, &endres, ret);
>- }
>-}
>-
> static int __ref try_remove_memory(int nid, u64 start, u64 size)
> {
> int rc = 0;
>@@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
> memblock_remove(start, size);
> }
>
>- __release_memory_resource(start, size);
>+ release_mem_region_adjustable(&iomem_resource, start, size);
>
Seems the only user of release_mem_region_adjustable() is here, can we move
iomem_resource into the function body? Actually, we don't iterate the resource
tree from any level. We always start from the root.
> try_offline_node(nid);
>
>--
>2.26.2
--
Wei Yang
Help you, Help me
>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>> {
>> int rc = 0;
>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>> memblock_remove(start, size);
>> }
>>
>> - __release_memory_resource(start, size);
>> + release_mem_region_adjustable(&iomem_resource, start, size);
>>
>
> Seems the only user of release_mem_region_adjustable() is here, can we move
> iomem_resource into the function body? Actually, we don't iterate the resource
> tree from any level. We always start from the root.
You mean, making iomem_resource implicit? I can spot that something
similar was done for
#define devm_release_mem_region(dev, start, n) \
__devm_release_region(dev, &iomem_resource, (start), (n))
I'll send an addon patch for that, ok? - thanks.
--
Thanks,
David / dhildenb
On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>
>>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>> {
>>> int rc = 0;
>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>> memblock_remove(start, size);
>>> }
>>>
>>> - __release_memory_resource(start, size);
>>> + release_mem_region_adjustable(&iomem_resource, start, size);
>>>
>>
>> Seems the only user of release_mem_region_adjustable() is here, can we move
>> iomem_resource into the function body? Actually, we don't iterate the resource
>> tree from any level. We always start from the root.
>
>You mean, making iomem_resource implicit? I can spot that something
>similar was done for
>
>#define devm_release_mem_region(dev, start, n) \
> __devm_release_region(dev, &iomem_resource, (start), (n))
>
What I prefer is remove iomem_resource from the parameter list. Just use is in
the function body.
For the example you listed, __release_region() would have varies of *parent*,
which looks reasonable to keep it here.
>I'll send an addon patch for that, ok? - thanks.
>
>--
>Thanks,
>
>David / dhildenb
--
Wei Yang
Help you, Help me
On 15.09.20 11:06, Wei Yang wrote:
> On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>>
>>>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>> {
>>>> int rc = 0;
>>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>> memblock_remove(start, size);
>>>> }
>>>>
>>>> - __release_memory_resource(start, size);
>>>> + release_mem_region_adjustable(&iomem_resource, start, size);
>>>>
>>>
>>> Seems the only user of release_mem_region_adjustable() is here, can we move
>>> iomem_resource into the function body? Actually, we don't iterate the resource
>>> tree from any level. We always start from the root.
>>
>> You mean, making iomem_resource implicit? I can spot that something
>> similar was done for
>>
>> #define devm_release_mem_region(dev, start, n) \
>> __devm_release_region(dev, &iomem_resource, (start), (n))
>>
>
> What I prefer is remove iomem_resource from the parameter list. Just use is in
> the function body.
>
> For the example you listed, __release_region() would have varies of *parent*,
> which looks reasonable to keep it here.
Yeah I got that ("making iomem_resource implicit"), as I said:
>> I'll send an addon patch for that, ok? - thanks.
--
Thanks,
David / dhildenb
On Tue, Sep 15, 2020 at 11:15:53AM +0200, David Hildenbrand wrote:
>On 15.09.20 11:06, Wei Yang wrote:
>> On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>>>
>>>>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>>> {
>>>>> int rc = 0;
>>>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>>> memblock_remove(start, size);
>>>>> }
>>>>>
>>>>> - __release_memory_resource(start, size);
>>>>> + release_mem_region_adjustable(&iomem_resource, start, size);
>>>>>
>>>>
>>>> Seems the only user of release_mem_region_adjustable() is here, can we move
>>>> iomem_resource into the function body? Actually, we don't iterate the resource
>>>> tree from any level. We always start from the root.
>>>
>>> You mean, making iomem_resource implicit? I can spot that something
>>> similar was done for
>>>
>>> #define devm_release_mem_region(dev, start, n) \
>>> __devm_release_region(dev, &iomem_resource, (start), (n))
>>>
>>
>> What I prefer is remove iomem_resource from the parameter list. Just use is in
>> the function body.
>>
>> For the example you listed, __release_region() would have varies of *parent*,
>> which looks reasonable to keep it here.
>
>Yeah I got that ("making iomem_resource implicit"), as I said:
>
Thanks
>>> I'll send an addon patch for that, ok? - thanks.
>
>--
>Thanks,
>
>David / dhildenb
--
Wei Yang
Help you, Help me