* [Qemu-devel] [PATCH v2] memory: reduce heap Rss size around 3M
@ 2017-03-10 13:44 Yang Zhong
2017-03-10 8:40 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Yang Zhong @ 2017-03-10 13:44 UTC (permalink / raw)
To: qemu-devel; +Cc: pbonzini, anthony.xu, Yang Zhong
Since cpu-memory and memory have same address space,one malloced
memory is enough. This patch will skip memory malloc for memory
address space,which will reduce around 3M physical memory in heap.
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index 284894b..6af80e7 100644
--- a/memory.c
+++ b/memory.c
@@ -2422,7 +2422,7 @@ AddressSpace *address_space_init_shareable(MemoryRegion *root, const char *name)
AddressSpace *as;
QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {
- if (root == as->root && as->malloced) {
+ if (root == as->root) {
as->ref_count++;
return as;
}
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [Qemu-devel] [PATCH v2] memory: reduce heap Rss size around 3M
2017-03-10 13:44 [Qemu-devel] [PATCH v2] memory: reduce heap Rss size around 3M Yang Zhong
@ 2017-03-10 8:40 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2017-03-10 8:40 UTC (permalink / raw)
To: Yang Zhong, qemu-devel; +Cc: anthony.xu
On 10/03/2017 14:44, Yang Zhong wrote:
> Since cpu-memory and memory have same address space,one malloced
> memory is enough. This patch will skip memory malloc for memory
> address space,which will reduce around 3M physical memory in heap.
>
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> ---
> memory.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/memory.c b/memory.c
> index 284894b..6af80e7 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -2422,7 +2422,7 @@ AddressSpace *address_space_init_shareable(MemoryRegion *root, const char *name)
> AddressSpace *as;
>
> QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {
> - if (root == as->root && as->malloced) {
> + if (root == as->root) {
> as->ref_count++;
> return as;
> }
>
This has the same problem as v1.
If as->malloced is false, the AddressSpace might be embedded in another
struct. This other struct could be freed when as->ref_count is still
greater than 0, causing a use-after-free bug.
Paolo
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2017-03-10 8:40 ` Paolo Bonzini
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