| Message ID | 1488985872-22447-1-git-send-email-yang.zhong@intel.com |
|---|---|
| State | New |
| Headers | show |
On 03/08/2017 12:11 PM, 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> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > memory.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/memory.c b/memory.c > index 284894b..799ca4c 100644 > --- a/memory.c > +++ b/memory.c > @@ -2422,8 +2422,10 @@ 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) { > - as->ref_count++; > + if (root == as->root) { > + if (as->malloced) { > + as->ref_count++; > + } > return as; > } > } >
On 08/03/2017 12:17, Philippe Mathieu-Daudé wrote: > On 03/08/2017 12:11 PM, 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> > > Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > >> --- >> memory.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/memory.c b/memory.c >> index 284894b..799ca4c 100644 >> --- a/memory.c >> +++ b/memory.c >> @@ -2422,8 +2422,10 @@ 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) { >> - as->ref_count++; >> + if (root == as->root) { >> + if (as->malloced) { >> + as->ref_count++; >> + } >> return as; >> } >> } >> This is wrong. 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
diff --git a/memory.c b/memory.c index 284894b..799ca4c 100644 --- a/memory.c +++ b/memory.c @@ -2422,8 +2422,10 @@ 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) { - as->ref_count++; + if (root == as->root) { + if (as->malloced) { + as->ref_count++; + } return as; } }
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 | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)