Merge "Purge linker block allocators before leaving linker" am: e930e10935
am: 14355943ed
Change-Id: Icee442e23f0720477f056d0cfda5d836325c7d3f
diff --git a/linker/linker.cpp b/linker/linker.cpp
index d0c740b..428dd25 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -536,6 +536,10 @@
allocator_.free(ptr);
}
+ static void purge() {
+ allocator_.purge();
+ }
+
private:
static LinkerBlockAllocator allocator_;
};
@@ -553,6 +557,10 @@
static void free(T* ptr) {
SizeBasedAllocator<sizeof(T)>::free(ptr);
}
+
+ static void purge() {
+ SizeBasedAllocator<sizeof(T)>::purge();
+ }
};
class LoadTask {
@@ -2074,6 +2082,8 @@
ns == nullptr ? "(null)" : ns->get_name(),
ns);
+ auto purge_guard = android::base::make_scope_guard([&]() { purge_unused_memory(); });
+
auto failure_guard = android::base::make_scope_guard(
[&]() { LD_LOG(kLogDlopen, "... dlopen failed: %s", linker_get_error_buffer()); });
@@ -4069,3 +4079,17 @@
}
return it->second;
}
+
+void purge_unused_memory() {
+ // For now, we only purge the memory used by LoadTask because we know those
+ // are temporary objects.
+ //
+ // Purging other LinkerBlockAllocator hardly yields much because they hold
+ // information about namespaces and opened libraries, which are not freed
+ // when the control leaves the linker.
+ //
+ // Purging BionicAllocator may give us a few dirty pages back, but those pages
+ // would be already zeroed out, so they compress easily in ZRAM. Therefore,
+ // it is not worth munmap()'ing those pages.
+ TypeBasedAllocator<LoadTask>::purge();
+}
diff --git a/linker/linker.h b/linker/linker.h
index 91d3ddf..964c266 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -186,3 +186,5 @@
void increment_dso_handle_reference_counter(void* dso_handle);
void decrement_dso_handle_reference_counter(void* dso_handle);
+
+void purge_unused_memory();
diff --git a/linker/linker_block_allocator.cpp b/linker/linker_block_allocator.cpp
index d72cad3..fdb4c85 100644
--- a/linker/linker_block_allocator.cpp
+++ b/linker/linker_block_allocator.cpp
@@ -55,7 +55,8 @@
: block_size_(
round_up(block_size < sizeof(FreeBlockInfo) ? sizeof(FreeBlockInfo) : block_size, 16)),
page_list_(nullptr),
- free_block_list_(nullptr)
+ free_block_list_(nullptr),
+ allocated_(0)
{}
void* LinkerBlockAllocator::alloc() {
@@ -76,6 +77,8 @@
memset(block_info, 0, block_size_);
+ ++allocated_;
+
return block_info;
}
@@ -104,6 +107,8 @@
block_info->num_free_blocks = 1;
free_block_list_ = block_info;
+
+ --allocated_;
}
void LinkerBlockAllocator::protect_all(int prot) {
@@ -154,3 +159,18 @@
abort();
}
+
+void LinkerBlockAllocator::purge() {
+ if (allocated_) {
+ return;
+ }
+
+ LinkerBlockAllocatorPage* page = page_list_;
+ while (page) {
+ LinkerBlockAllocatorPage* next = page->next;
+ munmap(page, kAllocateSize);
+ page = next;
+ }
+ page_list_ = nullptr;
+ free_block_list_ = nullptr;
+}
diff --git a/linker/linker_block_allocator.h b/linker/linker_block_allocator.h
index 0c54b93..8ae4094 100644
--- a/linker/linker_block_allocator.h
+++ b/linker/linker_block_allocator.h
@@ -50,6 +50,9 @@
void free(void* block);
void protect_all(int prot);
+ // Purge all pages if all previously allocated blocks have been freed.
+ void purge();
+
private:
void create_new_page();
LinkerBlockAllocatorPage* find_page(void* block);
@@ -57,6 +60,7 @@
size_t block_size_;
LinkerBlockAllocatorPage* page_list_;
void* free_block_list_;
+ size_t allocated_;
DISALLOW_COPY_AND_ASSIGN(LinkerBlockAllocator);
};
diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index b0c27dc..7486cd7 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -503,6 +503,10 @@
fflush(stdout);
#endif
+ // We are about to hand control over to the executable loaded. We don't want
+ // to leave dirty pages behind unnecessarily.
+ purge_unused_memory();
+
ElfW(Addr) entry = exe_info.entry_point;
TRACE("[ Ready to execute \"%s\" @ %p ]", si->get_realpath(), reinterpret_cast<void*>(entry));
return entry;