uml: fix mm_context memory leak
[ Spotted by Miklos ]
Fix a memory leak in init_new_context. The struct page ** buffer allocated
for install_special_mapping was never recorded, and thus leaked when the
mm_struct was freed. Fix it by saving the pointer in mm_context_t and freeing
it in arch_exit_mmap.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/include/um_mmu.h b/arch/um/include/um_mmu.h
index 82865fc..f575ff9 100644
--- a/arch/um/include/um_mmu.h
+++ b/arch/um/include/um_mmu.h
@@ -13,6 +13,7 @@
typedef struct mm_context {
struct mm_id id;
struct uml_ldt ldt;
+ struct page **stub_pages;
} mm_context_t;
extern void __switch_mm(struct mm_id * mm_idp);
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 78b3e9f..0cd9a7a 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -91,6 +91,8 @@
goto out_free;
}
+ to_mm->stub_pages = NULL;
+
return 0;
out_free:
@@ -126,6 +128,7 @@
pages[0] = virt_to_page(&__syscall_stub_start);
pages[1] = virt_to_page(mm->context.id.stack);
+ mm->context.stub_pages = pages;
/* dup_mmap already holds mmap_sem */
err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
@@ -147,6 +150,8 @@
{
pte_t *pte;
+ if (mm->context.stub_pages != NULL)
+ kfree(mm->context.stub_pages);
pte = virt_to_pte(mm, STUB_CODE);
if (pte != NULL)
pte_clear(mm, STUB_CODE, pte);
