From ac2aca2817ca10ad30f86d0d3caa41ea8cc4f0f0 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 23 Feb 2012 01:37:19 -0500
Subject: [PATCH] um: uml_dup_mmap() relies on ->mmap_sem being held, but
activate_mm() doesn't hold it
... while calling uml_dup_mmap()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/um/include/asm/mmu_context.h | 11 +++++++++--
arch/um/kernel/skas/mmu.c | 2 +-
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 591b3d8d7614..aa4a743dc4ab 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -9,7 +9,7 @@
#include <linux/sched.h>
#include <asm/mmu.h>
-extern void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm);
+extern void uml_setup_stubs(struct mm_struct *mm);
extern void arch_exit_mmap(struct mm_struct *mm);
#define deactivate_mm(tsk,mm) do { } while (0)
@@ -23,7 +23,9 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
* when the new ->mm is used for the first time.
*/
__switch_mm(&new->context.id);
- arch_dup_mmap(old, new);
+ down_write(&new->mmap_sem);
+ uml_setup_stubs(new);
+ up_write(&new->mmap_sem);
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
@@ -39,6 +41,11 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
}
}
+static inline void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ uml_setup_stubs(mm);
+}
+
static inline void enter_lazy_tlb(struct mm_struct *mm,
struct task_struct *tsk)
{
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index db2ef422c1b8..4947b319f53a 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -101,7 +101,7 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
return ret;
}
-void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+void uml_setup_stubs(struct mm_struct *mm)
{
struct page **pages;
int err, ret;
--
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