[PATCH 1/2] mm: Introducing arch_remap hook

[Laurent Dufour]

Some architecture would like to be triggered when a memory area is moved
through the mremap system call.

This patch is introducing a new arch_remap mm hook which is placed in the
path of mremap, and is called before the old area is unmapped (and the
arch_unmap hook is called).

To no break the build, this patch adds the empty hook definition to the
architectures that were not using the generic hook's definition.

Signed-off-by: Laurent Dufour <ldufour at linux.vnet.ibm.com>
---
 arch/s390/include/asm/mmu_context.h      | 6 ++++++
 arch/um/include/asm/mmu_context.h        | 5 +++++
 arch/unicore32/include/asm/mmu_context.h | 6 ++++++
 arch/x86/include/asm/mmu_context.h       | 6 ++++++
 include/asm-generic/mm_hooks.h           | 6 ++++++
 mm/mremap.c                              | 9 +++++++--
 6 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 8fb3802f8fad..ddd861a490ba 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -131,4 +131,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
 {
 }
 
+static inline void arch_remap(struct mm_struct *mm,
+			      unsigned long old_start, unsigned long old_end,
+			      unsigned long new_start, unsigned long new_end)
+{
+}
+
 #endif /* __S390_MMU_CONTEXT_H */
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 941527e507f7..f499b017c1f9 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -27,6 +27,11 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
 				     struct vm_area_struct *vma)
 {
 }
+static inline void arch_remap(struct mm_struct *mm,
+			      unsigned long old_start, unsigned long old_end,
+			      unsigned long new_start, unsigned long new_end)
+{
+}
 /*
  * end asm-generic/mm_hooks.h functions
  */
diff --git a/arch/unicore32/include/asm/mmu_context.h b/arch/unicore32/include/asm/mmu_context.h
index 1cb5220afaf9..39a0a553172e 100644
--- a/arch/unicore32/include/asm/mmu_context.h
+++ b/arch/unicore32/include/asm/mmu_context.h
@@ -97,4 +97,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
 {
 }
 
+static inline void arch_remap(struct mm_struct *mm,
+			      unsigned long old_start, unsigned long old_end,
+			      unsigned long new_start, unsigned long new_end)
+{
+}
+
 #endif
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 883f6b933fa4..75cb71f4be1e 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -172,4 +172,10 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 		mpx_notify_unmap(mm, vma, start, end);
 }
 
+static inline void arch_remap(struct mm_struct *mm,
+			      unsigned long old_start, unsigned long old_end,
+			      unsigned long new_start, unsigned long new_end)
+{
+}
+
 #endif /* _ASM_X86_MMU_CONTEXT_H */
diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h
index 866aa461efa5..e507f4783a5b 100644
--- a/include/asm-generic/mm_hooks.h
+++ b/include/asm-generic/mm_hooks.h
@@ -26,4 +26,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
 {
 }
 
+static inline void arch_remap(struct mm_struct *mm,
+			      unsigned long old_start, unsigned long old_end,
+			      unsigned long new_start, unsigned long new_end)
+{
+}
+
 #endif	/* _ASM_GENERIC_MM_HOOKS_H */
diff --git a/mm/mremap.c b/mm/mremap.c
index 57dadc025c64..6a409ca09425 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -25,6 +25,7 @@
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
 
 #include "internal.h"
 
@@ -286,8 +287,12 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 		old_len = new_len;
 		old_addr = new_addr;
 		new_addr = -ENOMEM;
-	} else if (vma->vm_file && vma->vm_file->f_op->mremap)
-		vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+	} else {
+		if (vma->vm_file && vma->vm_file->f_op->mremap)
+			vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+		arch_remap(mm, old_addr, old_addr+old_len,
+			   new_addr, new_addr+new_len);
+	}
 
 	/* Conceal VM_ACCOUNT so old reservation is not undone */
 	if (vm_flags & VM_ACCOUNT) {
-- 
1.9.1