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Subject[PATCH v5 2/3] mm: New arch_remap hook
Date
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).

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
include/linux/mm-arch-hooks.h | 9 +++++++++
mm/mremap.c | 17 +++++++++++------
2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/linux/mm-arch-hooks.h b/include/linux/mm-arch-hooks.h
index 63005e367abd..4efc3f56e6df 100644
--- a/include/linux/mm-arch-hooks.h
+++ b/include/linux/mm-arch-hooks.h
@@ -13,4 +13,13 @@

#include <asm/mm-arch-hooks.h>

+#ifndef arch_remap
+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)
+{
+}
+#define arch_remap arch_remap
+#endif
+
#endif /* _LINUX_MM_ARCH_HOOKS_H */
diff --git a/mm/mremap.c b/mm/mremap.c
index 2dc44b1cb1df..7597af900d07 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -22,6 +22,7 @@
#include <linux/mmu_notifier.h>
#include <linux/sched/sysctl.h>
#include <linux/uaccess.h>
+#include <linux/mm-arch-hooks.h>

#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
@@ -286,13 +287,17 @@ 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) {
- err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
- if (err < 0) {
- move_page_tables(new_vma, new_addr, vma, old_addr,
- moved_len, true);
- return err;
+ } else {
+ if (vma->vm_file && vma->vm_file->f_op->mremap) {
+ err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+ if (err < 0) {
+ move_page_tables(new_vma, new_addr, vma,
+ old_addr, moved_len, true);
+ return err;
+ }
}
+ arch_remap(mm, old_addr, old_addr + old_len,
+ new_addr, new_addr + new_len);
}

/* Conceal VM_ACCOUNT so old reservation is not undone */
--
1.9.1


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