Add support for VM_NORESERVE and VM_LOCKED and remove them from
the blacklist of vm flags.
VM_NORESERVE: a vma with VM_NORESERVE may segv on a write under
low-memory, but reading it (as we do during checkpoint) is fine.
VM_LOCKED: this flag is now explicitly restored for a vma that had
this flag, using sys_mlock()
Original patch and reports by Nathan Lynch and Dan Smith.
Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
---
include/linux/checkpoint.h | 2 +-
mm/checkpoint.c | 10 ++++++++++
2 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index c338149..a796308 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -306,7 +306,7 @@ extern int restore_memory_contents(struct ckpt_ctx *ctx, struct inode *inode);
#define CKPT_VMA_NOT_SUPPORTED \
(VM_IO | VM_HUGETLB | VM_NONLINEAR | VM_PFNMAP | \
- VM_RESERVED | VM_NORESERVE | VM_HUGETLB | VM_NONLINEAR | \
+ VM_RESERVED | VM_HUGETLB | VM_NONLINEAR | \
VM_MAPPED_COPY | VM_INSERTPAGE | VM_MIXEDMAP | VM_SAO)
/* signals */
diff --git a/mm/checkpoint.c b/mm/checkpoint.c
index d1d0bcb..70300e8 100644
--- a/mm/checkpoint.c
+++ b/mm/checkpoint.c
@@ -24,6 +24,7 @@
#include <linux/shm.h>
#include <linux/proc_fs.h>
#include <linux/swap.h>
+#include <linux/syscalls.h>
#include <linux/checkpoint.h>
/*
@@ -1018,6 +1019,8 @@ static unsigned long calc_map_flags_bits(unsigned long orig_vm_flags)
vm_flags |= MAP_SHARED;
else
vm_flags |= MAP_PRIVATE;
+ if (orig_vm_flags & VM_NORESERVE)
+ vm_flags |= MAP_NORESERVE;
return vm_flags;
}
@@ -1034,6 +1037,7 @@ unsigned long generic_vma_restore(struct mm_struct *mm,
{
unsigned long vm_size, vm_start, vm_flags, vm_prot, vm_pgoff;
unsigned long addr;
+ int ret;
if (h->vm_end < h->vm_start)
return -EINVAL;
@@ -1053,6 +1057,12 @@ unsigned long generic_vma_restore(struct mm_struct *mm,
ckpt_debug("size %#lx prot %#lx flag %#lx pgoff %#lx => %#lx\n",
vm_size, vm_prot, vm_flags, vm_pgoff, addr);
+ if (h->vm_flags & VM_LOCKED && !IS_ERR((void *) addr)) {
+ ret = sys_mlock(addr, vm_size);
+ if (ret < 0)
+ addr = (unsigned long) ret;
+ }
+
return addr;
}
--
1.7.0.4
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