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mm: fix expression to determine which vma-s can be shared

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Currently only addresses are compared. It's obviously not enough.

* First of all the parent vma must be private.
* Both vma-s must have the identical set of MAP_GROWSDOWN and MAP_FILES
  flags.
* Both vma-s must be linked to the same file.

https://bugzilla.openvz.org/show_bug.cgi?id=2824
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin 2013-11-22 18:19:23 +04:00 committed by Pavel Emelyanov
parent 7659c995f5
commit 57d25e7cea
1 changed files with 17 additions and 7 deletions
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24
cr-restore.c
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@ -234,14 +234,24 @@ static int map_private_vma(pid_t pid, struct vma_area *vma, void *tgt_addr,
if (p->vma.start > vma->vma.start)
break;
if (p->vma.end == vma->vma.end &&
p->vma.start == vma->vma.start) {
pr_info("COW 0x%016"PRIx64"-0x%016"PRIx64" 0x%016"PRIx64" vma\n",
vma->vma.start, vma->vma.end, vma->vma.pgoff);
paddr = decode_pointer(vma->premmaped_addr);
break;
}
if (!vma_priv(&p->vma))
continue;
if (p->vma.end != vma->vma.end ||
p->vma.start != vma->vma.start)
continue;
/* Check flags, which must be identical for both vma-s */
if ((vma->vma.flags ^ p->vma.flags) & (MAP_GROWSDOWN | MAP_ANONYMOUS))
break;
if (!(vma->vma.flags & MAP_ANONYMOUS) &&
vma->vma.shmid != p->vma.shmid)
break;
pr_info("COW 0x%016"PRIx64"-0x%016"PRIx64" 0x%016"PRIx64" vma\n",
vma->vma.start, vma->vma.end, vma->vma.pgoff);
paddr = decode_pointer(vma->premmaped_addr);
}
*pvma = p;