Hi Mel Gorman and all.
I have read do_mmap_pgoff and mmap_region more than one hour,
but still can't catch sense about below code in mmap_region:
"
/* Clear old maps */
error = -ENOMEM;
munmap_back:
if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
if (do_munmap(mm, addr, len))
return -ENOMEM;
goto munmap_back;
}
"
How can we just do_munmap overlapping vma without check its vm_flags
and new vma's vm_flags? I must miss some important things, but I can't
figure out.
You give below comment about the code in "understand the linux memory manager":)
"
If a VMA was found and it is part of the new mmapping, this removes the
old mmapping because the new one will cover both
"
But if new mmapping has different vm_flags or others' property, how
can we just say the new one will cover both?
I appreicate any clue and explanation about this headache question.
Thanks.
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