On 12/8/22 13:05, Peter Xu wrote:
+ /*
+ * NOTE: we don't need explicit lock here to walk the
+ * hugetlb pgtable because either (1) potential callers of
+ * hugetlb pvmw currently holds i_mmap_rwsem, or (2) the
+ * caller will not walk a hugetlb vma (e.g. ksm or uprobe).
+ * When one day this rule breaks, one will get a warning
+ * in hugetlb_walk(), and then we'll figure out what to do.
+ */
Confused. Is this documentation actually intended to refer to hugetlb_walk()
itself, or just this call site? If the former, then let's move it over
to be right before hugetlb_walk().
It is for this specific code path not hugetlb_walk().
The "holds i_mmap_rwsem" here is a true statement (not requirement) because
PVMW rmap walkers always have that. That satisfies with hugetlb_walk()
requirements already even without holding the vma lock.
It's really hard to understand. Do you have a few extra words to explain it?
I can help with actual comment wording perhaps, but I am still a bit in
the dark as to the actual meaning. :)
thanks,
--
John Hubbard
NVIDIA
