Messages in this thread | | | From | James Houghton <> | Date | Fri, 24 Feb 2023 10:05:11 -0800 | Subject | Re: [PATCH v2 35/46] hugetlb: add check to prevent refcount overflow via HGM |
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On Fri, Feb 24, 2023 at 9:42 AM James Houghton <jthoughton@google.com> wrote: > > > @@ -5397,7 +5397,10 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, > > } else { > > ptepage = pte_page(entry); > > hpage = compound_head(ptepage); > > - get_page(hpage); > > + if (try_get_page(hpage)) { > > + ret = -EFAULT; > > + break; > > spin_unlock(src_ptl) and spin_unlock(dst_ptl) is required here. > > I'll make sure there's a selftest that actually makes sure that > refcount overflowing is handled gracefully for v3.
And this should be !try_get_page(). This hunk was a last-minute addition to this commit; apparently I hadn't retested fork() after I made this change. Sorry! The hugetlb-hgm selftest immediately catches this problem.
- James
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