On Fri, 15 Nov 2019 12:58:08 +0100 Thomas Hellström (VMware) <thomas_os@xxxxxxxxxxxx> wrote: > A huge pud page can theoretically be faulted in racing with pmd_alloc() > in __handle_mm_fault(). That will lead to pmd_alloc() returning an > invalid pmd pointer. Fix this by adding a pud_trans_unstable() function > similar to pmd_trans_unstable() and check whether the pud is really stable > before using the pmd pointer. > > Race: > Thread 1: Thread 2: Comment > create_huge_pud() Fallback - not taken. > create_huge_pud() Taken. > pmd_alloc() Returns an invalid pointer. What are the user-visible runtime effects of this change? Is a -stable backport warranted?
