On Tue, Sep 22, 2020 at 05:48:46PM +0200, Oleg Nesterov wrote: > > However since I didn't change this logic in this patch, it probably means > > this > > bug is also in the original code before this series... I'm thinking maybe I > > should prepare a standalone patch to clear the swp_entry_t and cc stable. > > Well, if copy_one_pte(src_pte) hits a swap entry and returns entry.val != 0, > then > pte_none(*src_pte) is not possible after restart? This means that > copy_one_pte() > will be called at least once.
Note that we've released the page table locks, so afaict the old swp entry can be gone under us when we go back to the "do" loop... :) Extremely corner case, but maybe still good to fix, extra clearness as a (good) side effect. -- Peter Xu
