From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: mm/swap_state: skip meaningless swap cache readahead when ra_info.win == 0 swap_ra_info() may leave ra_info untouched in non_swap_entry() case as page table lock is not held. In this case, we have ra_info.nr_pte == 0 and it is meaningless to continue with swap cache readahead. Skip such ops by init ra_info.win = 1. [akpm@xxxxxxxxxxxxxxxxxxxx: clean up struct init] Link: https://lkml.kernel.org/r/20201009133059.58407-1-linmiaohe@xxxxxxxxxx Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swap_state.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/swap_state.c~mm-swap_state-skip-meaningless-swap-cache-readahead-when-ra_infowin-==-0 +++ a/mm/swap_state.c @@ -839,7 +839,9 @@ static struct page *swap_vma_readahead(s swp_entry_t entry; unsigned int i; bool page_allocated; - struct vma_swap_readahead ra_info = {0,}; + struct vma_swap_readahead ra_info = { + .win = 1, + }; swap_ra_info(vmf, &ra_info); if (ra_info.win == 1) _
