mm/swap_state: Skip meaningless swap cache readahead when ra_info.win == 0
Quoted 11 lines · Andrew Morton
Quoted 5 lines · On Fri, 9 Oct 2020 09:30:59 -0400 Miaohe Lin <[email protected]> wrote:
swap_ra_info()may leavera_infountouched innon_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.Looks right. But I think it would be better to fix this in
swap_ra_info()- make it more consistent in its return state.
I think modernify the struct initializer is better because it means we have to swap in one page at least. Many thanks.
Quoted 17 lines
Otherwise, let's modernify that struct initializer:
mm/swap_state.c renamed from mm/swap_state.c~mm-swap_state-skip-meaningless-swap-cache-readahead-when-ra_infowin-==-0-fix +3
-1@@ -839,7 +839,9 @@ static struct page *swap_vma_readahead(sswp_entry_t entry;unsigned int i;bool page_allocated; -struct vma_swap_readahead ra_info = {1 ,}; +struct vma_swap_readahead ra_info = { + .win =1 , + };swap_ra_info (vmf, &ra_info);if (ra_info.win ==1 )_