| Message ID | 20201009133059.58407-1-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/swap_state: Skip meaningless swap cache readahead when ra_info.win == 0 | expand |
On Fri, 9 Oct 2020 09:30:59 -0400 Miaohe Lin <linmiaohe@huawei.com> wrote: > 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. > > > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -839,7 +839,7 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask, > swp_entry_t entry; > unsigned int i; > bool page_allocated; > - struct vma_swap_readahead ra_info = {0,}; > + struct vma_swap_readahead ra_info = {1,}; > > swap_ra_info(vmf, &ra_info); > if (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. Otherwise, let's modernify that struct initializer: --- a/mm/swap_state.c~mm-swap_state-skip-meaningless-swap-cache-readahead-when-ra_infowin-==-0-fix +++ 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 = {1,}; + struct vma_swap_readahead ra_info = { + .win = 1, + }; swap_ra_info(vmf, &ra_info); if (ra_info.win == 1)
diff --git a/mm/swap_state.c b/mm/swap_state.c index ee465827420e..b9013c3f94c9 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -839,7 +839,7 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask, swp_entry_t entry; unsigned int i; bool page_allocated; - struct vma_swap_readahead ra_info = {0,}; + struct vma_swap_readahead ra_info = {1,}; swap_ra_info(vmf, &ra_info); if (ra_info.win == 1)
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. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/swap_state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)