Hi Kairui,
On Mon, 5 Feb 2024 19:09:59 +0800 Kairui Song <ryncsn@xxxxxxxxx> wrote:
[...]
> mm/memory.c | 19 +++++++++++++++++++
> mm/swap.h | 5 +++++
> mm/swapfile.c | 16 ++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 7e1f4849463a..fd7c55a292f1 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3867,6 +3867,20 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> if (!folio) {
> if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
> __swap_count(entry) == 1) {
> + /*
> + * With swap count == 1, after we read the entry,
> + * other threads could finish swapin first, free
> + * the entry, then swapout the modified page using
> + * the same entry. Now the content we just read is
> + * stalled, and it's undetectable as pte_same()
> + * returns true due to entry reuse.
> + *
> + * So pin the swap entry using the cache flag even
> + * cache is not used.
> + */
> + if (swapcache_prepare(entry))
> + goto out;
> +
I'm getting below build error after this patch. I guess maybe the code need to
take care of CONFIG_SWAP unset case?
.../mm/memory.c: In function 'do_swap_page':
.../mm/memory.c:4004:8: error: implicit declaration of function 'swapcache_prepare'; did you mean 'swapcache_clear'? [-Werror=implicit-function-declaration]
4004 | if (swapcache_prepare(entry))
| ^~~~~~~~~~~~~~~~~
| swapcache_clear
Thanks,
SJ
[...]
