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SubjectRe: [PATCH] mm/swap_slots.c: don't reset the cache slot after use
On Mon,  9 Mar 2020 17:09:40 +0800 Wei Yang <richard.weiyang@linux.alibaba.com> wrote:

> Currently we would clear the cache slot if it is used. While this is not
> necessary, since this entry would not be used until refilled.
>
> Leave it untouched and assigned the value directly to entry which makes
> the code little more neat.
>
> Also this patch merges the else and if, since this is the only case we
> refill and repeat swap cache.

cc Tim, who can hopefully remember how this code works ;)

> --- a/mm/swap_slots.c
> +++ b/mm/swap_slots.c
> @@ -309,7 +309,7 @@ int free_swap_slot(swp_entry_t entry)
>
> swp_entry_t get_swap_page(struct page *page)
> {
> - swp_entry_t entry, *pentry;
> + swp_entry_t entry;
> struct swap_slots_cache *cache;
>
> entry.val = 0;
> @@ -336,13 +336,10 @@ swp_entry_t get_swap_page(struct page *page)
> if (cache->slots) {
> repeat:
> if (cache->nr) {
> - pentry = &cache->slots[cache->cur++];
> - entry = *pentry;
> - pentry->val = 0;
> + entry = cache->slots[cache->cur++];
> cache->nr--;
> - } else {
> - if (refill_swap_slots_cache(cache))
> - goto repeat;
> + } else if (refill_swap_slots_cache(cache)) {
> + goto repeat;
> }
> }
> mutex_unlock(&cache->alloc_lock);
> --
> 2.20.1 (Apple Git-117)

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