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Subject[RFC PATCH 3/9] mm/zbud: remove lru from zbud_header
Date
zbud_pool has an lru list for tracking zbud pages and they are strung
together via zhdr->lru. If we reuse page->lru for linking zbud pages
instead of it, the lru field in zbud_header can be dropped.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>
---
mm/zbud.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/mm/zbud.c b/mm/zbud.c
index 0f5add0..a2390f6 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -100,13 +100,11 @@ struct zbud_pool {
* struct zbud_header - zbud page metadata occupying the first chunk of each
* zbud page.
* @buddy: links the zbud page into the unbuddied lists in the pool
- * @lru: links the zbud page into the lru list in the pool
* @first_chunks: the size of the first buddy in chunks, 0 if free
* @last_chunks: the size of the last buddy in chunks, 0 if free
*/
struct zbud_header {
struct list_head buddy;
- struct list_head lru;
unsigned int first_chunks;
unsigned int last_chunks;
bool under_reclaim;
@@ -224,7 +222,7 @@ static struct zbud_header *init_zbud_page(struct page *page)
zhdr->first_chunks = 0;
zhdr->last_chunks = 0;
INIT_LIST_HEAD(&zhdr->buddy);
- INIT_LIST_HEAD(&zhdr->lru);
+ INIT_LIST_HEAD(&page->lru);
zhdr->under_reclaim = 0;
return zhdr;
}
@@ -352,6 +350,7 @@ int zbud_alloc(struct zbud_pool *pool, size_t size, gfp_t gfp,
if (!list_empty(&pool->unbuddied[i])) {
zhdr = list_first_entry(&pool->unbuddied[i],
struct zbud_header, buddy);
+ page = virt_to_page(zhdr);
list_del(&zhdr->buddy);
goto found;
}
@@ -382,9 +381,9 @@ found:
}

/* Add/move zbud page to beginning of LRU */
- if (!list_empty(&zhdr->lru))
- list_del(&zhdr->lru);
- list_add(&zhdr->lru, &pool->lru);
+ if (!list_empty(&page->lru))
+ list_del(&page->lru);
+ list_add(&page->lru, &pool->lru);

*handle = encode_handle(zhdr, bud);
spin_unlock(&pool->lock);
@@ -405,10 +404,12 @@ found:
void zbud_free(struct zbud_pool *pool, unsigned long handle)
{
struct zbud_header *zhdr;
+ struct page *page;
int freechunks;

spin_lock(&pool->lock);
zhdr = handle_to_zbud_header(handle);
+ page = virt_to_page(zhdr);

/* If first buddy, handle will be page aligned */
if ((handle - ZHDR_SIZE_ALIGNED) & ~PAGE_MASK)
@@ -426,7 +427,7 @@ void zbud_free(struct zbud_pool *pool, unsigned long handle)
/* Remove from existing unbuddied list */
list_del(&zhdr->buddy);
/* zbud page is empty, free */
- list_del(&zhdr->lru);
+ list_del(&page->lru);
free_zbud_page(zhdr);
pool->pages_nr--;
} else {
@@ -479,6 +480,7 @@ void zbud_free(struct zbud_pool *pool, unsigned long handle)
int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries)
{
int i, ret, freechunks;
+ struct page *page;
struct zbud_header *zhdr;
unsigned long first_handle, last_handle;

@@ -489,8 +491,9 @@ int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries)
return -EINVAL;
}
for (i = 0; i < retries; i++) {
- zhdr = list_tail_entry(&pool->lru, struct zbud_header, lru);
- list_del(&zhdr->lru);
+ page = list_tail_entry(&pool->lru, struct page, lru);
+ zhdr = page_address(page);
+ list_del(&page->lru);
list_del(&zhdr->buddy);
/* Protect zbud page against free */
zhdr->under_reclaim = true;
@@ -537,7 +540,7 @@ next:
}

/* add to beginning of LRU */
- list_add(&zhdr->lru, &pool->lru);
+ list_add(&page->lru, &pool->lru);
}
spin_unlock(&pool->lock);
return -EAGAIN;
--
1.9.1


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