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page_pool: refill page when alloc.count of pool is zero 

"do {} while" in page_pool_refill_alloc_cache will always
refill page once whether refill is true or false, and whether
alloc.count of pool is less than PP_ALLOC_CACHE_REFILL or not
this is wrong, and will cause overflow of pool->alloc.cache

the caller of __page_pool_get_cached should provide guarantee
that pool->alloc.cache is safe to access, so in_serving_softirq
should be removed as suggested by Jesper Dangaard Brouer in
https://patchwork.ozlabs.org/patch/1233713/

so fix this issue by calling page_pool_refill_alloc_cache()
only when pool->alloc.count is zero

Fixes: 44768decb7 ("page_pool: handle page recycle for NUMA_NO_NODE condition")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: hongrongxuan <hongrongxuan@huawei.com>
This commit is contained in:
Li RongQing 2020-02-11 10:13:44 +08:00 committed by Jianping Liu
parent 37ca71f4f7
commit 9e33173b6b
1 changed files with 8 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
net/core/page_pool.c
View File

@ -99,8 +99,7 @@ EXPORT_SYMBOL(page_pool_create);
static void __page_pool_return_page(struct page_pool *pool, struct page *page);
noinline
static struct page *page_pool_refill_alloc_cache(struct page_pool *pool,
bool refill)
static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
{
struct ptr_ring *r = &pool->ring;
struct page *page;
@ -141,8 +140,7 @@ static struct page *page_pool_refill_alloc_cache(struct page_pool *pool,
page = NULL;
break;
}
} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL &&
refill);
} while (pool->alloc.count < PP_ALLOC_CACHE_REFILL);
/* Return last page */
if (likely(pool->alloc.count > 0))
@ -155,20 +153,16 @@ static struct page *page_pool_refill_alloc_cache(struct page_pool *pool,
/* fast path */
static struct page *__page_pool_get_cached(struct page_pool *pool)
{
bool refill = false;
struct page *page;
/* Test for safe-context, caller should provide this guarantee */
if (likely(in_serving_softirq())) {
if (likely(pool->alloc.count)) {
/* Fast-path */
page = pool->alloc.cache[--pool->alloc.count];
return page;
}
refill = true;
/* Caller MUST guarantee safe non-concurrent access, e.g. softirq */
if (likely(pool->alloc.count)) {
/* Fast-path */
page = pool->alloc.cache[--pool->alloc.count];
} else {
page = page_pool_refill_alloc_cache(pool);
}
page = page_pool_refill_alloc_cache(pool, refill);
return page;
}