linux-kernel - [PATCH net-next] page pool: not return page to alloc cache during pool destruction

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Date:   Thu, 15 Jun 2023 09:36:45 +0800
From:   Liang Chen <liangchen.linux@...il.com>
To:     hawk@...nel.org, ilias.apalodimas@...aro.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, Liang Chen <liangchen.linux@...il.com>
Subject: [PATCH net-next] page pool: not return page to alloc cache during pool destruction

When destroying a page pool, the alloc cache and recycle ring are emptied.
If there are inflight pages, the retry process will periodically check the
recycle ring for recently returned pages, but not the alloc cache (alloc
cache is only emptied once). As a result, any pages returned to the alloc
cache after the page pool destruction will be stuck there and cause the
retry process to continuously look for inflight pages and report warnings.

To safeguard against this situation, any pages returning to the alloc cache
after pool destruction should be prevented.

Signed-off-by: Liang Chen <liangchen.linux@...il.com>
---
 net/core/page_pool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index a3e12a61d456..76255313d349 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -595,7 +595,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
 			page_pool_dma_sync_for_device(pool, page,
 						      dma_sync_size);

-		if (allow_direct && in_softirq() &&
+		if (allow_direct && in_softirq() && !pool->destroy_cnt &&
 		    page_pool_recycle_in_cache(page, pool))
 			return NULL;

-- 
2.31.1