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From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: davem@davemloft.net, kafai@fb.com, weiwan@google.com,
	dsa@cumulusnetworks.com, johannes.berg@intel.com, fw@strlen.de
Cc: linux-decnet-user@lists.sourceforge.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH] net: decnet: Replace GFP_ATOMIC with GFP_KERNEL in dn_route_init
Date: Mon,  9 Apr 2018 22:10:35 +0800	[thread overview]
Message-ID: <1523283035-25639-1-git-send-email-baijiaju1990@gmail.com> (raw)

dn_route_init() is never called in atomic context.

The call chain ending up at dn_route_init() is:
[1] dn_route_init() <- decnet_init()
decnet_init() is only set as a parameter of module_init().

Despite never getting called from atomic context,
dn_route_init() calls __get_free_pages() with GFP_ATOMIC,
which waits busily for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
to avoid busy waiting and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 net/decnet/dn_route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 0bd3afd..59ed12a 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1898,7 +1898,7 @@ void __init dn_route_init(void)
 		while(dn_rt_hash_mask & (dn_rt_hash_mask - 1))
 			dn_rt_hash_mask--;
 		dn_rt_hash_table = (struct dn_rt_hash_bucket *)
-			__get_free_pages(GFP_ATOMIC, order);
+			__get_free_pages(GFP_KERNEL, order);
 	} while (dn_rt_hash_table == NULL && --order > 0);
 
 	if (!dn_rt_hash_table)
-- 
1.9.1

             reply	other threads:[~2018-04-09 14:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-09 14:10 Jia-Ju Bai [this message]
2018-04-09 14:44 ` [PATCH] net: decnet: Replace GFP_ATOMIC with GFP_KERNEL in dn_route_init Eric Dumazet
2018-04-09 14:48   ` Jia-Ju Bai

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