linux-kernel - [PATCH] fs: quota: Replace GFP_ATOMIC with GFP_KERNEL in dquot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Mon,  9 Apr 2018 22:31:19 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     jack@...e.com
Cc:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] fs: quota: Replace GFP_ATOMIC with GFP_KERNEL in dquot_init

dquot_init() is never called in atomic context.
This function is only set as a parameter of fs_initcall().

Despite never getting called from atomic context,
dquot_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@...il.com>
---
 fs/quota/dquot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 8381db9..d6e111e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2944,7 +2944,7 @@ static int __init dquot_init(void)
 			NULL);

 	order = 0;
-	dquot_hash = (struct hlist_head *)__get_free_pages(GFP_ATOMIC, order);
+	dquot_hash = (struct hlist_head *)__get_free_pages(GFP_KERNEL, order);
 	if (!dquot_hash)
 		panic("Cannot create dquot hash table");

-- 
1.9.1