linux-kernel - [PATCH] ipc: don't allocate with GFP

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Message-Id: <1370880870-23833-1-git-send-email-sasha.levin@oracle.com>
Date:	Mon, 10 Jun 2013 12:14:30 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	akpm@...ux-foundation.org
Cc:	davidlohr.bueso@...com, riel@...hat.com, walken@...gle.com,
	linux-kernel@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] ipc: don't allocate with GFP_KERNEL inside rcu read lock

ipc_addid() is protected by a rcu read lock, which means we can't allocate
using GFP_KERNEL inside it.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---

Another option would be to call idr_preload from outside the read lock,
but that complicates the code much more than this fix. If that's the
preferred method to fix it I can resend that solution instead.

 ipc/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ipc/util.c b/ipc/util.c
index a746abb..00aca85 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -261,7 +261,7 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 	if (ids->in_use >= size)
 		return -ENOSPC;
 
-	idr_preload(GFP_KERNEL);
+	idr_preload(GFP_ATOMIC);
 
 	spin_lock_init(&new->lock);
 	new->deleted = 0;
-- 
1.8.1.2

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