linux-kernel - Re: [lkp-robot] [ipc] 296ba26b66: BUG:sleeping_function_called_from_invalid_context_at

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Date:   Wed, 22 Aug 2018 21:14:34 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     kernel test robot <rong.a.chen@...el.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Davidlohr Bueso <dbueso@...e.de>,
        Manfred Spraul <manfred@...orfullife.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Kees Cook <keescook@...omium.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...org,
        ltp@...ts.linux.it
Subject: Re: [lkp-robot] [ipc]  296ba26b66:
 BUG:sleeping_function_called_from_invalid_context_at_mm/memory.c

On Thu, 23 Aug 2018, kernel test robot wrote:

>FYI, we noticed the following commit (built with gcc-7):
>
>commit: 296ba26b6681b6e07ed419b3004647167cb17f61 ("ipc: drop ipc_lock()")
>https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master

I suspect this is because that commit forgot to set EIDRM for the
!ipc_valid_object() case. So the callers check IS_ERR(shm_lock()),
which won't fail the op as it did before the commit.

diff --git a/ipc/shm.c b/ipc/shm.c
index b0eb3757ab89..4cd402e4cfeb 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -199,6 +199,7 @@ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 	}
 
 	ipc_unlock_object(ipcp);
+	ipcp = ERR_PTR(-EIDRM);
 err:
 	rcu_read_unlock();
 	/*