linux-kernel - Re: WARNING: at fs/dcache.c:1359 d_set_d_op [was: mmotm 2011-01-06-15-41 uploaded]

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Message-ID: <4D2ECC84.8050406@gmail.com>
Date:	Thu, 13 Jan 2011 10:57:24 +0100
From:	Jiri Slaby <jirislaby@...il.com>
To:	linux-kernel@...r.kernel.org
CC:	akpm@...ux-foundation.org, mm-commits@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	autofs@...ux.kernel.org, npiggin@...nel.dk
Subject: Re: WARNING: at fs/dcache.c:1359 d_set_d_op [was: mmotm 2011-01-06-15-41
 uploaded]

On 01/13/2011 10:52 AM, Jiri Slaby wrote:
> On 01/07/2011 12:41 AM, akpm@...ux-foundation.org wrote:
>> The mm-of-the-moment snapshot 2011-01-06-15-41 has been uploaded to
> 
> Hi, after some uptime and several suspend/resume cycles, I got:
> WARNING: at fs/dcache.c:1359 d_set_d_op+0x82/0xb0()
> Hardware name: To Be Filled By O.E.M.
> Modules linked in: dvb_usb_af9015 tda18271 af9013 dvb_usb dvb_core
> Pid: 3474, comm: automount Tainted: G        W   2.6.37-mm1_64+ #1344
> Call Trace:
>  [<ffffffff8106bd2a>] ? warn_slowpath_common+0x7a/0xb0
>  [<ffffffff8106bd75>] ? warn_slowpath_null+0x15/0x20
>  [<ffffffff81125a32>] ? d_set_d_op+0x82/0xb0
>  [<ffffffff8120d829>] ? autofs4_dir_mkdir+0x169/0x180
>  [<ffffffff8111caa8>] ? vfs_mkdir+0x78/0xa0
>  [<ffffffff811209e6>] ? sys_mkdirat+0xf6/0x110
>  [<ffffffff81120a13>] ? sys_mkdir+0x13/0x20
>  [<ffffffff81030dbb>] ? system_call_fastpath+0x16/0x1b

Note that even the second WARN was trigerred too:
WARNING: at fs/dcache.c:1365 d_set_d_op+0x9e/0xb0()
Hardware name: To Be Filled By O.E.M.
flags=00004000
Modules linked in: dvb_usb_af9015 tda18271 af9013 dvb_usb dvb_core
Pid: 3474, comm: automount Tainted: G        W   2.6.37-mm1_64+ #1344
Call Trace:
 [<ffffffff8106bd2a>] ? warn_slowpath_common+0x7a/0xb0
 [<ffffffff8106be01>] ? warn_slowpath_fmt+0x41/0x50
 [<ffffffff81125a4e>] ? d_set_d_op+0x9e/0xb0
 [<ffffffff8120d829>] ? autofs4_dir_mkdir+0x169/0x180
 [<ffffffff8111caa8>] ? vfs_mkdir+0x78/0xa0
 [<ffffffff811209e6>] ? sys_mkdirat+0xf6/0x110
 [<ffffffff81120a13>] ? sys_mkdir+0x13/0x20
 [<ffffffff81030dbb>] ? system_call_fastpath+0x16/0x1b

My d_set_d_op looks like:
        WARN_ON(dentry->d_op);
        if (WARN(dentry->d_flags & (DCACHE_OP_HASH      |
                                DCACHE_OP_COMPARE       |
                                DCACHE_OP_REVALIDATE    |
                                DCACHE_OP_REVALIDATE_RCU|
                                DCACHE_OP_DELETE),
                                "flags=%.8x", dentry->d_flags)) {
                dentry->d_flags &= ~(DCACHE_OP_HASH | DCACHE_OP_COMPARE |
                        DCACHE_OP_REVALIDATE | DCACHE_OP_REVALIDATE_RCU |
                        DCACHE_OP_DELETE);
        }

So DCACHE_OP_REVALIDATE remained set.

> I changed those BUG_ONs to WARN_ONs intentionally because I had problems
> with that previously -- I had to:
> dentry->d_flags &= ~(DCACHE_OP_HASH | DCACHE_OP_COMPARE |
>       DCACHE_OP_REVALIDATE | DCACHE_OP_REVALIDATE_RCU |
>       DCACHE_OP_DELETE);
> 
> in d_set_d_op to not oops when calling NULLish op->d_delete later.
> 
> 
> The "Tainted: G        W" is caused by:
> https://lkml.org/lkml/2011/1/10/63

regards,
-- 
js
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