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Message-ID: <20150402041135.GA22514@wfg-t540p.sh.intel.com>
Date: Thu, 2 Apr 2015 12:11:35 +0800
From: Fengguang Wu <fengguang.wu@...el.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: LKP <lkp@...org>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [rhashtable] [ INFO: suspicious RCU usage. ]
On Thu, Apr 02, 2015 at 11:58:10AM +0800, Herbert Xu wrote:
> On Thu, Apr 02, 2015 at 08:52:11AM +0800, Fengguang Wu wrote:
> > Hi Herbert,
> >
> > 0day kernel testing robot got the below dmesg and the first bad commit is
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> >
> > commit ccd57b1bd32460d27bbb9c599e795628a3c66983
> > Author: Herbert Xu <herbert@...dor.apana.org.au>
> > AuthorDate: Tue Mar 24 00:50:28 2015 +1100
> > Commit: David S. Miller <davem@...emloft.net>
> > CommitDate: Mon Mar 23 22:07:52 2015 -0400
> >
> > rhashtable: Add immediate rehash during insertion
> >
> > This patch reintroduces immediate rehash during insertion. If
> > we find during insertion that the table is full or the chain
> > length exceeds a set limit (currently 16 but may be disabled
> > with insecure_elasticity) then we will force an immediate rehash.
> > The rehash will contain an expansion if the table utilisation
> > exceeds 75%.
> >
> > If this rehash fails then the insertion will fail. Otherwise the
> > insertion will be reattempted in the new hash table.
> >
> > Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
> > Acked-by: Thomas Graf <tgraf@...g.ch>
> > Signed-off-by: David S. Miller <davem@...emloft.net>
> >
> > [ 0.552992] Adding 2048 keys
> > [ 0.553792]
> > [ 0.554400] ===============================
> > [ 0.555285] [ INFO: suspicious RCU usage. ]
> > [ 0.556176] 4.0.0-rc4-01225-gccd57b1 #171 Not tainted
> > [ 0.557156] -------------------------------
> > [ 0.558044] lib/rhashtable.c:400 suspicious rcu_dereference_check() usage!
>
> This should have been fixed by
>
> 58be8a583d8d316448bafa5926414cfb83c02dec.
>
> Can you check whether this commit was in your tested tree?
Yes it is contained in next-20150401 which is bad:
# extra tests on tree/branch next/master
git bisect bad e954104e2b634b42811dad8d502cbf240f206df2 # 21:22 0- 60 Add linux-next specific files for 20150401
The dmesg there is
[ 1.149409] test_firmware: interface ready
[ 1.150293] Running resizable hashtable tests...
[ 1.151209] Adding 2048 keys
[ 1.152069] ------------[ cut here ]------------
[ 1.152978] WARNING: CPU: 0 PID: 1 at lib/rhashtable.c:409 rhashtable_insert_rehash+0x9d/0x1d0()
[ 1.154802] Modules linked in:
[ 1.155628] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.0.0-rc6-next-20150401 #1
[ 1.157185] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 1.159019] ffffffff81d1ce18 ffff880010dc3d18 ffffffff8189b1c3 0000000000000000
[ 1.160865] 0000000000000000 ffff880010dc3d58 ffffffff810b12aa ffff880010dc3d38
[ 1.162716] ffffffff8323a500 0000000000000010 ffff88000beda780 0000000000000001
[ 1.164558] Call Trace:
[ 1.165249] [<ffffffff8189b1c3>] dump_stack+0x4c/0x65
[ 1.166220] [<ffffffff810b12aa>] warn_slowpath_common+0x8a/0xc0
[ 1.167267] [<ffffffff810b139a>] warn_slowpath_null+0x1a/0x20
[ 1.168317] [<ffffffff81443b3d>] rhashtable_insert_rehash+0x9d/0x1d0
[ 1.169415] [<ffffffff8225456e>] test_rht_init+0x310/0x12ba
[ 1.170425] [<ffffffff810002c0>] ? do_one_initcall+0x80/0x200
[ 1.171466] [<ffffffff8225425e>] ? test_firmware_init+0x79/0x79
[ 1.172524] [<ffffffff810002d0>] do_one_initcall+0x90/0x200
[ 1.173552] [<ffffffff8221e200>] kernel_init_freeable+0x22d/0x2b5
[ 1.174625] [<ffffffff81894f60>] ? rest_init+0x140/0x140
[ 1.175617] [<ffffffff81894f6e>] kernel_init+0xe/0xf0
[ 1.176572] [<ffffffff818a6c43>] ret_from_fork+0x53/0x90
[ 1.177576] [<ffffffff81894f60>] ? rest_init+0x140/0x140
[ 1.178570] ---[ end trace 0ba1594e5c63400d ]---
[ 1.179477]
[ 1.180071] ===============================
[ 1.180911] [ INFO: suspicious RCU usage. ]
[ 1.181768] 4.0.0-rc6-next-20150401 #1 Tainted: G W
[ 1.182818] -------------------------------
[ 1.183688] lib/test_rhashtable.c:176 suspicious rcu_dereference_check() usage!
[ 1.185387]
[ 1.185387] other info that might help us debug this:
[ 1.185387]
[ 1.187369]
[ 1.187369] rcu_scheduler_active = 1, debug_locks = 0
[ 1.188835] no locks held by swapper/0/1.
[ 1.189676]
[ 1.189676] stack backtrace:
[ 1.190917] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.0.0-rc6-next-20150401 #1
[ 1.192595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 1.194428] 0000000000000001 ffff880010dc3d78 ffffffff8189b1c3 0000000000000011
[ 1.196272] ffff880010db8000 ffff880010dc3da8 ffffffff81102d17 ffff880010f93d20
[ 1.207362] ffff88000c6530f0 0000000000000004 ffff88000beda6c0 ffff880010dc3e18
[ 1.209218] Call Trace:
[ 1.209897] [<ffffffff8189b1c3>] dump_stack+0x4c/0x65
[ 1.210867] [<ffffffff81102d17>] lockdep_rcu_suspicious+0xe7/0x120
[ 1.211948] [<ffffffff822553c6>] test_rht_init+0x1168/0x12ba
[ 1.212968] [<ffffffff810002c0>] ? do_one_initcall+0x80/0x200
[ 1.214007] [<ffffffff8225425e>] ? test_firmware_init+0x79/0x79
[ 1.215060] [<ffffffff810002d0>] do_one_initcall+0x90/0x200
[ 1.216075] [<ffffffff8221e200>] kernel_init_freeable+0x22d/0x2b5
[ 1.217140] [<ffffffff81894f60>] ? rest_init+0x140/0x140
[ 1.218130] [<ffffffff81894f6e>] kernel_init+0xe/0xf0
[ 1.219094] [<ffffffff818a6c43>] ret_from_fork+0x53/0x90
[ 1.220066] [<ffffffff81894f60>] ? rest_init+0x140/0x140
[ 1.221075] glob: 64 self-tests passed, 0 failed
Thanks,
Fengguang
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