From: Shyam Prasad N <nspmangalore@gmail.com>
To: Paulo Alcantara <pc@manguebit.com>
Cc: smfrench@gmail.com, bharathsm.hsk@gmail.com,
linux-cifs@vger.kernel.org,
Shyam Prasad N <sprasad@microsoft.com>
Subject: Re: [PATCH 13/14] cifs: display the endpoint IP details in DebugData
Date: Sat, 4 Nov 2023 13:14:46 +0530 [thread overview]
Message-ID: <CANT5p=pna6WxpSy5fXwsDGRJFRVpRaVCzp8uLFV4keOXcdvv5A@mail.gmail.com> (raw)
In-Reply-To: <d1c99946663662e7160bf1ed0a6b2dc6.pc@manguebit.com>
On Wed, Nov 1, 2023 at 7:42 PM Paulo Alcantara <pc@manguebit.com> wrote:
>
> Paulo Alcantara <pc@manguebit.com> writes:
>
> >> @@ -515,7 +573,18 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
> >> seq_printf(m, "\n\n\tExtra Channels: %zu ",
> >> ses->chan_count-1);
> >> for (j = 1; j < ses->chan_count; j++) {
> >> + /*
> >> + * kernel_getsockname can block inside
> >> + * cifs_dump_channel. so drop the lock first
> >> + */
> >> + server->srv_count++;
> >> + spin_unlock(&cifs_tcp_ses_lock);
> >> +
> >> cifs_dump_channel(m, j, &ses->chans[j]);
> >> +
> >> + cifs_put_tcp_session(server, 0);
> >> + spin_lock(&cifs_tcp_ses_lock);
> >
> > Here you are re-acquiring @cifs_tcp_ses_lock spinlock under
> > @ses->chan_lock, which will introduce deadlocks in threads calling
> > cifs_match_super(), cifs_signal_cifsd_for_reconnect(),
> > cifs_mark_tcp_ses_conns_for_reconnect(), cifs_find_smb_ses(), ...
>
Good points.
I'm just wondering why I'm unable to repro the same though.
I have lockdep enabled on my kernel too. But the same steps do not
throw this warning.
> A simple reproducer
>
> $ mount.cifs //srv/share /mnt -o ...,multichannel
> $ cat /proc/fs/cifs/DebugData
>
> [ 1293.512572] BUG: sleeping function called from invalid context at net/core/sock.c:3507
> [ 1293.513915] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1068, name: cat
> [ 1293.515381] preempt_count: 1, expected: 0
> [ 1293.516321] RCU nest depth: 0, expected: 0
> [ 1293.517294] 3 locks held by cat/1068:
> [ 1293.518165] #0: ffff88800818fc48 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x59/0x470
> [ 1293.519383] #1: ffff88800aed2b28 (&ret_buf->chan_lock){+.+.}-{2:2}, at: cifs_debug_data_proc_show+0x555/0xee0 [cifs]
> [ 1293.520865] #2: ffff888011c9a540 (sk_lock-AF_INET-CIFS){+.+.}-{0:0}, at: inet_getname+0x29/0xa0
> [ 1293.522098] CPU: 3 PID: 1068 Comm: cat Not tainted 6.6.0-rc7 #2
> [ 1293.522901] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
> [ 1293.524368] Call Trace:
> [ 1293.524711] <TASK>
> [ 1293.525015] dump_stack_lvl+0x64/0x80
> [ 1293.525519] __might_resched+0x173/0x280
> [ 1293.526059] lock_sock_nested+0x43/0x80
> [ 1293.526578] ? inet_getname+0x29/0xa0
> [ 1293.527097] inet_getname+0x29/0xa0
> [ 1293.527584] cifs_debug_data_proc_show+0xcf9/0xee0 [cifs]
> [ 1293.528360] seq_read_iter+0x118/0x470
> [ 1293.528877] proc_reg_read_iter+0x53/0x90
> [ 1293.529419] ? srso_alias_return_thunk+0x5/0x7f
> [ 1293.530037] vfs_read+0x201/0x350
> [ 1293.530507] ksys_read+0x75/0x100
> [ 1293.530968] do_syscall_64+0x3f/0x90
> [ 1293.531461] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 1293.532138] RIP: 0033:0x7f71d767e381
> [ 1293.532630] Code: ff ff eb c3 e8 0e ea 01 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 90 90 80 3d a5 f6 0e 00 00 74 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 c3 66 0f 1f 44 00 00 48 83 ec 28 48 89 54
> [ 1293.535095] RSP: 002b:00007ffc312d65a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [ 1293.536106] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f71d767e381
> [ 1293.537056] RDX: 0000000000020000 RSI: 00007f71d74f8000 RDI: 0000000000000003
> [ 1293.538003] RBP: 0000000000020000 R08: 00000000ffffffff R09: 0000000000000000
> [ 1293.538957] R10: 0000000000000022 R11: 0000000000000246 R12: 00007f71d74f8000
> [ 1293.539908] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000020000
> [ 1293.540877] </TASK>
> [ 1293.541233]
> [ 1293.541449] ======================================================
> [ 1293.542270] WARNING: possible circular locking dependency detected
> [ 1293.543098] 6.6.0-rc7 #2 Tainted: G W
> [ 1293.543782] ------------------------------------------------------
> [ 1293.544606] cat/1068 is trying to acquire lock:
> [ 1293.545214] ffffffffc015b5f8 (&cifs_tcp_ses_lock){+.+.}-{2:2}, at: cifs_put_tcp_session+0x1c/0x180 [cifs]
> [ 1293.546516]
> [ 1293.546516] but task is already holding lock:
> [ 1293.547292] ffff88800aed2b28 (&ret_buf->chan_lock){+.+.}-{2:2}, at: cifs_debug_data_proc_show+0x555/0xee0 [cifs]
> [ 1293.548454]
> [ 1293.548454] which lock already depends on the new lock.
> [ 1293.548454]
> [ 1293.549350]
> [ 1293.549350] the existing dependency chain (in reverse order) is:
> [ 1293.550183]
> [ 1293.550183] -> #1 (&ret_buf->chan_lock){+.+.}-{2:2}:
> [ 1293.550899] _raw_spin_lock+0x34/0x80
> [ 1293.551401] cifs_debug_data_proc_show+0x555/0xee0 [cifs]
> [ 1293.552082] seq_read_iter+0x118/0x470
> [ 1293.552556] proc_reg_read_iter+0x53/0x90
> [ 1293.553054] vfs_read+0x201/0x350
> [ 1293.553490] ksys_read+0x75/0x100
> [ 1293.553925] do_syscall_64+0x3f/0x90
> [ 1293.554389] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 1293.555004]
> [ 1293.555004] -> #0 (&cifs_tcp_ses_lock){+.+.}-{2:2}:
> [ 1293.555709] __lock_acquire+0x1521/0x2660
> [ 1293.556218] lock_acquire+0xbf/0x2b0
> [ 1293.556680] _raw_spin_lock+0x34/0x80
> [ 1293.557148] cifs_put_tcp_session+0x1c/0x180 [cifs]
> [ 1293.557773] cifs_debug_data_proc_show+0xd15/0xee0 [cifs]
> [ 1293.558463] seq_read_iter+0x118/0x470
> [ 1293.558945] proc_reg_read_iter+0x53/0x90
> [ 1293.559450] vfs_read+0x201/0x350
> [ 1293.559882] ksys_read+0x75/0x100
> [ 1293.560317] do_syscall_64+0x3f/0x90
> [ 1293.560773] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 1293.561390]
> [ 1293.561390] other info that might help us debug this:
> [ 1293.561390]
> [ 1293.562267] Possible unsafe locking scenario:
> [ 1293.562267]
> [ 1293.562927] CPU0 CPU1
> [ 1293.563394] ---- ----
> [ 1293.563754] lock(&ret_buf->chan_lock);
> [ 1293.564068] lock(&cifs_tcp_ses_lock);
> [ 1293.564573] lock(&ret_buf->chan_lock);
> [ 1293.565077] lock(&cifs_tcp_ses_lock);
> [ 1293.565387]
> [ 1293.565387] *** DEADLOCK ***
> [ 1293.565387]
> [ 1293.565852] 2 locks held by cat/1068:
> [ 1293.566147] #0: ffff88800818fc48 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x59/0x470
> [ 1293.566767] #1: ffff88800aed2b28 (&ret_buf->chan_lock){+.+.}-{2:2}, at: cifs_debug_data_proc_show+0x555/0xee0 [cifs]
> [ 1293.567611]
> [ 1293.567611] stack backtrace:
> [ 1293.567954] CPU: 3 PID: 1068 Comm: cat Tainted: G W 6.6.0-rc7 #2
> [ 1293.568536] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
> [ 1293.569387] Call Trace:
> [ 1293.569585] <TASK>
> [ 1293.569755] dump_stack_lvl+0x4a/0x80
> [ 1293.570047] check_noncircular+0x14e/0x170
> [ 1293.570373] ? save_trace+0x3e/0x390
> [ 1293.570659] __lock_acquire+0x1521/0x2660
> [ 1293.570982] lock_acquire+0xbf/0x2b0
> [ 1293.571268] ? cifs_put_tcp_session+0x1c/0x180 [cifs]
> [ 1293.571687] _raw_spin_lock+0x34/0x80
> [ 1293.571977] ? cifs_put_tcp_session+0x1c/0x180 [cifs]
> [ 1293.572394] cifs_put_tcp_session+0x1c/0x180 [cifs]
> [ 1293.572795] cifs_debug_data_proc_show+0xd15/0xee0 [cifs]
> [ 1293.573241] seq_read_iter+0x118/0x470
> [ 1293.573546] proc_reg_read_iter+0x53/0x90
> [ 1293.573861] ? srso_alias_return_thunk+0x5/0x7f
> [ 1293.574218] vfs_read+0x201/0x350
> [ 1293.574489] ksys_read+0x75/0x100
> [ 1293.574752] do_syscall_64+0x3f/0x90
> [ 1293.575030] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 1293.575428] RIP: 0033:0x7f71d767e381
> [ 1293.575716] Code: ff ff eb c3 e8 0e ea 01 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 90 90 80 3d a5 f6 0e 00 00 74 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 c3 66 0f 1f 44 00 00 48 83 ec 28 48 89 54
> [ 1293.577151] RSP: 002b:00007ffc312d65a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [ 1293.577736] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f71d767e381
> [ 1293.578286] RDX: 0000000000020000 RSI: 00007f71d74f8000 RDI: 0000000000000003
> [ 1293.578839] RBP: 0000000000020000 R08: 00000000ffffffff R09: 0000000000000000
> [ 1293.579391] R10: 0000000000000022 R11: 0000000000000246 R12: 00007f71d74f8000
> [ 1293.579951] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000020000
> [ 1293.580511] </TASK>
--
Regards,
Shyam
next prev parent reply other threads:[~2023-11-04 7:45 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-30 11:00 [PATCH 01/14] cifs: print server capabilities in DebugData nspmangalore
2023-10-30 11:00 ` [PATCH 02/14] cifs: add xid to query server interface call nspmangalore
2023-10-31 5:35 ` Bharath SM
2023-10-30 11:00 ` [PATCH 03/14] cifs: reconnect helper should set reconnect for the right channel nspmangalore
2023-10-31 15:27 ` Paulo Alcantara
2023-10-31 18:29 ` Steve French
2023-10-30 11:00 ` [PATCH 04/14] cifs: do not reset chan_max if multichannel is not supported at mount nspmangalore
2023-11-01 2:57 ` Steve French
2023-11-01 3:14 ` Steve French
2023-10-30 11:00 ` [PATCH 05/14] cifs: force interface update before a fresh session setup nspmangalore
2023-11-01 3:14 ` Steve French
2023-10-30 11:00 ` [PATCH 06/14] cifs: handle cases where a channel is closed nspmangalore
2023-11-01 3:09 ` Steve French
2023-11-02 12:26 ` Shyam Prasad N
2023-10-30 11:00 ` [PATCH 07/14] cifs: distribute channels across interfaces based on speed nspmangalore
2023-10-30 11:00 ` [PATCH 08/14] cifs: account for primary channel in the interface list nspmangalore
2023-11-08 15:44 ` Paulo Alcantara
2023-11-08 18:16 ` Steve French
2023-11-08 19:03 ` Paulo Alcantara
2023-10-30 11:00 ` [PATCH 09/14] cifs: add a back pointer to cifs_sb from tcon nspmangalore
2023-11-01 3:30 ` Steve French
2023-11-03 21:03 ` Paulo Alcantara
2023-11-06 16:12 ` Shyam Prasad N
2023-11-06 17:04 ` Shyam Prasad N
[not found] ` <CAH2r5msQLTcdiHBrOKd+q6LPPHW_Jj3QbpFZyZ48CJbrtDqC5w@mail.gmail.com>
[not found] ` <CAH2r5mt4hC5x2w2D46y13j_OtjkJk9_ZaeGXbb7YKukffBk2LQ@mail.gmail.com>
2023-11-06 19:36 ` Fwd: " Steve French
2023-11-08 15:24 ` Paulo Alcantara
2023-11-08 16:11 ` Steve French
2023-10-30 11:00 ` [PATCH 10/14] cifs: reconnect work should have reference on server struct nspmangalore
2023-11-16 17:10 ` Paulo Alcantara
[not found] ` <CAH2r5mtDeP323Z8=9WjCCYVVb9B2AmO5Q4PDtcMz8wxVUCVRBA@mail.gmail.com>
2023-11-16 19:35 ` Paulo Alcantara
2023-10-30 11:00 ` [PATCH 11/14] cifs: handle when server starts supporting multichannel nspmangalore
2023-11-01 3:30 ` Steve French
2023-11-01 15:52 ` Paulo Alcantara
2023-11-04 7:50 ` Shyam Prasad N
2023-11-02 20:28 ` Paulo Alcantara
2023-11-03 0:43 ` Steve French
2023-11-03 20:32 ` Paulo Alcantara
[not found] ` <notmuch-sha1-c3bfa7f4ae0bb24c5ee7cfddb408c2fbeca5d8f7>
2023-11-08 16:02 ` Paulo Alcantara
2023-11-08 19:25 ` Steve French
2023-11-08 19:31 ` Paulo Alcantara
2023-10-30 11:00 ` [PATCH 12/14] cifs: handle when server stops " nspmangalore
2023-11-08 16:35 ` Paulo Alcantara
[not found] ` <notmuch-sha1-9ed0289358ca5c90903408ad9c0ac0310afee598>
2023-11-08 19:13 ` Paulo Alcantara
2023-11-08 19:41 ` Paulo Alcantara
2023-11-09 11:44 ` Shyam Prasad N
2023-11-09 13:28 ` Paulo Alcantara
2023-11-09 13:49 ` Shyam Prasad N
2023-11-10 4:09 ` Shyam Prasad N
2023-11-11 17:23 ` Paulo Alcantara
2023-11-12 18:52 ` Steve French
[not found] ` <CAH2r5mvG3zLBxknPOuaz9=GarZO6n6bhcduiZHHfiqVYZYJiVQ@mail.gmail.com>
2023-11-12 19:32 ` Paulo Alcantara
2023-10-30 11:00 ` [PATCH 13/14] cifs: display the endpoint IP details in DebugData nspmangalore
2023-10-31 15:18 ` Paulo Alcantara
[not found] ` <notmuch-sha1-260ef7fe7af7face0e1486229c0fda5149fe14e2>
2023-11-01 14:12 ` Paulo Alcantara
2023-11-01 14:19 ` Steve French
2023-11-04 7:44 ` Shyam Prasad N [this message]
2023-11-04 19:00 ` Paulo Alcantara
2023-10-30 12:34 ` [PATCH 01/14] cifs: print server capabilities " Bharath SM
2023-10-30 12:40 ` Shyam Prasad N
2023-10-30 12:51 ` Shyam Prasad N
2023-10-30 14:54 ` Steve French
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