* Deadlock between bind and splice
@ 2015-11-06 12:58 Dmitry Vyukov
2015-11-06 15:42 ` Eric Dumazet
2015-11-10 2:31 ` Al Viro
0 siblings, 2 replies; 7+ messages in thread
From: Dmitry Vyukov @ 2015-11-06 12:58 UTC (permalink / raw)
To: netdev, David Miller, Eric Dumazet, Kostya Serebryany,
Alexander Potapenko, Sasha Levin, syzkaller, Alexey Kuznetsov
Hello,
I am on revision d1e41ff11941784f469f17795a4d9425c2eb4b7a (Nov 5) and
seeing the following lockdep reports. I don't have exact reproducer
program as it is caused by several independent programs (state
accumulated in kernel across invocations); if the report is not enough
I can try to cook a reproducer.
Thanks.
[ INFO: possible circular locking dependency detected ]
4.3.0+ #30 Not tainted
-------------------------------------------------------
a.out/9972 is trying to acquire lock:
(&pipe->mutex/1){+.+.+.}, at: [< inline >] pipe_lock_nested
fs/pipe.c:59
(&pipe->mutex/1){+.+.+.}, at: [<ffffffff814d6e46>]
pipe_lock+0x56/0x70 fs/pipe.c:67
but task is already holding lock:
(sb_writers#5){.+.+.+}, at: [<ffffffff814c77ec>]
__sb_start_write+0xec/0x130 fs/super.c:1198
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (sb_writers#5){.+.+.+}:
[<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
kernel/locking/lockdep.c:3585
[<ffffffff811e434c>] percpu_down_read+0x3c/0xa0
kernel/locking/percpu-rwsem.c:73
[<ffffffff814c77ec>] __sb_start_write+0xec/0x130 fs/super.c:1198
[< inline >] sb_start_write include/linux/fs.h:1449
[<ffffffff81526f4f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386
[<ffffffff814f43f6>] filename_create+0x106/0x450 fs/namei.c:3425
[<ffffffff814f4773>] kern_path_create+0x33/0x40 fs/namei.c:3471
[< inline >] unix_mknod net/unix/af_unix.c:849
[<ffffffff82acb27b>] unix_bind+0x41b/0xa10 net/unix/af_unix.c:917
[<ffffffff827636da>] SYSC_bind+0x1ea/0x250 net/socket.c:1383
[<ffffffff82766164>] SyS_bind+0x24/0x30 net/socket.c:1369
[<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
arch/x86/entry/entry_64.S:187
-> #1 (&u->readlock){+.+.+.}:
[<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
kernel/locking/lockdep.c:3585
[< inline >] __mutex_lock_common kernel/locking/mutex.c:518
[<ffffffff82f196c9>] mutex_lock_interruptible_nested+0xa9/0xa30
kernel/locking/mutex.c:647
[<ffffffff82ac32bc>] unix_stream_sendpage+0x23c/0x700
net/unix/af_unix.c:1768
[<ffffffff82761690>] kernel_sendpage+0x90/0xe0 net/socket.c:3278
[<ffffffff82761785>] sock_sendpage+0xa5/0xd0 net/socket.c:765
[<ffffffff8155668a>] pipe_to_sendpage+0x26a/0x320 fs/splice.c:720
[< inline >] splice_from_pipe_feed fs/splice.c:772
[<ffffffff815579a8>] __splice_from_pipe+0x268/0x740 fs/splice.c:889
[<ffffffff8155c2f7>] splice_from_pipe+0xf7/0x140 fs/splice.c:924
[<ffffffff8155c380>] generic_splice_sendpage+0x40/0x50 fs/splice.c:1097
[< inline >] do_splice_from fs/splice.c:1116
[< inline >] do_splice fs/splice.c:1392
[< inline >] SYSC_splice fs/splice.c:1695
[<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
[<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
arch/x86/entry/entry_64.S:187
-> #0 (&pipe->mutex/1){+.+.+.}:
[< inline >] check_prev_add kernel/locking/lockdep.c:1853
[< inline >] check_prevs_add kernel/locking/lockdep.c:1958
[< inline >] validate_chain kernel/locking/lockdep.c:2144
[<ffffffff811f3769>] __lock_acquire+0x36d9/0x40e0
kernel/locking/lockdep.c:3206
[<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
kernel/locking/lockdep.c:3585
[< inline >] __mutex_lock_common kernel/locking/mutex.c:518
[<ffffffff82f18dcc>] mutex_lock_nested+0x9c/0x8f0
kernel/locking/mutex.c:618
[< inline >] pipe_lock_nested fs/pipe.c:59
[<ffffffff814d6e46>] pipe_lock+0x56/0x70 fs/pipe.c:67
[<ffffffff815581c9>] iter_file_splice_write+0x199/0xb20 fs/splice.c:962
[< inline >] do_splice_from fs/splice.c:1116
[< inline >] do_splice fs/splice.c:1392
[< inline >] SYSC_splice fs/splice.c:1695
[<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
[<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
arch/x86/entry/entry_64.S:187
other info that might help us debug this:
Chain exists of:
&pipe->mutex/1 --> &u->readlock --> sb_writers#5
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#5);
lock(&u->readlock);
lock(sb_writers#5);
lock(&pipe->mutex/1);
*** DEADLOCK ***
1 lock held by a.out/9972:
#0: (sb_writers#5){.+.+.+}, at: [<ffffffff814c77ec>]
__sb_start_write+0xec/0x130 fs/super.c:1198
stack backtrace:
CPU: 1 PID: 9972 Comm: a.out Not tainted 4.3.0+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
00000000ffffffff ffff88003d777938 ffffffff81aad406 ffffffff846046a0
ffffffff84606860 ffffffff846086c0 ffff88003d777980 ffffffff811ec511
ffff88003d777a80 000000003cf79640 ffff88003cf79df0 ffff88003cf79e12
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff81aad406>] dump_stack+0x68/0x92 lib/dump_stack.c:50
[<ffffffff811ec511>] print_circular_bug+0x2d1/0x390
kernel/locking/lockdep.c:1226
[< inline >] check_prev_add kernel/locking/lockdep.c:1853
[< inline >] check_prevs_add kernel/locking/lockdep.c:1958
[< inline >] validate_chain kernel/locking/lockdep.c:2144
[<ffffffff811f3769>] __lock_acquire+0x36d9/0x40e0 kernel/locking/lockdep.c:3206
[<ffffffff811f655d>] lock_acquire+0x16d/0x2f0 kernel/locking/lockdep.c:3585
[< inline >] __mutex_lock_common kernel/locking/mutex.c:518
[<ffffffff82f18dcc>] mutex_lock_nested+0x9c/0x8f0 kernel/locking/mutex.c:618
[< inline >] pipe_lock_nested fs/pipe.c:59
[<ffffffff814d6e46>] pipe_lock+0x56/0x70 fs/pipe.c:67
[<ffffffff815581c9>] iter_file_splice_write+0x199/0xb20 fs/splice.c:962
[< inline >] do_splice_from fs/splice.c:1116
[< inline >] do_splice fs/splice.c:1392
[< inline >] SYSC_splice fs/splice.c:1695
[<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
[<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
arch/x86/entry/entry_64.S:187
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-06 12:58 Deadlock between bind and splice Dmitry Vyukov
@ 2015-11-06 15:42 ` Eric Dumazet
2015-11-10 2:38 ` Al Viro
2015-11-10 2:31 ` Al Viro
1 sibling, 1 reply; 7+ messages in thread
From: Eric Dumazet @ 2015-11-06 15:42 UTC (permalink / raw)
To: Dmitry Vyukov, Al Viro, linux-fsdevel, linux-kernel
Cc: netdev, David Miller, Eric Dumazet, Kostya Serebryany,
Alexander Potapenko, Sasha Levin, syzkaller, Alexey Kuznetsov
On Fri, 2015-11-06 at 13:58 +0100, Dmitry Vyukov wrote:
> Hello,
>
> I am on revision d1e41ff11941784f469f17795a4d9425c2eb4b7a (Nov 5) and
> seeing the following lockdep reports. I don't have exact reproducer
> program as it is caused by several independent programs (state
> accumulated in kernel across invocations); if the report is not enough
> I can try to cook a reproducer.
>
> Thanks.
>
> [ INFO: possible circular locking dependency detected ]
> 4.3.0+ #30 Not tainted
> -------------------------------------------------------
> a.out/9972 is trying to acquire lock:
> (&pipe->mutex/1){+.+.+.}, at: [< inline >] pipe_lock_nested
> fs/pipe.c:59
> (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814d6e46>]
> pipe_lock+0x56/0x70 fs/pipe.c:67
>
> but task is already holding lock:
> (sb_writers#5){.+.+.+}, at: [<ffffffff814c77ec>]
> __sb_start_write+0xec/0x130 fs/super.c:1198
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #2 (sb_writers#5){.+.+.+}:
> [<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
> kernel/locking/lockdep.c:3585
> [<ffffffff811e434c>] percpu_down_read+0x3c/0xa0
> kernel/locking/percpu-rwsem.c:73
> [<ffffffff814c77ec>] __sb_start_write+0xec/0x130 fs/super.c:1198
> [< inline >] sb_start_write include/linux/fs.h:1449
> [<ffffffff81526f4f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386
> [<ffffffff814f43f6>] filename_create+0x106/0x450 fs/namei.c:3425
> [<ffffffff814f4773>] kern_path_create+0x33/0x40 fs/namei.c:3471
> [< inline >] unix_mknod net/unix/af_unix.c:849
> [<ffffffff82acb27b>] unix_bind+0x41b/0xa10 net/unix/af_unix.c:917
> [<ffffffff827636da>] SYSC_bind+0x1ea/0x250 net/socket.c:1383
> [<ffffffff82766164>] SyS_bind+0x24/0x30 net/socket.c:1369
> [<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
> arch/x86/entry/entry_64.S:187
>
> -> #1 (&u->readlock){+.+.+.}:
> [<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
> kernel/locking/lockdep.c:3585
> [< inline >] __mutex_lock_common kernel/locking/mutex.c:518
> [<ffffffff82f196c9>] mutex_lock_interruptible_nested+0xa9/0xa30
> kernel/locking/mutex.c:647
> [<ffffffff82ac32bc>] unix_stream_sendpage+0x23c/0x700
> net/unix/af_unix.c:1768
> [<ffffffff82761690>] kernel_sendpage+0x90/0xe0 net/socket.c:3278
> [<ffffffff82761785>] sock_sendpage+0xa5/0xd0 net/socket.c:765
> [<ffffffff8155668a>] pipe_to_sendpage+0x26a/0x320 fs/splice.c:720
> [< inline >] splice_from_pipe_feed fs/splice.c:772
> [<ffffffff815579a8>] __splice_from_pipe+0x268/0x740 fs/splice.c:889
> [<ffffffff8155c2f7>] splice_from_pipe+0xf7/0x140 fs/splice.c:924
> [<ffffffff8155c380>] generic_splice_sendpage+0x40/0x50 fs/splice.c:1097
> [< inline >] do_splice_from fs/splice.c:1116
> [< inline >] do_splice fs/splice.c:1392
> [< inline >] SYSC_splice fs/splice.c:1695
> [<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
> [<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
> arch/x86/entry/entry_64.S:187
>
> -> #0 (&pipe->mutex/1){+.+.+.}:
> [< inline >] check_prev_add kernel/locking/lockdep.c:1853
> [< inline >] check_prevs_add kernel/locking/lockdep.c:1958
> [< inline >] validate_chain kernel/locking/lockdep.c:2144
> [<ffffffff811f3769>] __lock_acquire+0x36d9/0x40e0
> kernel/locking/lockdep.c:3206
> [<ffffffff811f655d>] lock_acquire+0x16d/0x2f0
> kernel/locking/lockdep.c:3585
> [< inline >] __mutex_lock_common kernel/locking/mutex.c:518
> [<ffffffff82f18dcc>] mutex_lock_nested+0x9c/0x8f0
> kernel/locking/mutex.c:618
> [< inline >] pipe_lock_nested fs/pipe.c:59
> [<ffffffff814d6e46>] pipe_lock+0x56/0x70 fs/pipe.c:67
> [<ffffffff815581c9>] iter_file_splice_write+0x199/0xb20 fs/splice.c:962
> [< inline >] do_splice_from fs/splice.c:1116
> [< inline >] do_splice fs/splice.c:1392
> [< inline >] SYSC_splice fs/splice.c:1695
> [<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
> [<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
> arch/x86/entry/entry_64.S:187
>
> other info that might help us debug this:
>
> Chain exists of:
> &pipe->mutex/1 --> &u->readlock --> sb_writers#5
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(sb_writers#5);
> lock(&u->readlock);
> lock(sb_writers#5);
> lock(&pipe->mutex/1);
>
> *** DEADLOCK ***
>
> 1 lock held by a.out/9972:
> #0: (sb_writers#5){.+.+.+}, at: [<ffffffff814c77ec>]
> __sb_start_write+0xec/0x130 fs/super.c:1198
>
> stack backtrace:
> CPU: 1 PID: 9972 Comm: a.out Not tainted 4.3.0+ #30
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> 00000000ffffffff ffff88003d777938 ffffffff81aad406 ffffffff846046a0
> ffffffff84606860 ffffffff846086c0 ffff88003d777980 ffffffff811ec511
> ffff88003d777a80 000000003cf79640 ffff88003cf79df0 ffff88003cf79e12
> Call Trace:
> [< inline >] __dump_stack lib/dump_stack.c:15
> [<ffffffff81aad406>] dump_stack+0x68/0x92 lib/dump_stack.c:50
> [<ffffffff811ec511>] print_circular_bug+0x2d1/0x390
> kernel/locking/lockdep.c:1226
> [< inline >] check_prev_add kernel/locking/lockdep.c:1853
> [< inline >] check_prevs_add kernel/locking/lockdep.c:1958
> [< inline >] validate_chain kernel/locking/lockdep.c:2144
> [<ffffffff811f3769>] __lock_acquire+0x36d9/0x40e0 kernel/locking/lockdep.c:3206
> [<ffffffff811f655d>] lock_acquire+0x16d/0x2f0 kernel/locking/lockdep.c:3585
> [< inline >] __mutex_lock_common kernel/locking/mutex.c:518
> [<ffffffff82f18dcc>] mutex_lock_nested+0x9c/0x8f0 kernel/locking/mutex.c:618
> [< inline >] pipe_lock_nested fs/pipe.c:59
> [<ffffffff814d6e46>] pipe_lock+0x56/0x70 fs/pipe.c:67
> [<ffffffff815581c9>] iter_file_splice_write+0x199/0xb20 fs/splice.c:962
> [< inline >] do_splice_from fs/splice.c:1116
> [< inline >] do_splice fs/splice.c:1392
> [< inline >] SYSC_splice fs/splice.c:1695
> [<ffffffff8155d005>] SyS_splice+0x845/0x17c0 fs/splice.c:1678
> [<ffffffff82f21951>] entry_SYSCALL_64_fastpath+0x31/0x9a
> arch/x86/entry/entry_64.S:187
> --
Thank you for this report.
pipe is part of fs, not net ;)
CC Al Viro.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-06 12:58 Deadlock between bind and splice Dmitry Vyukov
2015-11-06 15:42 ` Eric Dumazet
@ 2015-11-10 2:31 ` Al Viro
1 sibling, 0 replies; 7+ messages in thread
From: Al Viro @ 2015-11-10 2:31 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: netdev, David Miller, Eric Dumazet, Kostya Serebryany,
Alexander Potapenko, Sasha Levin, syzkaller, Alexey Kuznetsov
On Fri, Nov 06, 2015 at 01:58:27PM +0100, Dmitry Vyukov wrote:
> Hello,
>
> I am on revision d1e41ff11941784f469f17795a4d9425c2eb4b7a (Nov 5) and
> seeing the following lockdep reports. I don't have exact reproducer
> program as it is caused by several independent programs (state
> accumulated in kernel across invocations); if the report is not enough
> I can try to cook a reproducer.
>
> Thanks.
>
> [ INFO: possible circular locking dependency detected ]
> 4.3.0+ #30 Not tainted
> -------------------------------------------------------
> a.out/9972 is trying to acquire lock:
> (&pipe->mutex/1){+.+.+.}, at: [< inline >] pipe_lock_nested
> fs/pipe.c:59
> (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814d6e46>]
> pipe_lock+0x56/0x70 fs/pipe.c:67
>
> but task is already holding lock:
> (sb_writers#5){.+.+.+}, at: [<ffffffff814c77ec>]
> __sb_start_write+0xec/0x130 fs/super.c:1198
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #2
[AF_UNIX bind() does sb_start_write() while holding unix_sock locked]
> -> #1
[splice() to AF_UNIX socket is trying to lock unix_sock while holding
the pipe locked]
> -> #0 (&pipe->mutex/1){+.+.+.}:
[splice() to regular file is locking the pipe under sb_start_write()]
Cute... The first impression is that in #1 you need the socket to
be connected, or it won't even reach that attempt to lock unix_sock,
while bind() on the same sucker ought to bugger off before getting
around to touching the filesystem, so it looks like a false positive,
but... socketpair() yields a connected socket and AFAICS there's
nothing in unix_bind() to bugger off on such.
So the scenario ought to be:
(a while ago) A: socketpair()
B: splice() from a pipe to /mnt/regular_file
does sb_start_write() on /mnt
C: try to freeze /mnt
wait for B to finish with /mnt
A: bind() try to bind our socket to /mnt/new_socket_name
lock our socket, see it not bound yet
decide that it needs to create something in /mnt
try to do sb_start_write() on /mnt, block (it's
waiting for C).
D: splice() from the same pipe to our socket
lock the pipe, see that socket is connected
try to lock the socket, block waiting for A
B: get around to actually feeding a chunk from
pipe to file, try to lock the pipe. Deadlock.
Locking the socket is interruptible, though, so killing D will
untangle that mess - it's not quite a hopeless deadlock.
Deadlock or not, should bind() actually work on connected sockets?
AFAICS, socketpair() is the only way for it to happen...
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-06 15:42 ` Eric Dumazet
@ 2015-11-10 2:38 ` Al Viro
2015-11-10 2:59 ` Al Viro
0 siblings, 1 reply; 7+ messages in thread
From: Al Viro @ 2015-11-10 2:38 UTC (permalink / raw)
To: Eric Dumazet
Cc: Dmitry Vyukov, linux-fsdevel, linux-kernel, netdev, David Miller,
Eric Dumazet, Kostya Serebryany, Alexander Potapenko,
Sasha Levin, syzkaller, Alexey Kuznetsov
On Fri, Nov 06, 2015 at 07:42:15AM -0800, Eric Dumazet wrote:
> Thank you for this report.
>
> pipe is part of fs, not net ;)
AF_UNIX bind() vs. socketpair() interplay, OTOH...
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-10 2:38 ` Al Viro
@ 2015-11-10 2:59 ` Al Viro
2015-11-23 8:32 ` Dmitry Vyukov
0 siblings, 1 reply; 7+ messages in thread
From: Al Viro @ 2015-11-10 2:59 UTC (permalink / raw)
To: Eric Dumazet
Cc: Dmitry Vyukov, linux-fsdevel, linux-kernel, netdev, David Miller,
Eric Dumazet, Kostya Serebryany, Alexander Potapenko,
Sasha Levin, syzkaller, Alexey Kuznetsov
On Tue, Nov 10, 2015 at 02:38:54AM +0000, Al Viro wrote:
> On Fri, Nov 06, 2015 at 07:42:15AM -0800, Eric Dumazet wrote:
>
> > Thank you for this report.
> >
> > pipe is part of fs, not net ;)
>
> AF_UNIX bind() vs. socketpair() interplay, OTOH...
FWIW, BSD folks unlock the socket for the duration of mknod - mark it as
"somebody's trying to bind it" to avoid the fun with racing double bind(),
but that's about it. Tempting, to be honest...
BTW, why does unix_autobind() do allocation under ->readlock? The allocation
will be normally used - that if (u->addr) return; part is just dealing with
an unlikely race, as far as I can see...
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-10 2:59 ` Al Viro
@ 2015-11-23 8:32 ` Dmitry Vyukov
2015-11-23 9:21 ` Hannes Frederic Sowa
0 siblings, 1 reply; 7+ messages in thread
From: Dmitry Vyukov @ 2015-11-23 8:32 UTC (permalink / raw)
To: Al Viro
Cc: Eric Dumazet, linux-fsdevel, linux-kernel, netdev, David Miller,
Eric Dumazet, Kostya Serebryany, Alexander Potapenko,
Sasha Levin, syzkaller, Alexey Kuznetsov
On Tue, Nov 10, 2015 at 3:59 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Tue, Nov 10, 2015 at 02:38:54AM +0000, Al Viro wrote:
>> On Fri, Nov 06, 2015 at 07:42:15AM -0800, Eric Dumazet wrote:
>>
>> > Thank you for this report.
>> >
>> > pipe is part of fs, not net ;)
>>
>> AF_UNIX bind() vs. socketpair() interplay, OTOH...
>
> FWIW, BSD folks unlock the socket for the duration of mknod - mark it as
> "somebody's trying to bind it" to avoid the fun with racing double bind(),
> but that's about it. Tempting, to be honest...
>
> BTW, why does unix_autobind() do allocation under ->readlock? The allocation
> will be normally used - that if (u->addr) return; part is just dealing with
> an unlikely race, as far as I can see...
Hello,
This is still happening periodically for me. Is there a proposed fix?
I could test it.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Deadlock between bind and splice
2015-11-23 8:32 ` Dmitry Vyukov
@ 2015-11-23 9:21 ` Hannes Frederic Sowa
0 siblings, 0 replies; 7+ messages in thread
From: Hannes Frederic Sowa @ 2015-11-23 9:21 UTC (permalink / raw)
To: Dmitry Vyukov, Al Viro
Cc: Eric Dumazet, linux-fsdevel, linux-kernel, netdev, David Miller,
Eric Dumazet, Kostya Serebryany, Alexander Potapenko,
Sasha Levin, syzkaller, Alexey Kuznetsov
On Mon, Nov 23, 2015, at 09:32, Dmitry Vyukov wrote:
> On Tue, Nov 10, 2015 at 3:59 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > On Tue, Nov 10, 2015 at 02:38:54AM +0000, Al Viro wrote:
> >> On Fri, Nov 06, 2015 at 07:42:15AM -0800, Eric Dumazet wrote:
> >>
> >> > Thank you for this report.
> >> >
> >> > pipe is part of fs, not net ;)
> >>
> >> AF_UNIX bind() vs. socketpair() interplay, OTOH...
> >
> > FWIW, BSD folks unlock the socket for the duration of mknod - mark it as
> > "somebody's trying to bind it" to avoid the fun with racing double bind(),
> > but that's about it. Tempting, to be honest...
> >
> > BTW, why does unix_autobind() do allocation under ->readlock? The allocation
> > will be normally used - that if (u->addr) return; part is just dealing with
> > an unlikely race, as far as I can see...
>
>
> Hello,
>
> This is still happening periodically for me. Is there a proposed fix?
> I could test it.
No, we currently have no fix for that report. :/
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2015-11-23 9:21 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-11-06 12:58 Deadlock between bind and splice Dmitry Vyukov
2015-11-06 15:42 ` Eric Dumazet
2015-11-10 2:38 ` Al Viro
2015-11-10 2:59 ` Al Viro
2015-11-23 8:32 ` Dmitry Vyukov
2015-11-23 9:21 ` Hannes Frederic Sowa
2015-11-10 2:31 ` Al Viro
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