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Message-Id: <200704191643.38367.vs@namesys.com>
Date: Thu, 19 Apr 2007 16:43:37 +0400
From: "Vladimir V. Saveliev" <vs@...esys.com>
To: Jens Axboe <jens.axboe@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-aio@...ck.org,
reiserfs-dev@...esys.com, linux-mm@...ck.org
Subject: Re: dio_get_page() lockdep complaints
Hello
On Thursday 19 April 2007 12:34, Jens Axboe wrote:
> On Thu, Apr 19 2007, Andrew Morton wrote:
> > On Thu, 19 Apr 2007 10:01:57 +0200 Jens Axboe <jens.axboe@...cle.com> wrote:
> >
> > > On Thu, Apr 19 2007, Andrew Morton wrote:
> > > > On Thu, 19 Apr 2007 09:38:30 +0200 Jens Axboe <jens.axboe@...cle.com> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > Doing some testing on CFQ, I ran into this 100% reproducible report:
> > > > >
> > > > > =======================================================
> > > > > [ INFO: possible circular locking dependency detected ]
> > > > > 2.6.21-rc7 #5
> > > > > -------------------------------------------------------
> > > > > fio/9741 is trying to acquire lock:
> > > > > (&mm->mmap_sem){----}, at: [<b018cb34>] dio_get_page+0x54/0x161
> > > > >
> > > > > but task is already holding lock:
> > > > > (&inode->i_mutex){--..}, at: [<b038c6e5>] mutex_lock+0x1c/0x1f
> > > > >
> > > > > which lock already depends on the new lock.
> > > > >
> > > >
> > > > This is the correct ranking: i_mutex outside mmap_sem.
> > > >
> > > > >
> > > > > the existing dependency chain (in reverse order) is:
> > > > >
> > > > > -> #1 (&inode->i_mutex){--..}:
> > > > > [<b013e3fb>] __lock_acquire+0xdee/0xf9c
> > > > > [<b013e600>] lock_acquire+0x57/0x70
> > > > > [<b038c4a5>] __mutex_lock_slowpath+0x73/0x297
> > > > > [<b038c6e5>] mutex_lock+0x1c/0x1f
> > > > > [<b01b17e9>] reiserfs_file_release+0x54/0x447
> > > > > [<b016afe7>] __fput+0x53/0x101
> > > > > [<b016b0ee>] fput+0x19/0x1c
> > > > > [<b015bcd5>] remove_vma+0x3b/0x4d
> > > > > [<b015c659>] do_munmap+0x17f/0x1cf
> > > > > [<b015c6db>] sys_munmap+0x32/0x42
> > > > > [<b0103f04>] sysenter_past_esp+0x5d/0x99
> > > > > [<ffffffff>] 0xffffffff
> > > > >
> > > > > -> #0 (&mm->mmap_sem){----}:
> > > > > [<b013e259>] __lock_acquire+0xc4c/0xf9c
> > > > > [<b013e600>] lock_acquire+0x57/0x70
> > > > > [<b0137b92>] down_read+0x3a/0x4c
> > > > > [<b018cb34>] dio_get_page+0x54/0x161
> > > > > [<b018d7a9>] __blockdev_direct_IO+0x514/0xe2a
> > > > > [<b01cf449>] ext3_direct_IO+0x98/0x1e5
> > > > > [<b014e8df>] generic_file_direct_IO+0x63/0x133
> > > > > [<b01500e9>] generic_file_aio_read+0x16b/0x222
> > > > > [<b017f8b6>] aio_rw_vect_retry+0x5a/0x116
> > > > > [<b0180147>] aio_run_iocb+0x69/0x129
> > > > > [<b0180a78>] io_submit_one+0x194/0x2eb
> > > > > [<b0181331>] sys_io_submit+0x92/0xe7
> > > > > [<b0103f90>] syscall_call+0x7/0xb
> > > > > [<ffffffff>] 0xffffffff
> > > >
> > > > But here reiserfs is taking i_mutex in its file_operations.release(),
> > > > which can be called under mmap_sem.
> > > >
> > > > Vladimir's recent de14569f94513279e3d44d9571a421e9da1759ae.
> > > > "resierfs: avoid tail packing if an inode was ever mmapped" comes real
> > > > close to this code, but afaict it did not cause this bug.
> > > >
> > > > I can't think of anything which we've done in the 2.6.21 cycle which
> > > > would have caused this to start happening. Odd.
> > >
> > > The bug may be holder, let me know if you want me to check 2.6.20 or
> > > earlier.
> >
> > Would be great if you could test 2.6.20. I have a feeling that I missed
> > something, but what? We didn't change the refcounting of lifetime of
> > vma.vm_file...
>
> 2.6.20.7 tested, same lockdep triggers. Attached for reference.
>
Did you have CFQ patches mentioned below applied?
Would you please send your .config?
I tried fio (1.15) with this job file and did not get the possible circular locking dependency detected
> > > > > The test run was fio, the job file used is:
> > > > >
> > > > > # fio job file snip below
> > > > > [global]
> > > > > bs=4k
> > > > > buffered=0
> > > > > ioengine=libaio
> > > > > iodepth=4
> > > > > thread
> > > > >
> > > > > [readers]
> > > > > numjobs=8
> > > > > size=128m
> > > > > rw=read
> > > > > # fio job file snip above
> > > > >
> > > > > Filesystem was ext3, default mkfs and mount options. Kernel was
> > > > > 2.6.21-rc7 as of this morning, with some CFQ patches applied.
> > > > >
> > > >
> > > > It's interesting that lockdep learned the (wrong) ranking from a reiserfs
> > > > operation then later detected it being violated by ext3.
> > >
> > > It's a scratch test box, which for some reason has reiserfs as the
> > > rootfs. So reiser gets to run first :-)
> >
> > direct-io reads against reiserfs also will take i_mutex outside mmap_sem.
> > As will pagefaults inside generic_file_write() (which is where this ranking
> > is primarily defined).
> >
> > So an all-reiserfs system should be getting the same reports. Obviously,
> > that isn't happening.
> >
> > It's a bit odd that reiserfs is playing with file contents within
> > file_operations.release(): there could be other files open against that
> > inode. One would expect this sort of thing to be happening in an
> > inode_operation. But it's been like that for a long time.
> >
> > Is it possible that fio was changed? That it was changed to close() the fd
> > before doing the munmapping whereas it used to hold the file open?
>
> It's been a while since I tested on this box, so I don't really recall.
> But fio does close() the fd before doing munmap(). This particular test
> case doesn't use mmap(), though.
>
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.20.7 #1
> -------------------------------------------------------
> fio/6651 is trying to acquire lock:
> (&mm->mmap_sem){----}, at: [<b01899c4>] dio_get_page+0x54/0x161
>
> but task is already holding lock:
> (&inode->i_mutex){--..}, at: [<b0385e85>] mutex_lock+0x1c/0x1f
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&inode->i_mutex){--..}:
> [<b013ba73>] __lock_acquire+0xc86/0xd64
> [<b013bba8>] lock_acquire+0x57/0x70
> [<b0385c45>] __mutex_lock_slowpath+0x73/0x297
> [<b0385e85>] mutex_lock+0x1c/0x1f
> [<b01ae3b5>] reiserfs_file_release+0x54/0x44b
> [<b0167b27>] __fput+0x53/0x101
> [<b0167c2e>] fput+0x19/0x1c
> [<b015884c>] remove_vma+0x37/0x49
> [<b01591d0>] do_munmap+0x17f/0x1d0
> [<b0159253>] sys_munmap+0x32/0x42
> [<b0102f04>] sysenter_past_esp+0x5d/0x99
> [<ffffffff>] 0xffffffff
>
> -> #0 (&mm->mmap_sem){----}:
> [<b013b8f5>] __lock_acquire+0xb08/0xd64
> [<b013bba8>] lock_acquire+0x57/0x70
> [<b013701e>] down_read+0x3a/0x4c
> [<b01899c4>] dio_get_page+0x54/0x161
> [<b018a639>] __blockdev_direct_IO+0x514/0xe2a
> [<b01cc009>] ext3_direct_IO+0x98/0x1e5
> [<b014b72b>] generic_file_direct_IO+0x63/0x133
> [<b014cf79>] generic_file_aio_read+0x16b/0x222
> [<b017c466>] aio_rw_vect_retry+0x5a/0x116
> [<b017ccf7>] aio_run_iocb+0x69/0x129
> [<b017d6ed>] io_submit_one+0x194/0x2ec
> [<b017dffb>] sys_io_submit+0x92/0xe6
> [<b0102f90>] syscall_call+0x7/0xb
> [<ffffffff>] 0xffffffff
>
> other info that might help us debug this:
>
> 1 lock held by fio/6651:
> #0: (&inode->i_mutex){--..}, at: [<b0385e85>] mutex_lock+0x1c/0x1f
>
> stack backtrace:
> [<b0103f54>] show_trace_log_lvl+0x1a/0x30
> [<b01045f6>] show_trace+0x12/0x14
> [<b010467d>] dump_stack+0x16/0x18
> [<b0139d29>] print_circular_bug_tail+0x68/0x71
> [<b013b8f5>] __lock_acquire+0xb08/0xd64
> [<b013bba8>] lock_acquire+0x57/0x70
> [<b013701e>] down_read+0x3a/0x4c
> [<b01899c4>] dio_get_page+0x54/0x161
> [<b018a639>] __blockdev_direct_IO+0x514/0xe2a
> [<b01cc009>] ext3_direct_IO+0x98/0x1e5
> [<b014b72b>] generic_file_direct_IO+0x63/0x133
> [<b014cf79>] generic_file_aio_read+0x16b/0x222
> [<b017c466>] aio_rw_vect_retry+0x5a/0x116
> [<b017ccf7>] aio_run_iocb+0x69/0x129
> [<b017d6ed>] io_submit_one+0x194/0x2ec
> [<b017dffb>] sys_io_submit+0x92/0xe6
> [<b0102f90>] syscall_call+0x7/0xb
> =======================
>
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