From: Dave Chinner <david@fromorbit.com>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 0/6 v3] xfs: lockless buffer lookups
Date: Thu, 14 Jul 2022 11:32:01 +1000 [thread overview]
Message-ID: <20220714013201.GP3861211@dread.disaster.area> (raw)
In-Reply-To: <Ys76W8V72KJmXN+B@magnolia>
On Wed, Jul 13, 2022 at 10:01:15AM -0700, Darrick J. Wong wrote:
> On Fri, Jul 08, 2022 at 09:52:53AM +1000, Dave Chinner wrote:
> > Hi folks,
> >
> > Current work to merge the XFS inode life cycle with the VFS indoe
> > life cycle is finding some interesting issues. If we have a path
> > that hits buffer trylocks fairly hard (e.g. a non-blocking
> > background inode freeing function), we end up hitting massive
> > contention on the buffer cache hash locks:
>
> Hmm. I applied this to a test branch and this fell out of xfs/436 when
> it runs rmmod xfs. I'll see if I can reproduce it more regularly, but
> thought I'd put this out there early...
>
> XFS (sda3): Unmounting Filesystem
> =============================================================================
> BUG xfs_buf (Not tainted): Objects remaining in xfs_buf on __kmem_cache_shutdown()
> -----------------------------------------------------------------------------
>
> Slab 0xffffea000443b780 objects=18 used=4 fp=0xffff888110edf340 flags=0x17ff80000010200(slab|head|node=0|zone=2|lastcpupid=0xfff)
> CPU: 3 PID: 30378 Comm: modprobe Not tainted 5.19.0-rc5-djwx #rc5 bebda13a030d0898279476b6652ddea67c2060cc
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20171121_152543-x86-ol7-builder-01.us.oracle.com-4.el7.1 04/01/2014
> Call Trace:
> <TASK>
> dump_stack_lvl+0x34/0x44
> slab_err+0x95/0xc9
> __kmem_cache_shutdown.cold+0x39/0x1e9
> kmem_cache_destroy+0x49/0x130
> exit_xfs_fs+0x50/0xc57 [xfs 370e1c994a59de083c05cd4df389f629878b8122]
> __do_sys_delete_module.constprop.0+0x145/0x220
> ? exit_to_user_mode_prepare+0x6c/0x100
> do_syscall_64+0x35/0x80
> entry_SYSCALL_64_after_hwframe+0x46/0xb0
> RIP: 0033:0x7fe7d7877c9b
> Code: 73 01 c3 48 8b 0d 95 21 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 65 21 0f 00 f7 d8 64 89 01 48
> RSP: 002b:00007fffb911cab8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
> RAX: ffffffffffffffda RBX: 0000555a217adcc0 RCX: 00007fe7d7877c9b
> RDX: 0000000000000000 RSI: 0000000000000800 RDI: 0000555a217add28
> RBP: 0000555a217adcc0 R08: 0000000000000000 R09: 0000000000000000
> R10: 00007fe7d790fac0 R11: 0000000000000206 R12: 0000555a217add28
> R13: 0000000000000000 R14: 0000555a217add28 R15: 00007fffb911ede8
> </TASK>
> Disabling lock debugging due to kernel taint
> Object 0xffff888110ede000 @offset=0
> Object 0xffff888110ede1c0 @offset=448
> Object 0xffff888110edefc0 @offset=4032
> Object 0xffff888110edf6c0 @offset=5824
Curious, I haven't seen anything from KASAN that would indicate a
leak is occurring, and unmount can't occur while there are still
referenced buffers in the system. So what might be leaking is a bit
of a mystery to me right now...
Is this a result of xfs/436 running by itself, or left over from
some other prior test? i.e. if you add a '_reload_fs_module "xfs"'
call before the test does anything, does it complain?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2022-07-14 1:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 23:52 [PATCH 0/6 v3] xfs: lockless buffer lookups Dave Chinner
2022-07-07 23:52 ` [PATCH 1/6] xfs: rework xfs_buf_incore() API Dave Chinner
2022-07-07 23:52 ` [PATCH 2/6] xfs: break up xfs_buf_find() into individual pieces Dave Chinner
2022-07-09 22:58 ` Darrick J. Wong
2022-07-07 23:52 ` [PATCH 3/6] xfs: merge xfs_buf_find() and xfs_buf_get_map() Dave Chinner
2022-07-10 0:15 ` Darrick J. Wong
2022-07-11 5:14 ` Christoph Hellwig
2022-07-12 0:01 ` Dave Chinner
2022-07-07 23:52 ` [PATCH 4/6] xfs: reduce the number of atomic when locking a buffer after lookup Dave Chinner
2022-07-07 23:52 ` [PATCH 5/6] xfs: remove a superflous hash lookup when inserting new buffers Dave Chinner
2022-07-07 23:52 ` [PATCH 6/6] xfs: lockless buffer lookup Dave Chinner
2022-07-10 0:15 ` Darrick J. Wong
2022-07-13 17:01 ` [PATCH 0/6 v3] xfs: lockless buffer lookups Darrick J. Wong
2022-07-13 17:03 ` Darrick J. Wong
2022-07-14 1:32 ` Dave Chinner [this message]
2022-07-14 2:11 ` Darrick J. Wong
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