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From: Liu Bo <bo.li.liu@oracle.com>
To: Stefan Behrens <sbehrens@giantdisaster.de>
Cc: Mitch Harder <mitch.harder@sabayonlinux.org>,
	linux-btrfs@vger.kernel.org, chris.mason@fusionio.com,
	JBacik@fusionio.com, dave@jikos.cz, kitayama@cl.bb4u.ne.jp,
	miaox@cn.fujitsu.com
Subject: Re: [PATCH V5] Btrfs: snapshot-aware defrag
Date: Sun, 27 Jan 2013 21:19:53 +0800	[thread overview]
Message-ID: <20130127131952.GB16722@liubo> (raw)
In-Reply-To: <5102A76C.5050706@giantdisaster.de>

On Fri, Jan 25, 2013 at 04:40:28PM +0100, Stefan Behrens wrote:
> On Fri, 25 Jan 2013 08:55:58 -0600, Mitch Harder wrote:
> > On Wed, Jan 23, 2013 at 6:52 PM, Liu Bo <bo.li.liu@oracle.com> wrote:
> >> On Wed, Jan 23, 2013 at 10:05:04AM -0600, Mitch Harder wrote:
> 
[...]
> Well, the issue that I had reported on IRC some days ago which looks similar (the top part of the call trace is similar: iput -> evict -> destroy_inode -> btrfs_destroy_inode -> btrfs_add_dead_root -> list_add which warns in list_add in your case and crashes in my case) was without Liu Bo's "snapshot-aware defrag" patch. A 3.8.0-rc4 kernel and nothing else.
> 
> The reproducer was to create and destroy subvolumes and snapshots. I used btrfs-receive to fill them with data. The crash happened on umount. Every time.
> 
> del_fs_roots() is attempting to empty the dead_roots list, and via btrfs_destroy_inode() deeper in the call stack they are added back to the dead_roots list.
> 

Hi Stefan,

I assume that you're with 'inode_cache' option, since the iput() here
refers to
static void free_fs_root(struct btrfs_root *root)
{                                                                                
        iput(root->cache_inode);
	...
}

If my assumption is right, what about the following patch?

thanks,
liubo

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 65f0367..01a601b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3220,6 +3220,13 @@ static void del_fs_roots(struct btrfs_fs_info
*fs_info)
 	struct btrfs_root *gang[8];
 	int i;
 
+	list_for_each_entry(gang[0], &fs_info->dead_roots, root_list) {
+		if (gang[0]->in_radix) {
+			iput(root->cache_inode);
+			root->cache_inode = NULL;
+		}
+	}
+
 	while (!list_empty(&fs_info->dead_roots)) {
 		gang[0] = list_entry(fs_info->dead_roots.next,
 				     struct btrfs_root, root_list);


> BUG: unable to handle kernel paging request at ffff88042503b830
> IP: [<ffffffff814532b7>] __list_add+0x17/0xd0
> PGD 1e0c063 PUD bf58e067 PMD bf6b7067 PTE 800000042503b160
> Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> Modules linked in: btrfs bonding raid1 mpt2sas scsi_transport_sas raid_class
> CPU 2
> Pid: 10259, comm: umount Not tainted 3.8.0-rc4+ #16 Supermicro X8SIL/X8SIL
> RIP: 0010:[<ffffffff814532b7>]  [<ffffffff814532b7>] __list_add+0x17/0xd0
> RSP: 0018:ffff8802f67a1bd8  EFLAGS: 00010286
> RAX: ffff880425b7c560 RBX: ffff880423ca2828 RCX: 0000000000000001
> RDX: ffff88042503b828 RSI: ffff8804257794c0 RDI: ffff880423ca2828
> RBP: ffff8802f67a1bf8 R08: 0000000000077850 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000001 R12: ffff880423ca2000
> R13: ffff880423ca2898 R14: 0000000000000000 R15: ffff8802f67a1d30
> FS:  00007f6e89bba740(0000) GS:ffff88042ea00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: ffff88042503b830 CR3: 000000029a56c000 CR4: 00000000000007e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process umount (pid: 10259, threadinfo ffff8802f67a0000, task ffff880425b7c560)
> Stack:
>  ffffffffa00a414f ffff880423ca2000 ffff880423ca2000 ffff880423ca2898
>  ffff8802f67a1c18 ffffffffa00a4170 ffff88042a60c1f8 ffff88042a60c1f8
>  ffff8802f67a1c48 ffffffffa00b3180 ffff88042a60c1f8 ffff88042a60c280
> Call Trace:
>  [<ffffffffa00a414f>] ? btrfs_add_dead_root+0x1f/0x60 [btrfs]
>  [<ffffffffa00a4170>] btrfs_add_dead_root+0x40/0x60 [btrfs]
>  [<ffffffffa00b3180>] btrfs_destroy_inode+0x1d0/0x2d0 [btrfs]
>  [<ffffffff811b5d17>] destroy_inode+0x37/0x60
>  [<ffffffff811b5e4d>] evict+0x10d/0x1a0
>  [<ffffffff811b65f5>] iput+0x105/0x190
>  [<ffffffffa009bd68>] free_fs_root+0x18/0x90 [btrfs]
>  [<ffffffffa009f1ab>] btrfs_free_fs_root+0x7b/0x90 [btrfs]
>  [<ffffffffa009f26f>] del_fs_roots+0xaf/0xf0 [btrfs]
>  [<ffffffffa00a0bc6>] close_ctree+0x1c6/0x300 [btrfs]
>  [<ffffffff811b6a7c>] ? evict_inodes+0xec/0x100
>  [<ffffffffa00763a4>] btrfs_put_super+0x14/0x20 [btrfs]
>  [<ffffffff8119dfcc>] generic_shutdown_super+0x5c/0xe0
>  [<ffffffff8119e0e1>] kill_anon_super+0x11/0x20
>  [<ffffffffa007a3a5>] btrfs_kill_super+0x15/0x90 [btrfs]
>  [<ffffffff8119f111>] ? deactivate_super+0x41/0x70
>  [<ffffffff8119e4dd>] deactivate_locked_super+0x3d/0x70
>  [<ffffffff8119f119>] deactivate_super+0x49/0x70
>  [<ffffffff811ba772>] mntput_no_expire+0xd2/0x130
>  [<ffffffff811bb621>] sys_umount+0x71/0x390
>  [<ffffffff81983012>] system_call_fastpath+0x16/0x1b
> Code: 48 83 c4 08 5b 5d c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 4c 89 65 f0 48 89 fb 4c 89 6d f8 <4c> 8b 42 08 49 89 f5 49 89 d4 49 39 f0 75 31 4d 8b 45 00 4d 39
> RIP  [<ffffffff814532b7>] __list_add+0x17/0xd0
>  RSP <ffff8802f67a1bd8>
> CR2: ffff88042503b830
> ---[ end trace 5e44f1afc74751aa ]---
> 

  reply	other threads:[~2013-01-27 13:22 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-16 12:36 [PATCH V5] Btrfs: snapshot-aware defrag Liu Bo
2013-01-17 14:42 ` Mitch Harder
2013-01-18  0:53   ` Liu Bo
2013-01-18  5:23     ` Mitch Harder
2013-01-18 12:19   ` David Sterba
2013-01-18 22:01     ` Mitch Harder
2013-01-22 17:41   ` Mitch Harder
2013-01-23  7:51     ` Liu Bo
2013-01-23 16:05       ` Mitch Harder
2013-01-24  0:52         ` Liu Bo
2013-01-25 14:55           ` Mitch Harder
2013-01-25 15:40             ` Stefan Behrens
2013-01-27 13:19               ` Liu Bo [this message]
2013-01-28 16:55                 ` Stefan Behrens
2013-02-16  6:47                   ` Liu Bo
2013-02-18 16:53                     ` Stefan Behrens
2013-02-19  4:29                       ` Liu Bo
2013-02-19 17:53                         ` Stefan Behrens
2013-01-25 15:42             ` Liu Bo
2013-01-25 18:16               ` Mitch Harder
2013-01-27 12:41                 ` Liu Bo
2013-01-28  5:20                   ` Mitch Harder
2013-01-28  6:54                     ` Liu Bo

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