On Tuesday 05 April 2011 19:42:03 Josef Bacik wrote:
> On Tue, Apr 05, 2011 at 07:38:13PM +0200, Johannes Hirte wrote:
> > With the latest btrfs changes, I got this Oops when doing rm on a large
> > directory:
> >
> > BUG: unable to handle kernel NULL pointer dereference at (null)
> > IP: [<c101c838>] kunmap+0x46/0x46
> > *pdpt = 0000000034a85001 *pde = 0000000000000000
> > Oops: 0000 [#1] PREEMPT SMP
> > last sysfs file: /sys/devices/virtual/vtconsole/vtcon1/uevent
> > Modules linked in: snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device
> > snd_pcm_oss snd_mixer_oss fuse dm_crypt dm_mod usbhid snd_intel8x0
> > snd_ac97_codec ac97_bus snd_pcm snd_timer sr_mod cdrom sg snd fschmd
> > e1000 uhci_hcd snd_page_alloc i2c_i801 [last unloaded: microcode]
> >
> > Pid: 1156, comm: btrfs-transacti Tainted: G W 2.6.39-rc1-00262-
> > gc53813f #20 FUJITSU SIEMENS SCENIC P / SCENICO P/D1561
> > EIP: 0060:[<c101c838>] EFLAGS: 00010296 CPU: 1
> > EIP is at kmap+0x0/0x38
> > EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000010
> > ESI: f5bc6400 EDI: f3c75520 EBP: f3c755f0 ESP: f58f9e10
> >
> > DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
> >
> > Process btrfs-transacti (pid: 1156, ti=f58f8000 task=f6516f40
> > task.ti=f58f8000)
> >
> > Stack:
> > c1186d15 ffc22000 f58f9ec0 00000010 f3c75610 00000000 f5885780 f52339e8
> > 00000009 f5bc6400 00010000 00000000 f6415800 f3c75638 000008bb f5bc63c0
> > f58857b4 f60b68a0 00000040 f52338e8 ffc22000 00000000 00000008 00000010
> >
> > Call Trace:
> > [<c1186d15>] ? btrfs_write_out_cache+0x60c/0xa3c
> > [<c114a815>] ? btrfs_write_dirty_block_groups+0x400/0x494
> > [<c11566a7>] ? commit_cowonly_roots+0xa9/0x180
> > [<c1157799>] ? btrfs_commit_transaction+0x2ee/0x59c
> > [<c1037c85>] ? wake_up_bit+0x16/0x16
> > [<c1152a83>] ? transaction_kthread+0x149/0x1d6
> > [<c101d1b9>] ? complete+0x28/0x36
> > [<c115293a>] ? btrfs_congested_fn+0x5d/0x5d
> > [<c10379c4>] ? kthread+0x63/0x68
> > [<c1037961>] ? kthread_worker_fn+0xeb/0xeb
> > [<c13cba36>] ? kernel_thread_helper+0x6/0xd
> >
> > Code: 8d 8a 00 e4 54 c1 2b 8a 8c e7 54 c1 81 f9 00 08 00 00 74 11 81 f9
> > 00 0c 00 00 75 0e 83 3d 10 2f 60 c1 02 75 05 e9 5e a3 04 00 c3 <8b> 10
> > c1 ea 1e c1 e2 0a 8d 8a 00 e4 54 c1 2b 8a 8c e7 54 c1 81
> > EIP: [<c101c838>] kmap+0x0/0x38 SS:ESP 0068:f58f9e10
> > CR2: 0000000000000000
> > ---[ end trace c8511126ee91dfdf ]---
> >
> > This is the second Oops. On the first one I wasn't able to catch the
> > backtrace, but IIRC the bug happend on kmap not kunmap the first time.
>
> Yeah I think I know what this is but I need somebody to verify it for me.
> Can you run with this patch and let me know what happens? Thanks,
>
> Josef
>
> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> index 74bc432..5e6f4b3 100644
> --- a/fs/btrfs/free-space-cache.c
> +++ b/fs/btrfs/free-space-cache.c
> @@ -624,6 +624,7 @@ int btrfs_write_out_cache(struct btrfs_root *root,
>
> next_page = false;
>
> + BUG_ON(index > last_index);
> if (index == 0) {
> start_offset = first_page_offset;
> offset = start_offset;
> @@ -732,6 +733,7 @@ int btrfs_write_out_cache(struct btrfs_root *root,
> struct btrfs_free_space *entry =
> list_entry(pos, struct btrfs_free_space, list);
>
> + BUG_ON(index > last_index);
> page = find_get_page(inode->i_mapping, index);
>
> addr = kmap(page);
Hm, I tried but now I hit the
BUG_ON(block_group->total_bitmaps >= max_bitmaps); in add_new_bitmap in
fs/btrfs/free-space-cache.c:1255 when booting the system.
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