Re: [PATCH] ReiserFS: Make sure all dentries refs are released before calling kill_block_super()

From: Rafael J. Wysocki
Date: Tue Aug 08 2006 - 19:15:13 EST

On Tuesday 08 August 2006 19:23, David Howells wrote:
> Make sure all dentries refs are released before calling kill_block_super() so
> that the assumption that generic_shutdown_super() can completely destroy the
> dentry tree for there will be no external references holds true.
> What was being done in the put_super() superblock op, is now done in the
> kill_sb() filesystem op instead, prior to calling kill_block_super().
> This prevents the BUG_ON() in the reduced-locking dcache destroyer patch from
> barking at reiserfs.
> I've tested this patch by creating a ReiserFS partition, mounting and
> unmounting it a few times, and doing things to its contents whilst it is
> mounted.

It didn't apply cleanly to -rc3-mm2 for me and produces the appended oops
every time at the kernel startup (on x86_64).


input: SynPS/2 Synaptics TouchPad as /class/input/input2
RAMDISK: ext2 filesystem found at block 0
RAMDISK: Loading 2000KiB [1 disk] into ram disk... done.
Unable to handle kernel NULL pointer dereference at 0000000000000510 RIP:
[<ffffffff802edc73>] reiserfs_kill_sb+0x13/0xa0
Oops: 0000 [1] PREEMPT
last sysfs file: /block/hdc/range
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.18-rc3-mm2 #10
RIP: 0010:[<ffffffff802edc73>] [<ffffffff802edc73>] reiserfs_kill_sb+0x13/0xa0
RSP: 0000:ffff81005ff27a98 EFLAGS: 00010292
RAX: 0000000000000000 RBX: ffff810037c3ad20 RCX: 0000000000000003
RDX: 0000000000000008 RSI: ffff81005ff08798 RDI: ffff810037c3ad20
RBP: ffff81005ff27aa8 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff805778c0
R13: 0000000000000001 R14: ffff810037c23080 R15: ffff810037df8168
FS: 0000000000000000(0000) GS:ffffffff808c2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 0000000000000510 CR3: 0000000000201000 CR4: 00000000000006e0
Process swapper (pid: 1, threadinfo ffff81005ff26000, task ffff81005ff08040)
Stack: ffff810037c3ad20 ffff810037c3ad20 ffff81005ff27ac8 ffffffff80294671
00000000ffffffea ffff810037c3ad20 ffff81005ff27b38 ffffffff8029539f
ffffffff802ee260 0000000000000000 ffffff00306d6172 ffff810037df8168
Call Trace:
[<ffffffff80294671>] deactivate_super+0x81/0xa0
[<ffffffff8029539f>] get_sb_bdev+0x12f/0x180
[<ffffffff802ec653>] get_super_block+0x13/0x20
[<ffffffff80294746>] vfs_kern_mount+0xb6/0x160
[<ffffffff8029485a>] do_kern_mount+0x4a/0x70
[<ffffffff802ae370>] do_mount+0x720/0x790
[<ffffffff802ae474>] sys_mount+0x94/0xe0
[<ffffffff808d5b75>] mount_block_root+0xf5/0x2a0
[<ffffffff808d84d2>] initrd_load+0xc2/0x330
[<ffffffff808d5e43>] prepare_namespace+0xc3/0x140
[<ffffffff8020723c>] init+0x1dc/0x2c0
[<ffffffff8020a706>] child_rip+0x8/0x12
DWARF2 unwinder stuck at child_rip+0x8/0x12
Leftover inexact backtrace:
[<ffffffff80471edb>] _spin_unlock_irq+0x2b/0x60
[<ffffffff8020a2c0>] restore_args+0x0/0x30
[<ffffffff80207060>] init+0x0/0x2c0
[<ffffffff8020a6fe>] child_rip+0x0/0x12

Code: 48 8b b8 10 05 00 00 48 85 ff 74 31 e8 9c a3 fb ff 48 8b 83
RIP [<ffffffff802edc73>] reiserfs_kill_sb+0x13/0xa0
RSP <ffff81005ff27a98>
CR2: 0000000000000510
<0>Kernel panic - not syncing: Attempted to kill init!

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