BUG?: 2.4.5 breaks reiserfs (kernel BUG)

BUG?: 2.4.5 breaks reiserfs (kernel BUG)

[Bjerkeset, Svein Olav]

Hi,

Today I downloaded kernel 2.4.5 and compiled it. The kernel worked fine
until
I tried to halt the computer. When trying to unmount the reiserfs
filesystems,
the system freezes with the following output:

journal_begin called without kernel lock held
kernel BUG at journal.c:423!
invalid operand: 0000
CPU:    0
EIP:    0010:[<c01b5fb0>]
EFLAGS: 00210282
eax: 0000001d   ebx: c1eb1f28   ecx: c7ab2000   edx: 00000001
esi: c13c8200   edi: 3b11320b   ebp: 0000000a   esp: c1eb1ec0
ds: 0018   es: 0018   ss: 0018
Process umount (pid: 1027, stackpage=c1eb1000)
Stack: c02ef289 c02ef3e4 000001a7 c01b855b c02f0401 c1eb1f28 c13c8200
c034e020
       c13c8234 3b11320b 00000000 c67f55c0 c13c8200 c1eb0000 c13c8244
c01b876e
       c1eb1f28 c13c8200 0000000a 00000000 c01a92f8 c1eb1f28 c13c8200
0000000a
Call Trace: [<c01b855b>] [<c01b876e>] [<c01a92f8>] [<c0137baa>]
[<c0137be1>] [<c0136e8c>] [<c013cecc>]
       [<c013808d>] [<c0122f62>] [<c01380c4>] [<c0106efb>]

Code: 0f 0b 83 c4 0c c3 89 f6 31 c0 c3 90 31 c0 c3 90 56 be 40 2f


BTW: The kernel is compiled with egcs 2.91.66

Please CC to svbj@online.no as I am not subscribed to this list

Svein Olav Bjerkeset
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Re: BUG?: 2.4.5 breaks reiserfs (kernel BUG)

[Alexander Viro]

On Sun, 27 May 2001, Bjerkeset, Svein Olav wrote:

> Hi,
> 
> Today I downloaded kernel 2.4.5 and compiled it. The kernel worked fine
> until
> I tried to halt the computer. When trying to unmount the reiserfs
> filesystems,
> the system freezes with the following output:
> 
> journal_begin called without kernel lock held
> kernel BUG at journal.c:423!

	Yes. My fault - badly merged patch in -pre6, actually.
Details:
	* kill_super() gets called without BKL, but doesn't grab BKL around
the calls of ->write_super() and ->put_super()
	* by the time when it calls these methods filesystem is quiet. I.e.
nothing else has a chance to touch its data structures. So actually only
reiserfs (which checks that we hold BKL) had noticed.
	* It _is_ a bug - changing locking rules is for 2.5.

Fix:
--- fs/super.c	Fri May 25 21:51:14 2001
+++ fs/super.c	Sun May 27 00:21:53 2001
@@ -873,6 +873,7 @@
 	}
 	spin_unlock(&dcache_lock);
 	down_write(&sb->s_umount);
+	lock_kernel();
 	sb->s_root = NULL;
 	/* Need to clean after the sucker */
 	if (fs->fs_flags & FS_LITTER)
@@ -901,6 +902,7 @@
 	put_filesystem(fs);
 	sb->s_type = NULL;
 	unlock_super(sb);
+	unlock_kernel();
 	up_write(&sb->s_umount);
 	if (bdev) {
 		blkdev_put(bdev, BDEV_FS);