[Bug 42859] New: kernel BUG at fs/ext4/extents.c:1953

[Bug 42859] New: kernel BUG at fs/ext4/extents.c:1953

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=42859

           Summary: kernel BUG at fs/ext4/extents.c:1953
           Product: File System
           Version: 2.5
    Kernel Version: 3.2.1, 3.2.9
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
        AssignedTo: fs_ext4@kernel-bugs.osdl.org
        ReportedBy: merll@web.de
        Regression: No


Messages "kernel BUG at fs/ext4/extents.c:1953" occur, which seem to be
triggered when running certain processes (reproducible with init and gdm). The
volume can be mounted without any apparent problems and e2fsck does not report
any errors. Nevertheless, the file system may have been corrupted during an
earlier system crash.

For example, the following message can be produced when running "shutdown -r
now":

------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:1953!
invalid opcode: 0000 [#1] SMP 
CPU 0 
Modules linked in: vfat fat firewire_sbp2 uvcvideo videodev firewire_ohci
snd_usb_audio firewire_core btusb v4l2_compat_ioctl32 crc_itu_t snd_usbmidi_lib
bluetooth snd_rawmidi

Pid: 1, comm: init Not tainted 3.2.9-gentoo #4 Gigabyte Technology Co., Ltd.
EX38-DS4/EX38-DS4
RIP: 0010:[<ffffffff81194746>]  [<ffffffff81194746>]
ext4_ext_put_in_cache+0x76/0x80
RSP: 0018:ffff88011aa4d7a8  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88011acc5350 RCX: 0000000000508274
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88011acc5350
RBP: 0000000000000000 R08: ffff880119427ae0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000508274 R12: 0000000000000000
R13: ffff880119b81800 R14: 0000000000508274 R15: 0000000000000000
FS:  00007f8703c7d700(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff54d5fff8 CR3: 000000011ab1a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process init (pid: 1, threadinfo ffff88011aa4c000, task ffff88011aa58000)
Stack:
ffff880119427ae0 ffff88011aa4d998 ffff88011acc5350 ffff880119b81800
ffff88011acc52cc ffffffff8119780f 0000000100014341 ffff88011fffbe00
ffff88011fffbe00 ffffffff810e720d 0000000000000000 0000000000508274
Call Trace:
[<ffffffff8119780f>] ? ext4_ext_map_blocks+0x15f/0x1b00
[<ffffffff810e720d>] ? zone_statistics+0x9d/0xa0
[<ffffffff810d78f9>] ? get_page_from_freelist+0x309/0x720
[<ffffffff8144ab9e>] ? __schedule+0x29e/0x740
[<ffffffff8117ec61>] ? ext4_da_get_block_prep+0x141/0x2c0
[<ffffffff8113eb31>] ? alloc_page_buffers+0x71/0xe0
[<ffffffff81141316>] ? __block_write_begin+0x206/0x560
[<ffffffff8117eb20>] ? ext4_bmap+0x110/0x110
[<ffffffff81180d47>] ? ext4_da_write_begin+0xc7/0x1c0
[<ffffffff81061183>] ? __wake_up+0x43/0x70
[<ffffffff810d0860>] ? generic_file_buffered_write+0x120/0x2c0
[<ffffffff810d2469>] ? __generic_file_aio_write+0x219/0x410
[<ffffffff810d8453>] ? __alloc_pages_nodemask+0x123/0x810
[<ffffffff810d26d9>] ? generic_file_aio_write+0x79/0x100
[<ffffffff8117b20e>] ? ext4_file_write+0x6e/0x290
[<ffffffff8110454e>] ? alloc_pages_vma+0x5e/0x220
[<ffffffff81114ddf>] ? do_sync_write+0xbf/0x100
[<ffffffff8115797f>] ? fcntl_setlk+0x5f/0x330
[<ffffffff81115646>] ? vfs_write+0xc6/0x170
[<ffffffff8111592e>] ? sys_write+0x4e/0x90
[<ffffffff8144d8bb>] ? system_call_fastpath+0x16/0x1b
Code: 00 4d 89 b5 98 02 00 00 fe 83 7c 02 00 00 48 8b 1c 24 48 8b 6c 24 08 4c
8b 64 24 10 4c 8b 6c 24 18 4c 8b 74 24 20 48 83 c4 28 c3 <0f> 0b 0f 1f 84 00 00
00 00 00 41 57 41 56 41 55 41 54 49 89 cc
RIP  [<ffffffff81194746>] ext4_ext_put_in_cache+0x76/0x80
RSP <ffff88011aa4d7a8>
---[ end trace 050481fbd074e5e1 ]---

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Re: [Bug 42859] New: kernel BUG at fs/ext4/extents.c:1953

[Ted Ts'o]

On Sun, Mar 04, 2012 at 02:39:09PM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> Messages "kernel BUG at fs/ext4/extents.c:1953" occur, which seem to be
> triggered when running certain processes (reproducible with init and gdm). The
> volume can be mounted without any apparent problems and e2fsck does not report
> any errors. Nevertheless, the file system may have been corrupted during an
> earlier system crash.

Would you be willing to apply the following patch, and then see which
inode number gets reported (and whether it is always the same inode
number or one that varies) and then report back the results of running
the following debugfs commands?

(assuming the inode number is 12345)

debugfs /dev/sdX

debugfs: stat <12345>
degbufs: ex <12345>

Thanks!!

					- Ted

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 74f23c2..0393542 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1949,7 +1949,13 @@ ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
 			__u32 len, ext4_fsblk_t start)
 {
 	struct ext4_ext_cache *cex;
-	BUG_ON(len == 0);
+	if (unlikely(len == 0)) {
+		ext4_msg(inode->i_sb, KERN_CRIT,
+			 "ext4_put_in_cache has len == 0: "
+			 "ino %u, lblk %lu, pblk %llu", inode->i_ino,
+			 block, start);
+		BUG_ON(1);
+	}
 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 	trace_ext4_ext_put_in_cache(inode, block, len, start);
 	cex = &EXT4_I(inode)->i_cached_extent;

Re: [Bug 42859] New: kernel BUG at fs/ext4/extents.c:1953

[Matthias Erll]

Hi Ted,

Am 04.03.12 21:27, schrieb Ted Ts'o:
> On Sun, Mar 04, 2012 at 02:39:09PM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
>> Messages "kernel BUG at fs/ext4/extents.c:1953" occur, which seem to be
>> triggered when running certain processes (reproducible with init and gdm). The
>> volume can be mounted without any apparent problems and e2fsck does not report
>> any errors. Nevertheless, the file system may have been corrupted during an
>> earlier system crash.
> Would you be willing to apply the following patch, and then see which
> inode number gets reported (and whether it is always the same inode
> number or one that varies) and then report back the results of running
> the following debugfs commands?
>
> (assuming the inode number is 12345)
>
> debugfs /dev/sdX
>
> debugfs: stat <12345>
> degbufs: ex <12345>

In the three cases I can reproduce, the inode number has been identical.
Please find the debugfs output below.

Kind regards,
Matthias




debugfs /dev/sda2
debugfs 1.42.1 (17-Feb-2012)

debugfs: stat <1312385>
Inode: 1312385   Type: regular    Mode:  0664   Flags: 0x80000
Generation: 1339335381    Version: 0x00000000:00000001
User:     0   Group:   406   Size: 0
File ACL: 0    Directory ACL: 0
Links: 1   Blockcount: 0
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x4f53e0ab:3c51ed20 -- Sun Mar  4 22:37:47 2012
 atime: 0x4eda803c:da6fb35c -- Sat Dec  3 21:02:04 2011
 mtime: 0x4f53e0ab:3bd7da30 -- Sun Mar  4 22:37:47 2012
crtime: 0x4eda803c:da6fb35c -- Sat Dec  3 21:02:04 2011
Size of extra inode fields: 28
EXTENTS:

debugfs: ex <1312385>
Level Entries       Logical          Physical Length Flags
 0/ 0   1/  1     0 - 4294967295 5276276 - 4300243571      0

Re: [Bug 42859] New: kernel BUG at fs/ext4/extents.c:1953

[Ted Ts'o]

On Sun, Mar 04, 2012 at 11:11:00PM +0100, Matthias Erll wrote:
> 
> In the three cases I can reproduce, the inode number has been identical.
> Please find the debugfs output below.

Thanks, this is helpful.  It is indeed a bug in e2fsck; it's not
noticing the case where the extent length is zero (but the extent
header was still valid).  The workaround is to run the following
commands with the file system unmounted:

# debugfs -w -R "clri <1312385>" /dev/sda2
# e2fsck -f /dev/sda2

I'll get this fixed in the next maintenance release of e2fsprogs.

     	      	       	   	- Ted

[Bug 42859] kernel BUG at fs/ext4/extents.c:1953

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=42859


Florian Mickler <florian@mickler.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |florian@mickler.org




--- Comment #1 from Florian Mickler <florian@mickler.org>  2012-04-04 14:59:31 ---
A patch referencing this bug report has been merged in Linux v3.4-rc1:

commit 31d4f3a2f3c73f279ff96a7135d7202ef6833f12
Author: Theodore Ts'o <tytso@mit.edu>
Date:   Sun Mar 11 23:30:16 2012 -0400

    ext4: check for zero length extent

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[Bug 42859] kernel BUG at fs/ext4/extents.c:1953

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=42859


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |alan@lxorguk.ukuu.org.uk
         Resolution|                            |CODE_FIX




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[Bug 42859] kernel BUG at fs/ext4/extents.c:1953

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=42859


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED




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[Bug 42859] kernel BUG at fs/ext4/extents.c:1953

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=42859

basitali152633@gmail.com (basitali152633@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |basitali152633@gmail.com

--- Comment #2 from basitali152633@gmail.com (basitali152633@gmail.com) ---
Good work.Thanks for sharing.
http://crackorg.com/

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