2011-06-19 10:14:47

by halfdog

Subject: Can someone confirm ext4 BUG_ON on latest kernel build?

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Sorry, I do not have latest kernel. Can someone confirm this on latest?
At least bugtracker does not know about it, and to my understanding of
source, should be still here.


dd if=/dev/zero bs=1M count=64 of=test
mkfs.ext4 -F test
echo -n " " | dd of=test bs=1 count=1 seek=297195 conv=notrunc
mount -o loop test /mnt/test
dmesg -c

On ubuntu natty with latest kernel, it seems, that
fs/ext4/super.c:__save_error_info calls mod_timer before timer->function
is set at end of fs/ext4/super.c:ext4_fill_super via
sbi->s_err_report.function = print_daily_error_info;

This causes BUG_ON(!timer->function) in kernel/timer.c:__mod_timer
Device is stuck, not usable any more.

Thanks

- --
http://www.halfdog.net/
PGP: 156A AE98 B91F 0114 FE88 2BD8 C459 9386 feed a bee
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2011-06-19 15:07:10

by Randy Dunlap

Subject: Re: Can someone confirm ext4 BUG_ON on latest kernel build?

[adding ext4 mailing list]


On Sun, 19 Jun 2011 10:13:52 +0000 halfdog wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Sorry, I do not have latest kernel. Can someone confirm this on latest?
> At least bugtracker does not know about it, and to my understanding of
> source, should be still here.
>
>
> dd if=/dev/zero bs=1M count=64 of=test
> mkfs.ext4 -F test
> echo -n " " | dd of=test bs=1 count=1 seek=297195 conv=notrunc
> mount -o loop test /mnt/test
> dmesg -c
>
> On ubuntu natty with latest kernel, it seems, that
> fs/ext4/super.c:__save_error_info calls mod_timer before timer->function
> is set at end of fs/ext4/super.c:ext4_fill_super via
> sbi->s_err_report.function = print_daily_error_info;
>
> This causes BUG_ON(!timer->function) in kernel/timer.c:__mod_timer
> Device is stuck, not usable any more.
>
> Thanks
>
> - --
> http://www.halfdog.net/
> PGP: 156A AE98 B91F 0114 FE88 2BD8 C459 9386 feed a bee
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.6 (GNU/Linux)
>
> iD8DBQFN/cvFxFmThv7tq+4RAgfvAJ97N9bnKq4kN99XneTMyJZ5Hha9MQCfcguN
> L4trkTeOsIqDWF8m6VUqcgc=
> =zvYY
> -----END PGP SIGNATURE-----
> --
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---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

2011-06-20 01:42:23

by Theodore Ts'o

Subject: Re: Can someone confirm ext4 BUG_ON on latest kernel build?

On Sun, Jun 19, 2011 at 10:13:52AM +0000, halfdog wrote:
>
> Sorry, I do not have latest kernel. Can someone confirm this on latest?
> At least bugtracker does not know about it, and to my understanding of
> source, should be still here.
>
> dd if=/dev/zero bs=1M count=64 of=test
> mkfs.ext4 -F test
> echo -n " " | dd of=test bs=1 count=1 seek=297195 conv=notrunc
> mount -o loop test /mnt/test
> dmesg -c
>
> On ubuntu natty with latest kernel, it seems, that
> fs/ext4/super.c:__save_error_info calls mod_timer before timer->function
> is set at end of fs/ext4/super.c:ext4_fill_super via
> sbi->s_err_report.function = print_daily_error_info;
>
> This causes BUG_ON(!timer->function) in kernel/timer.c:__mod_timer
> Device is stuck, not usable any more.

This problem is fixed in 2.6.39 (via commit 0449641130f5, which landed
in mainline in 2.6.39-rc3).

Regards,

- Ted