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kerneloops.org: 2.6.26-rc possible regression in ext3

DISCUSSION Arjan van de Ven 6 participants 17 messages Jun 19, 2008

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#0 lore raw

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

but are generally of this pattern:

*do_split
ext3_add_entry
ext3_rename
vfs_rename
... <various paths into vfs_rename> ...

or

*do_split
? add_dirent_to_buf
ext3_add_entry
ext3_new_inode
ext3_add_nondir
ext3_create
vfs_create
....

did we change anything in ext

#2 lore raw
Quoted 5 lines · Dave Airlie
Quoted 4 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

Quoted 9 lines
Quoted 4 lines

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

This is a bug in rawhide in gcc miscompiling something...

https://bugzilla.redhat.com/show_bug.cgi?id=451068

thanks for letting us know so fast!
I've marked this one in the database as a fedora gcc bug

#4 lore raw
Quoted 8 lines · Linus Torvalds
Quoted 3 lines · Dave Airlie

This is a bug in rawhide in gcc miscompiling something...

https://bugzilla.redhat.com/show_bug.cgi?id=451068

Gaah. I should read all my email instead of wasting my time trying to match up the code with what I can reproduce..

unfortunately, kerneloops.org didn't pick up the link to this bug (due to the fact that the oops in the bug was a jpeg....)... maybe one day if I'm really bored I'll implement OCR into it ;)

sorry about wasting your time

#5 lore raw
In reply to Dave Airlie
Quoted 5 lines · Dave Airlie
Quoted 4 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

Quoted 7 lines
Quoted 3 lines

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

This is a bug in rawhide in gcc miscompiling something...

https://bugzilla.redhat.com/show_bug.cgi?id=451068

If I understand it correctly that's a bug in upstream gcc 4.3.1 (but not in gcc 4.3.0)?

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

Quoted 1 line

Dave.

cu
Adrian

Signature · 4 lines
       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed
#6 lore raw
Quoted 12 lines · Adrian Bunk
Quoted 11 lines · Dave Airlie
Quoted 7 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

This is a bug in rawhide in gcc miscompiling something...

Quoted 7 lines
Quoted 1 line

https://bugzilla.redhat.com/show_bug.cgi?id=451068

If I understand it correctly that's a bug in upstream gcc 4.3.1 (but not in gcc 4.3.0)?

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

There are other nasty bugs in gcc-4.3.0. I actually had to completely ban 4.3.0 in a user-space project I'm involved with (Erlang) due to gcc PR36339 (fixed in 4.3.1).

What's the gcc bugzilla number for this new 4.3.1 bug?

#7 lore raw
Quoted 2 lines · Mikael Pettersson

...
What's the gcc bugzilla number for this new 4.3.1 bug?

#36533

cu
Adrian

Signature · 4 lines
       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed
#8 lore raw
In reply to Adrian Bunk
Quoted 4 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

#9 lore raw
Quoted 7 lines · Arjan van de Ven
Quoted 3 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

The gcc Bugzilla contains a testcase.

But how do you plan to integrate it into a kernel build?

cu
Adrian

Signature · 4 lines
       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed
#10 lore raw
Quoted 10 lines · Adrian Bunk
Quoted 5 lines · Arjan van de Ven
Quoted 2 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

The gcc Bugzilla contains a testcase.

But how do you plan to integrate it into a kernel build?

we already have several of these.
Just look at scripts/gcc-x86_64-has-stack-protector.sh for an example of such a beast.

#11 lore raw
Quoted 8 lines · Arjan van de Ven
Quoted 7 lines · Adrian Bunk
Quoted 5 lines · Arjan van de Ven
Quoted 2 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

Quoted 6 lines
Quoted 3 lines

The gcc Bugzilla contains a testcase.

But how do you plan to integrate it into a kernel build?

we already have several of these.
Just look at scripts/gcc-x86_64-has-stack-protector.sh for an example of such a beast.

Checking whether gcc supports some flags is easy.

But miscompilations are a different issue.

Especially since we also want to reject broken gcc versions for cross compilations.

cu
Adrian

Signature · 4 lines
       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed
#12 lore raw
Quoted 8 lines · Adrian Bunk
Quoted 7 lines · Arjan van de Ven
Quoted 6 lines · Adrian Bunk
Quoted 5 lines · Arjan van de Ven
Quoted 2 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

Quoted 7 lines
Quoted 5 lines
Quoted 3 lines

The gcc Bugzilla contains a testcase.

But how do you plan to integrate it into a kernel build?

we already have several of these.
Just look at scripts/gcc-x86_64-has-stack-protector.sh for an example of such a beast.

Checking whether gcc supports some flags is easy.

have you actually looked at this script?
You didn't, since the script doesn't check if gcc supports some flag. It checks very specifically for a code generation pattern...

Please go look at the script first before responding.

#13 lore raw
Quoted 15 lines · Arjan van de Ven
Quoted 14 lines · Adrian Bunk
Quoted 12 lines · Arjan van de Ven
Quoted 9 lines · Adrian Bunk
Quoted 5 lines · Arjan van de Ven
Quoted 2 lines · Adrian Bunk

Expect a lot more of this to pop up in the future. Should we #error for gcc 4.3.1?

it/s better to find if the gcc guys made a testcase for this bug (they normally do) and test based on that.

The gcc Bugzilla contains a testcase.

But how do you plan to integrate it into a kernel build?

we already have several of these.
Just look at scripts/gcc-x86_64-has-stack-protector.sh for an example of such a beast.

Quoted 7 lines
Quoted 1 line

Checking whether gcc supports some flags is easy.

have you actually looked at this script?
You didn't, since the script doesn't check if gcc supports some flag. It checks very specifically for a code generation pattern...

Please go look at the script first before responding.

I did look, but I missed the last pipe...

Do we know for sure this bug can only trigger on 32bit x86?

Or is there anything else I miss in gcc-x86_64-has-stack-protector.sh that allows to use this approach to check for wrong code generation caused by platform independent gcc bugs?

cu
Adrian

Signature · 4 lines
       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed
#14 lore raw
In reply to Arjan van de Ven
Quoted 7 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

Arjan, I was just looking at kerneloops last night, seeing the count for this oops climb, and was wishing there were some way to annotate an oops signature with more info. If I could have tagged this with the RH bugzilla nr. it might have saved a lot of time for folks. Is this feasible? Or is finding the oops text in bugzilla the only way?

Thanks,

-Eric

#15 lore raw
Quoted 7 lines · Eric Sandeen
Quoted 6 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

It happens with various applications; the backtraces are at:

Quoted 8 lines
Quoted 1 line

http://www.kerneloops.org/search.php?search=do_split

Arjan, I was just looking at kerneloops last night, seeing the count for this oops climb, and was wishing there were some way to annotate an oops signature with more info. If I could have tagged this with the RH bugzilla nr. it might have saved a lot of time for folks. Is this feasible? Or is finding the oops text in bugzilla the only way?

there's a way to add a description to oopses (you might have seen some of these descriptions already); however I've not implemented an account system yet so for now it's only me who can add these.

#16 lore raw
Quoted 16 lines · Arjan van de Ven
Quoted 5 lines · Eric Sandeen
Quoted 4 lines · Arjan van de Ven

In the kerneloops.org stats, a new oops is rapidly climbing the charts. The oops is a page fault in the ext3 "do_slit" function, and the first report of it was with 2.6.26-rc6-git3.

Quoted 9 lines
Quoted 3 lines

It happens with various applications; the backtraces are at:

http://www.kerneloops.org/search.php?search=do_split

Arjan, I was just looking at kerneloops last night, seeing the count for this oops climb, and was wishing there were some way to annotate an oops signature with more info. If I could have tagged this with the RH bugzilla nr. it might have saved a lot of time for folks. Is this feasible? Or is finding the oops text in bugzilla the only way?

Quoted 3 lines

there's a way to add a description to oopses (you might have seen some of these descriptions already); however I've not implemented an account system yet so for now it's only me who can add these.

Ok, that was my guess. I'll shoot you an email next time. :)

Thanks,
-Eric