Subject: Re: 2.6.30-rc6: Reported regressions from 2.6.29

From: Ingo Molnar <[email-masked]>
Date: Sun, 17 May 2009 09:33:27 +0200

* Rafael J. Wysocki <[email-masked]> wrote:

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13325
> Subject		: 2.6.30-rc kills my box hard - and lockdep chains
> Submitter	: Jonathan Corbet <[email-masked]>
> Date		: 2009-05-14 15:49 (3 days old)
> References	: http://marc.info/?l=linux-kernel&m=124231630701394&w=4

Jonathan, there's a side-issue reported there, us running out of 
lockdep space. Could you try this commit from -tip:

d80c19d: lockdep: increase MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS

(which i'll get to Linus in the next ~24 hours.) Maybe that allows 
lockdep to report the reason for the deadlock.

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13321
> Subject		: kernel crash with NULL pointer when boot
> Submitter	: Martin Bammer <[email-masked]>
> Date		: 2009-05-16 12:37 (1 days old)
> References	: http://lkml.org/lkml/2009/5/16/100

that crash is in reiserfs_for_each_xattr(), during sys_unlink()'s 
xattr teardown.

There's been a good deal of reiserfs changes in this cycle - some 
touch the xattr code as well. Some of them fairly late in the cycle, 
in the last two weeks:

 earth4:~/tip> gll v2.6.29..linus --since=two-weeks-ago fs/reiserfs/
 2a32ceb: Fix races around the access to ->s_options
 677c9b2: reiserfs: remove privroot hiding in lookup
 b82bb72: reiserfs: dont associate security.* with xattr files
 ab17c4f: reiserfs: fixup xattr_root caching
 edcc37a: Always lookup priv_root on reiserfs mount and keep it
 5a6059c: reiserfs: Expand i_mutex to enclose lookup_one_len

Martin, you could try a blind revert of say ... ab17c4f, which looks 
the most suspect and which is also a rather large commit.

Or/and you could try a bisect - perhaps accelerated via:

   git bisect start fs/reiserfs/

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13297
> Subject		: kernel panic -  not syncing : fatel exception in interupt
> Submitter	: rob <[email-masked]>
> Date		: 2009-05-12 19:34 (5 days old)
> References	: http://marc.info/?l=linux-kernel&m=124216126903309&w=4

tainted crash, but probably legit. It does show some badness in an 
old-IDE legacy codepath:

[<c0371865>] error_code+0x65/0x6c
[<c0110155>] do_page_fault+0x0/0x1e0
[<c027dafc>] ide_complete_rq+0xf/0x3b
[<c02870a0>] cdrom_newpc_intr+0x64d/0x6cd
[<c0286a53>] cdrom_newpc_intr+0x0/0x6cd
[<c027dcc2>] ide_intr+0x109/0x161
[<c0132298>] handle_IRQ_event+0x54/0xc7
[<c013354a>] handle_level_irq+0x4f/0x85
[<c0103df7>] handle_irq+0x17/0x20
[<c0103da5>] do_IRQ+0x2b/0x66
[<c0102be9>] common_interupt+0x29/0x30
[<c0480000>] cmd40x_init+0x2ac/0x38d
[<c0106db3>] default_idle+0x25/0x38
[<c01019be>] cpu_idle+0x19/0x2d
[<c0468907>] start_kernel+0x23f/0x242

report subject line is too unspecific, it should be changed to 
something like:

  legacy IDE cmd40x related bootup crash

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13296
> Subject		: Lockdep violation at cleanup_workqueue_thread during suspend
> Submitter	: Zdenek Kabelac <[email-masked]>
> Date		: 2009-05-12 7:59 (5 days old)
> References	: http://marc.info/?l=linux-kernel&m=124211522525625&w=4

looks like wireless related - the dependency that connects the 
locks in a wrong way appears to be:

 -> #2 (cfg80211_mutex){+.+.+.}:
        [<ffffffff80271a64>] __lock_acquire+0xc64/0x10a0
        [<ffffffff80271f38>] lock_acquire+0x98/0x140
        [<ffffffff8054e78c>] __mutex_lock_common+0x4c/0x3b0
        [<ffffffff8054ebf6>] mutex_lock_nested+0x46/0x60
        [<ffffffffa007e66a>] reg_todo+0x19a/0x590 [cfg80211]
        [<ffffffff80258f18>] worker_thread+0x1e8/0x3a0
        [<ffffffff8025dc3a>] kthread+0x5a/0xa0
        [<ffffffff8020d23a>] child_rip+0xa/0x20

(havent checked deeper)

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13245
> Subject		: possible circular locking dependency detected
> Submitter	: Miles Lane <[email-masked]>
> Date		: 2009-05-04 16:56 (13 days old)

same as #13296 above. (The one above should be merged into this one 
i guess)

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13126
> Subject		: BUG: MAX_LOCKDEP_ENTRIES too low! when mounting rootfs
> Submitter	: Alexander Beregalov <[email-masked]>
> Date		: 2009-04-15 12:43 (32 days old)
> References	: http://marc.info/?l=linux-kernel&m=123979949820538&w=4

should be resolved via the lockdep space extension fix.

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13118
> Subject		: iptables very slow after commit 784544739a25c30637397ace5489eeb6e15d7d49
> Submitter	: Jeff Chua <[email-masked]>
> Date		: 2009-04-10 16:05 (37 days old)
> References	: http://lkml.org/lkml/2009/4/10/111
> 		  http://lkml.org/lkml/2009/4/25/83
> Handled-By	: Eric Dumazet <[email-masked]>

solved by:

 commit 942e4a2bd680c606af0211e64eb216be2e19bf61
 Author: Stephen Hemminger <[email-masked]>
 Date:   Tue Apr 28 22:36:33 2009 -0700

    netfilter: revised locking for x_tables

commit log does not credit reporters and testers and does not 
mention bugzilla id.

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13116
> Subject		: Can't boot with nosmp
> Submitter	: Stephen Hemminger <[email-masked]>
> Date		: 2009-04-15 4:18 (32 days old)
> References	: http://marc.info/?l=linux-kernel&m=123976917817920&w=4
> Handled-By	: Dan Williams <[email-masked]>

I think this might be fixed by:

 d6de2c8: async: Fix module loading async-work regression

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13107
> Subject		: LTP 20080131 causes defunct processes w/2.6.30-rc1
> Submitter	: Kumar Gala <[email-masked]>
> Date		: 2009-04-09 15:43 (38 days old)
> First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b3bfa0cba867f23365b81658b47efd906830879b
> References	: http://marc.info/?l=linux-kernel&m=123929187208953&w=4
> 		  http://lkml.org/lkml/2009/4/10/193
> Handled-By	: Sukadev Bhattiprolu <[email-masked]>

Oleg says in that thread that it's as-designed, and followup 
questions were not replied to (yet).

But ... a relevant seeming commit has been bisected to so this 
shouldnt be ignored that easily.

Andrew, you merged the commit that was bisected to:

  From b3bfa0cba867f23365b81658b47efd906830879b Mon Sep 17 00:00:00 2001
  From: Sukadev Bhattiprolu <[email-masked]>
  Date: Thu, 2 Apr 2009 16:58:08 -0700
  Subject: [PATCH] signals: protect cinit from blocked fatal signals

> Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13068
> Subject		: Lockdep warining in inotify_dev_queue_event
> Submitter	: Sachin Sant <[email-masked]>
> Date		: 2009-04-05 12:37 (42 days old)
> References	: http://marc.info/?l=linux-kernel&m=123893439229272&w=4

should be fixed by:

381a80e: inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive

	Ingo