Re: [delayed_fput] BUG: unable to handle kernel paging request at ffff8800122a0ad0
From: Fengguang Wu
Date: Thu Jul 31 2014 - 06:27:32 EST
On Wed, Jul 30, 2014 at 07:53:15PM -0700, Alexei Starovoitov wrote:
> On Wed, Jul 30, 2014 at 7:40 PM, Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> > On Wed, Jul 30, 2014 at 04:00:58PM -0700, Alexei Starovoitov wrote:
> >> On Wed, Jul 30, 2014 at 3:51 PM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
> >> > On Wed, 30 Jul 2014, Christoph Hellwig wrote:
> >> >
> >> >> On Wed, Jul 30, 2014 at 11:55:41AM +0800, Fengguang Wu wrote:
> >> >> > Greetings,
> >> >> >
> >> >> > 0day kernel testing robot got the below dmesg and the first bad commit is
> >> >>
> >> >> How does this manage to trip over a 2 year old commit now?
> >>
> >> may be because all kernels are built with gcc 4.8.2 ?
> >> Fengguang, did you recently switch to new compiler?
> >> I think all older builds were with 4.6.3
> >
> > Alexei, I've been using gcc 4.8.2 for 4 months.
> >
> > Maybe it's because I test new randconfigs every day. And the problem
> > may only show up with very specific kernel config?
>
> It seems a lot of odd crashes suddenly showed up and I'm guessing it
> may be related to compiler...
> See commit 2062afb4f8 ("Fix gcc-4.9.0 miscompilation of load_balance()
> in scheduler")
> it's a nasty gcc bug that affects 4.9 and 4.8.
> I think it makes sense to apply that workaround before debugging much with 4.8
> just to eliminate the possibility of miscompiled code.
I tried boot testing 2062afb4f8~ and 2062afb4f8 with the same kernel
config. It looks make no much difference, at least for the problem in
this thread.
+-------------------------------------------------------------------------+------------+------------+
| | 8bdd638091 | 2062afb4f8 |
+-------------------------------------------------------------------------+------------+------------+
| boot_successes | 253 | 252 |
| boot_failures | 47 | 48 |
| BUG:kernel_boot_hang | 12 | 3 |
| BUG:unable_to_handle_kernel_paging_request | 10 | 15 |
| Oops | 12 | 17 |
| RIP:__fsnotify_update_child_dentry_flags | 2 | |
| Kernel_panic-not_syncing:Fatal_exception | 21 | 26 |
| backtrace:fsnotify_add_mark_locked | 3 | 1 |
| backtrace:SyS_inotify_add_watch | 3 | 1 |
| BUG:Bad_page_state_in_process | 10 | 17 |
| backtrace:cryptd_alloc_ablkcipher | 4 | 5 |
| backtrace:ablk_init_common | 4 | 5 |
| backtrace:ablk_init | 4 | 5 |
| backtrace:cryptomgr_test | 21 | 30 |
| BUG:spinlock_bad_magic_on_CPU | 3 | 4 |
| RIP:__d_lookup_rcu | 2 | |
| backtrace:do_sys_open | 1 | |
| backtrace:SyS_open | 1 | |
| backtrace:smpboot_thread_fn | 4 | 3 |
| general_protection_fault | 9 | 9 |
| RIP:crypto_ahash_setkey | 10 | 10 |
| RIP:kzfree | 6 | 13 |
| backtrace:vfs_stat | 2 | |
| backtrace:SyS_newstat | 2 | |
| WARNING:CPU:PID:at_kernel/sched/core.c:wake_up_process() | 1 | |
| BUG:unable_to_handle_kernel_NULL_pointer_dereference | 2 | 2 |
| backtrace:iterate_dir | 1 | 3 |
| backtrace:SyS_getdents | 1 | 3 |
| RIP:worker_thread | 1 | |
| Kernel_panic-not_syncing:VFS:Unable_to_mount_root_fs_on_unknown-block() | 1 | |
| backtrace:prepare_namespace | 1 | |
| backtrace:kernel_init_freeable | 1 | 2 |
| RIP:slob_page_alloc | 0 | 1 |
| backtrace:do_fork | 0 | 1 |
| backtrace:SyS_clone | 0 | 1 |
| backtrace:crypto_register_algs | 0 | 2 |
| backtrace:crypto_null_mod_init | 0 | 1 |
| backtrace:twofish_init | 0 | 1 |
| RIP:spin_dump | 0 | 1 |
| RIP:process_one_work | 0 | 1 |
+-------------------------------------------------------------------------+------------+------------+
Thanks,
Fengguang
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