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Groups > linux.kernel > #1621953
| From | Borislav Petkov <bp@suse.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' |
| Date | 2017-04-12 11:20 +0200 |
| Message-ID | <tvmBs-2Gr-11@gated-at.bofh.it> (permalink) |
| References | <tvcLL-4GZ-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Apr 11, 2017 at 04:44:57PM -0600, Vishal Verma wrote:
> The NFIT MCE handler callback (for handling media errors on NVDIMMs)
> takes a mutex to add the location of a memory error to a list. But since
> the notifier call chain for machine checks (x86_mce_decoder_chain) is
> atomic, we get a lockdep splat like:
>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620
> in_atomic(): 1, irqs_disabled(): 0, pid: 4, name: kworker/0:0
> [..]
> Call Trace:
> dump_stack+0x86/0xc3
> ___might_sleep+0x178/0x240
> __might_sleep+0x4a/0x80
> mutex_lock_nested+0x43/0x3f0
> ? __lock_acquire+0xcbc/0x1290
> nfit_handle_mce+0x33/0x180 [nfit]
> notifier_call_chain+0x4a/0x70
> atomic_notifier_call_chain+0x6e/0x110
> ? atomic_notifier_call_chain+0x5/0x110
> mce_gen_pool_process+0x41/0x70
>
> Commit 648ed94038c030245a06e4be59744fd5cdc18c40
> x86/mce: Provide a lockless memory pool to save error records
> Changes the mce notifier callbacks to be run in a process context, and
> this can allow us to use the 'blocking' type notifier, where we can take
> mutexes etc. in the call chain functions.
>
> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
> arch/x86/kernel/cpu/mcheck/mce-genpool.c | 2 +-
> arch/x86/kernel/cpu/mcheck/mce-internal.h | 2 +-
> arch/x86/kernel/cpu/mcheck/mce.c | 8 ++++----
> 3 files changed, 6 insertions(+), 6 deletions(-)
>
> While this patch almost solves the problem, I think it is not quite right.
> The x86_mce_decoder_chain is also called from print_mce for fatal machine
> checks, and that is, afaict, still from an atomic context. One thing Tony
> suggested was splitting the notifier chain into two distinct chains, one
> for regular logging and recoverable actions that allows blocking, the
> other from the panic path.
Well, if Mohammad won't come to the mountain...
So the NFIT handler has:
/* We only care about memory errors */
if (!(mce->status & MCACOD))
return NOTIFY_DONE;
what severity are we talking here? Errors which can be reported on the
panic path, i.e., in atomic context or only AO/AR ones which don't raise
an #MC exception?
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
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[RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Vishal Verma <vishal.l.verma@intel.com> - 2017-04-12 00:50 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-12 11:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Vishal Verma <vishal.l.verma@intel.com> - 2017-04-12 22:10 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-12 22:30 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Verma, Vishal L" <vishal.l.verma@intel.com> - 2017-04-12 22:30 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Dan Williams <dan.j.williams@intel.com> - 2017-04-12 23:00 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 23:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Luck, Tony" <tony.luck@intel.com> - 2017-04-12 23:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-12 23:50 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-13 00:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Luck, Tony" <tony.luck@intel.com> - 2017-04-13 00:30 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-13 00:30 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-13 13:40 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-13 14:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Luck, Tony" <tony.luck@intel.com> - 2017-04-18 18:30 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Verma, Vishal L" <vishal.l.verma@intel.com> - 2017-04-21 23:50 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Luck, Tony" <tony.luck@intel.com> - 2017-04-12 23:00 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Borislav Petkov <bp@suse.de> - 2017-04-12 23:20 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 00:00 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 00:50 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 01:50 +0200
Re: [RFC PATCH] x86, mce: change the mce notifier to 'blocking' from 'atomic' "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 16:40 +0200
[tip:ras/urgent] x86/mce: Make the MCE notifier a blocking one tip-bot for Vishal Verma <tipbot@zytor.com> - 2017-04-18 22:30 +0200
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