From: "Naik, Avadhut" <avadnaik@amd.com>
To: "Luck, Tony" <tony.luck@intel.com>,
Yazen Ghannam <yazen.ghannam@amd.com>,
Borislav Petkov <bp@alien8.de>
Cc: "Mehta, Sohil" <sohil.mehta@intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Avadhut Naik <avadhut.naik@amd.com>
Subject: [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool
Date: Mon, 12 Feb 2024 13:40:21 -0600 [thread overview]
Message-ID: <1cf19ecf-4785-48c9-91ef-4ca3c965f568@amd.com> (raw)
In-Reply-To: <SJ1PR11MB6083CF3400AD2F2047D65E17FC482@SJ1PR11MB6083.namprd11.prod.outlook.com>
Hi,
On 2/12/2024 12:58, Luck, Tony wrote:
>> I need to look more at the genpool code, but I thought I'd ask too.
>
> Yazen,
>
> gen_pool_add_owner() is the code that adds an extra chunk to an existing genpool.
>
> This bit doesn't look obviously safe against a #MC at the wrong moment in the middle of
> the list_add_rcu()
>
> spin_lock(&pool->lock);
> list_add_rcu(&chunk->next_chunk, &pool->chunks);
> spin_unlock(&pool->lock);
>
Even I am somewhat confused by this.
The spinlock is mostly held to prevent other primitives
from modifying chunks within the genpool.
In #MC context however, we are not modifying the existing
chunks, per se.
While in the MC context, records will be added to the genpool
through gen_pool_alloc() which eventually drops down into
gen_pool_alloc_algo_owner().
gen_pool_alloc_algo_owner() iterates over the existing chunks
within the genpool through list_for_each_entry_rcu(), within
an RCU read-side critical section (rcu_read_lock()).
Now, the below description of list_for_each_entry_rcu():
* list_for_each_entry_rcu - iterate over rcu list of given type
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.
* @member: the name of the list_head within the struct.
* @cond: optional lockdep expression if called from non-RCU protection.
*
* This list-traversal primitive may safely run concurrently with
* the _rcu list-mutation primitives such as list_add_rcu()
* as long as the traversal is guarded by rcu_read_lock().
Makes me wonder if the genpool can be extended and traversed
concurrently.
OFC, not sure if gen_pool_alloc_algo_owner() being in #MC context
makes a difference here or if I am missing something.
--
Thanks,
Avadhut Naik
> -Tony
>
>
>
>
next prev parent reply other threads:[~2024-02-12 19:40 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 22:56 [PATCH 0/2] Extend size of the MCE Records pool Avadhut Naik
2024-02-07 22:56 ` [PATCH 1/2] x86/MCE: " Avadhut Naik
2024-02-08 0:02 ` Luck, Tony
2024-02-08 17:41 ` Naik, Avadhut
2024-02-08 17:47 ` Naik, Avadhut
2024-02-08 18:39 ` Luck, Tony
2024-02-09 19:47 ` Naik, Avadhut
2024-02-08 21:09 ` Sohil Mehta
2024-02-09 19:52 ` Naik, Avadhut
2024-02-07 22:56 ` [PATCH 2/2] x86/MCE: Add command line option to extend " Avadhut Naik
2024-02-09 1:36 ` Sohil Mehta
2024-02-09 20:02 ` Naik, Avadhut
2024-02-09 20:09 ` Borislav Petkov
2024-02-09 20:35 ` Naik, Avadhut
2024-02-09 20:51 ` Borislav Petkov
2024-02-10 7:52 ` Borislav Petkov
2024-02-10 21:15 ` Naik, Avadhut
2024-02-11 11:14 ` Borislav Petkov
2024-02-12 2:54 ` Naik, Avadhut
2024-02-12 8:58 ` Borislav Petkov
2024-02-12 9:32 ` Borislav Petkov
2024-02-12 17:29 ` Luck, Tony
2024-02-12 17:54 ` Borislav Petkov
2024-02-12 18:45 ` Luck, Tony
2024-02-12 19:14 ` Borislav Petkov
2024-02-12 19:41 ` Luck, Tony
2024-02-12 21:37 ` Tony Luck
2024-02-12 22:08 ` Borislav Petkov
2024-02-12 22:19 ` Borislav Petkov
2024-02-12 22:42 ` Borislav Petkov
2024-02-28 23:14 ` [PATCH] x86/mce: Dynamically size space for machine check records Tony Luck
2024-02-29 0:39 ` Sohil Mehta
2024-02-29 0:44 ` Luck, Tony
2024-02-29 1:56 ` Sohil Mehta
2024-02-29 15:49 ` Yazen Ghannam
2024-02-29 17:22 ` Tony Luck
2024-02-29 17:21 ` Tony Luck
2024-02-29 23:56 ` Sohil Mehta
2024-02-29 6:42 ` Naik, Avadhut
2024-02-29 8:39 ` Borislav Petkov
2024-02-29 17:47 ` Tony Luck
2024-02-29 18:28 ` Naik, Avadhut
2024-02-29 18:38 ` Luck, Tony
2024-02-29 17:26 ` Tony Luck
2024-03-06 21:52 ` Naik, Avadhut
2024-03-06 22:07 ` Luck, Tony
2024-03-06 23:21 ` Naik, Avadhut
2024-02-15 20:18 ` [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool Naik, Avadhut
2024-02-15 20:15 ` Naik, Avadhut
2024-02-15 20:14 ` Naik, Avadhut
2024-02-12 18:47 ` Yazen Ghannam
2024-02-12 18:58 ` Luck, Tony
2024-02-12 19:40 ` Naik, Avadhut [this message]
2024-02-12 20:18 ` Borislav Petkov
2024-02-12 20:51 ` Naik, Avadhut
2024-02-12 19:43 ` Yazen Ghannam
2024-02-12 19:49 ` Luck, Tony
2024-02-12 20:10 ` Borislav Petkov
2024-02-12 20:44 ` Paul E. McKenney
2024-02-12 21:18 ` Luck, Tony
2024-02-12 21:27 ` Borislav Petkov
2024-02-12 22:46 ` Paul E. McKenney
2024-02-12 22:53 ` Luck, Tony
2024-02-12 23:10 ` Borislav Petkov
2024-02-13 1:07 ` Paul E. McKenney
2024-02-09 20:16 ` Sohil Mehta
2024-02-09 20:28 ` Luck, Tony
2024-02-09 21:02 ` Sohil Mehta
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