From: Richard Weinberger <richard@nod.at>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>,
linux-um <linux-um@lists.infradead.org>
Subject: Re: [PATCH v6] um: Enable preemption in UML
Date: Fri, 22 Sep 2023 22:40:50 +0200 (CEST) [thread overview]
Message-ID: <1597650408.70670.1695415250057.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <389fbd9de31ccdaad52674b7de06312e57f2cd54.camel@sipsolutions.net>
----- Ursprüngliche Mail -----
> Von: "Johannes Berg" <johannes@sipsolutions.net>
>> - mmap_read_lock(mm);
>> + /* We use a RCU lock instead of a mm lock, because
>> + * this can be invoked out of critical/atomic sections
>> + * and that does not agree with the sleepable semantics
>> + * of the standard semaphore based mm lock.
>> + */
>> + rcu_read_lock();
>
> Yeah I guess ... Seems like a very mechanical description of what's
> going on, rather than a description of why this is correct (which
> assumes no preempt and no SMP)?
Is the VMA list actually RCU aware?
On UML we might get away with that, but I agree with Johannes, this needs a more
detailed explanation.
Thanks,
//richard
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next prev parent reply other threads:[~2023-09-22 20:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-22 10:56 [PATCH v6] um: Enable preemption in UML anton.ivanov
2023-09-22 10:56 ` Anton Ivanov
2023-09-22 11:22 ` Johannes Berg
2023-09-22 11:55 ` Anton Ivanov
2023-09-22 20:40 ` Richard Weinberger [this message]
2023-09-22 11:59 ` Peter Lafreniere
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