From: Paolo Bonzini <pbonzini@redhat.com>
To: Andrea Arcangeli <aarcange@redhat.com>, Oleg Nesterov <oleg@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
Avi Kivity <avi.kivity@gmail.com>, Gleb Natapov <gleb@kernel.org>,
Dominik Dingel <dingel@linux.vnet.ibm.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: async_pf: kill the unnecessary use_mm/unuse_mm async_pf_execute()
Date: Mon, 28 Apr 2014 17:31:22 +0200 [thread overview]
Message-ID: <535E744A.1060708@redhat.com> (raw)
In-Reply-To: <20140428140602.GC10488@redhat.com>
Il 28/04/2014 16:06, Andrea Arcangeli ha scritto:
>> >
>> > "task" is only used to increment task_struct->xxx_flt. I don't think
>> > async_pf_execute() actually needs this (current is PF_WQ_WORKER after
>> > all), but I didn't dare to do another change in the code I can hardly
>> > understand.
> Considering the faults would be randomly distributed among the kworker
> threads my preference would also be for NULL instead of current.
>
> ptrace and uprobes tends to be the only two places that look into
> other mm with gup, ptrace knows the exact pid that it is triggering
> the fault into, so it also can specify the correct task so the fault
> goes in the right task struct. uprobes uses NULL.
KVM knows the correct task (it was in current when kvm_create_vm was
called), and doing accounting right would be nice. But I agree that
NULL is less misleading than a dummy current, and I applied patch 3 too.
Paolo
next prev parent reply other threads:[~2014-04-28 15:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-21 13:25 [PATCH 0/2] KVM: async_pf: use_mm/mm_users fixes Oleg Nesterov
2014-04-21 13:25 ` [PATCH 1/2] KVM: async_pf: kill the unnecessary use_mm/unuse_mm async_pf_execute() Oleg Nesterov
2014-04-22 20:15 ` Christian Borntraeger
2014-04-22 21:07 ` Christian Borntraeger
2014-04-23 19:32 ` Oleg Nesterov
2014-04-28 14:06 ` Andrea Arcangeli
2014-04-28 15:31 ` Paolo Bonzini [this message]
2014-04-21 13:26 ` [PATCH 2/2] KVM: async_pf: mm->mm_users can not pin apf->mm Oleg Nesterov
2014-04-22 20:24 ` Christian Borntraeger
2014-04-24 14:27 ` [PATCH 0/2] KVM: async_pf: use_mm/mm_users fixes Christian Borntraeger
2014-04-24 14:55 ` Oleg Nesterov
2014-04-28 11:06 ` Paolo Bonzini
2014-04-28 14:15 ` Andrea Arcangeli
2014-04-28 15:02 ` [PATCH 3/2] KVM: async_pf: change async_pf_execute() to use get_user_pages(tsk => NULL) Oleg Nesterov
2014-04-28 15:03 ` Oleg Nesterov
2014-04-28 15:27 ` Paolo Bonzini
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