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Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap |
Date: |
Thu, 9 Jul 2015 16:14:15 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
On 07/09/2015 03:59 PM, Paolo Bonzini wrote:
>
>
> On 09/07/2015 03:19, Wen Congyang wrote:
>> Yes, why migration doesn't trigger this problem? We will fix it soon.
>
> This should be the fix if someone wants to test it and/or post it:
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 57368e1..8d5a73a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1227,9 +1227,9 @@ static int ram_save_complete(QEMUFile *f, void
> *opaque)
>
> flush_compressed_data(f);
> ram_control_after_iterate(f, RAM_CONTROL_FINISH);
> - migration_end();
> -
> rcu_read_unlock();
> +
> + migration_end();
> qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
Yes, this patch can work. But if the caller hold the rcu read lock in
the future, we may need to fix it again. I think it is better to use
call_rcu().
>
> return 0;
>
>
> You don't see it with migration because the migration thread (and for
> that matter, _no_ thread except the I/O thread!) is not registered with
> the RCU subsystem. I'm working on it, but I plan to only fix it in
> later release candidates.
Thanks for the explantion.
Wen Congyang
>
> Paolo
>
- Re: [Qemu-devel] [PULL 24/28] migration: Make events a capability, (continued)
- [Qemu-devel] [PULL 25/28] migration: Add migration events on target side, Juan Quintela, 2015/07/07
- [Qemu-devel] [PULL 26/28] check_section_footers: Check the correct section_id, Juan Quintela, 2015/07/07
- [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Juan Quintela, 2015/07/07
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Kevin Wolf, 2015/07/08
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Paolo Bonzini, 2015/07/08
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Wen Congyang, 2015/07/08
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Paolo Bonzini, 2015/07/09
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap,
Wen Congyang <=
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Paolo Bonzini, 2015/07/09
- Re: [Qemu-devel] [PULL 27/28] migration: protect migration_bitmap, Wen Congyang, 2015/07/09
[Qemu-devel] [PULL 28/28] migration: extend migration_bitmap, Juan Quintela, 2015/07/07
Re: [Qemu-devel] [PULL v3 00/28] Migration pull request, Peter Maydell, 2015/07/07