From: Juan Quintela <quintela@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Shameerali Kolothum Thodi"
<shameerali.kolothum.thodi@huawei.com>,
qemu-devel@nongnu.org, "Shannon Zhao" <shannon.zhao@linaro.org>,
"Igor Mammedov" <imammedo@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [PATCH RFC] memory: Don't allow to resize RAM while migrating
Date: Fri, 14 Feb 2020 13:46:50 +0100 [thread overview]
Message-ID: <87k14pgwud.fsf@secure.laptop> (raw)
In-Reply-To: <bb33b209-2b15-4bbd-7fe9-3aa813e4c194@redhat.com> (David Hildenbrand's message of "Fri, 14 Feb 2020 13:02:46 +0100")
David Hildenbrand <david@redhat.com> wrote:
I agree with the removed bits.
> diff --git a/migration/ram.c b/migration/ram.c
> index ed23ed1c7c..f86f32b453 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -52,6 +52,7 @@
> #include "migration/colo.h"
> #include "block.h"
> #include "sysemu/sysemu.h"
> +#include "sysemu/runstate.h"
> #include "savevm.h"
> #include "qemu/iov.h"
> #include "multifd.h"
> @@ -3710,8 +3711,49 @@ static SaveVMHandlers savevm_ram_handlers = {
> .resume_prepare = ram_resume_prepare,
> };
>
> +static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,
> + size_t old_size, size_t new_size)
> +{
> + /*
> + * We don't care about resizes triggered on incoming migration (when
> + * syncing ram blocks), or of course, when no migration is going on.
> + */
> + if (migration_is_idle() || !runstate_is_running()) {
> + return;
> + }
> +
> + if (!postcopy_is_running()) {
> + Error *err = NULL;
> +
> + /*
> + * Precopy code cannot deal with the size of ram blocks changing at
> + * random points in time. We're still running on the source, abort
> + * the migration and continue running here. Make sure to wait until
> + * migration was canceled.
> + */
> + error_setg(&err, "RAM resized during precopy.");
> + migrate_set_error(migrate_get_current(), err);
> + error_free(err);
> + migration_cancel();
If we can't do anything else, this is reasonable.
But as discussed before, it is still not fully clear to me _why_ are
ramblocks changing if we have disabled add/remove memory during migration.
> + } else {
> + /*
> + * Postcopy code cannot deal with the size of ram blocks changing at
> + * random points in time. We're running on the target. Fail hard.
> + *
> + * TODO: How to handle this in a better way?
> + */
> + error_report("RAM resized during postcopy.");
> + exit(-1);
Idea is good, but we also need to exit destination, not only source, no?
> + }
> +}
> +static RAMBlockNotifier ram_mig_ram_notifier = {
> + .ram_block_resized = ram_mig_ram_block_resized,
> +};
> +
> void ram_mig_init(void)
> {
> qemu_mutex_init(&XBZRLE.lock);
> register_savevm_live("ram", 0, 4, &savevm_ram_handlers, &ram_state);
> + ram_block_notifier_add(&ram_mig_ram_notifier);
> }
Shouldn't we remove the notifier when we finish the migration.
Later, Juan.
next prev parent reply other threads:[~2020-02-14 12:48 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 17:20 [PATCH RFC] memory: Don't allow to resize RAM while migrating David Hildenbrand
2020-02-13 18:32 ` Peter Xu
2020-02-13 19:42 ` David Hildenbrand
2020-02-13 20:56 ` Peter Xu
2020-02-14 9:17 ` David Hildenbrand
2020-02-14 15:56 ` Peter Xu
2020-02-14 16:45 ` David Hildenbrand
2020-02-13 19:09 ` Juan Quintela
2020-02-13 19:38 ` David Hildenbrand
2020-02-14 10:25 ` Dr. David Alan Gilbert
2020-02-14 10:32 ` David Hildenbrand
2020-02-14 10:42 ` Dr. David Alan Gilbert
2020-02-14 10:46 ` David Hildenbrand
2020-02-14 11:02 ` Dr. David Alan Gilbert
2020-02-14 11:08 ` David Hildenbrand
2020-02-14 12:02 ` David Hildenbrand
2020-02-14 12:46 ` Juan Quintela [this message]
2020-02-14 14:00 ` David Hildenbrand
2020-02-14 15:14 ` Dr. David Alan Gilbert
2020-02-14 17:29 ` Peter Xu
2020-02-14 17:32 ` David Hildenbrand
2020-02-14 18:11 ` Peter Xu
2020-02-14 18:26 ` David Hildenbrand
2020-02-14 19:44 ` Peter Xu
2020-02-14 20:04 ` David Hildenbrand
2020-02-14 20:38 ` Peter Xu
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