26a68c032e
migration: bugfix, multifd send pages next channel and Make sure that we do not call write in case Signed-off-by: imxcc <xingchaochao@huawei.com>
51 lines
1.9 KiB
Diff
51 lines
1.9 KiB
Diff
From c11a23b92334ae86eddfdc2b155d404293891985 Mon Sep 17 00:00:00 2001
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From: alexchen <alex.chen@huawei.com>
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Date: Tue, 8 Sep 2020 11:18:50 +0000
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Subject: [PATCH 08/11] migration: fix multifd_send_pages() next channel
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multifd_send_pages() loops around the available channels,
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the next channel to use between two calls to multifd_send_pages() is stored
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inside a local static variable, next_channel.
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It works well, except if the number of channels decreases between two calls
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to multifd_send_pages(). In this case, the loop can try to access the
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data of a channel that doesn't exist anymore.
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The problem can be triggered if we start a migration with a given number of
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channels and then we cancel the migration to restart it with a lower number.
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This ends generally with an error like:
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qemu-system-ppc64: .../util/qemu-thread-posix.c:77: qemu_mutex_lock_impl: Assertion `mutex->initialized' failed.
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This patch fixes the error by capping next_channel with the current number
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of channels before using it.
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Signed-off-by: Laurent Vivier <lvivier@redhat.com>
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Message-Id: <20200617113154.593233-1-lvivier@redhat.com>
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Reviewed-by: Juan Quintela <quintela@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: BiaoXiang Ye <yebiaoxiang@huawei.com>
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---
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migration/ram.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/migration/ram.c b/migration/ram.c
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index 83cabec6..ac033f22 100644
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--- a/migration/ram.c
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+++ b/migration/ram.c
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@@ -931,6 +931,12 @@ static int multifd_send_pages(RAMState *rs)
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uint64_t transferred;
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qemu_sem_wait(&multifd_send_state->channels_ready);
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+ /*
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+ * next_channel can remain from a previous migration that was
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+ * using more channels, so ensure it doesn't overflow if the
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+ * limit is lower now.
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+ */
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+ next_channel %= migrate_multifd_channels();
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for (i = next_channel;; i = (i + 1) % migrate_multifd_channels()) {
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p = &multifd_send_state->params[i];
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--
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2.27.0.dirty
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