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[184.144.111.238]) by smtp.gmail.com with ESMTPSA id v15sm1430976qkp.96.2021.07.08.12.06.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jul 2021 12:06:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625771223; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qoGIaSSybi+Tx59880HHNpG+HkBjifrEItBdgQov8Zc=; b=b5YBJXc/OcvCSY0VlGXYYfvK/YY+mterC9No2hlm/z2R0ghURX1jna2Mokz5FpYZeEvaaB RWfLPFPpBICF+CDjuvwzTLb3rcj46Vi5phl01FZ0IUH35ZEFUE6qrjcfy9ELtZwn88pfYJ sjYUAvAqBCj5APEwjeMKYTIxF9a16y4= X-MC-Unique: Aiq9KeofN_G88bXKFVryXA-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=qoGIaSSybi+Tx59880HHNpG+HkBjifrEItBdgQov8Zc=; b=FNMuIzpQLrZxgj9cCI5Y5sztHX5IQYt75AwklAOubimzJykS9JxeN4/aEylUVT3uDm L2OQl8m0HivK0ehQrv7/XK0UZnUqjc/s+ol5W24vwCJNatYX3+PHZQItYyYNEMVbhkZo N0taP1YXhpj5/Mpf+lYoK3hg3XEXsp8AS892yWREDUb7CwVD9pONQrm0+7BLqycI/8Tv nZ4H3WmdUDPnp5ekSbxo4jy5+QVaCVhyBuT+gypDfmAjPgm8FBeqx9nE1oMENhN7mThi qSaq8p+UhMrfwsd+hBLk6MJcdyA/ojXj31HD/aRMN6A0tm1Oo7HAh4jIcHtxPrIYfjaZ +oCQ== X-Gm-Message-State: AOAM530splWDRbd5dyK18q1PL3sPI5DjkXfqum8LKP6tYqXQrgp8c8q5 Xa3Dq6VDvyeN6Bo2i+CXMIcW8bFCYXtUbMJ0MOBbvO9MHDr9w53InkuoUQugkp0a8kBZszo4WnI DKaml7noXU4igmxaKkkoT8jmTtFmg0Heuu/e/cgQ48b4tfZu7/cRyhX1hm/V3koJA X-Received: by 2002:a0c:d68f:: with SMTP id k15mr31602885qvi.14.1625771219261; Thu, 08 Jul 2021 12:06:59 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy9MixROmqxryFMKlkfBrq/qrsoYCiuPw+Vfu3jp6rSeUPNDTDbuyEFYQNyF2+6MXS8FA8yyQ== X-Received: by 2002:a0c:d68f:: with SMTP id k15mr31602854qvi.14.1625771218970; Thu, 08 Jul 2021 12:06:58 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Subject: [PATCH 1/3] migration: Release return path early for paused postcopy Date: Thu, 8 Jul 2021 15:06:51 -0400 Message-Id: <20210708190653.252961-2-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210708190653.252961-1-peterx@redhat.com> References: <20210708190653.252961-1-peterx@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.45, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lukas Straub , Juan Quintela , Li Xiaohui , "Dr . David Alan Gilbert" , peterx@redhat.com, Li Xiaohui , Leonardo Bras Soares Passos Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1625771563939100001 Content-Type: text/plain; charset="utf-8" When postcopy pause triggered, we rely on the migration thread to cleanup t= he to_dst_file handle, and the return path thread to cleanup the from_dst_file handle (which is stored in the local variable "rp"). Within the process, from_dst_file cleanup (qemu_fclose) is postponed until = it's setup again due to a postcopy recovery. It used to work before yank was born; after yank is introduced we rely on t= he refcount of IOC to correctly unregister yank function in channel_close(). = If without the early and on-time release of from_dst_file handle the yank func= tion will be leftover during paused postcopy. Without this patch, below steps (quoted from Xiaohui) could trigger qemu src crash: 1.Boot vm on src host 2.Boot vm on dst host 3.Enable postcopy on src&dst host 4.Load stressapptest in vm and set postcopy speed to 50M 5.Start migration from src to dst host, change into postcopy mode when mi= gration is active. 6.When postcopy is active, down the network card(do migration via this ne= twork) on dst host. 7.Wait untill postcopy is paused on src&dst host. 8.Before up network card, recover migration on dst host, will get error l= ike following. 9.Ignore the error of step 8, go on recovering migration on src host: After step 9, qemu on src host will core dump after some seconds: qemu-kvm: ../util/yank.c:107: yank_unregister_instance: Assertion `QLIST_= EMPTY(&entry->yankfns)' failed. 1.sh: line 38: 44662 Aborted (core dumped) Reported-by: Li Xiaohui Signed-off-by: Peter Xu --- migration/migration.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 5ff7ba9d5c..8786104c9a 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2818,12 +2818,12 @@ out: * Maybe there is something we can do: it looks like a * network down issue, and we pause for a recovery. */ + qemu_fclose(rp); + ms->rp_state.from_dst_file =3D NULL; + rp =3D NULL; if (postcopy_pause_return_path_thread(ms)) { /* Reload rp, reset the rest */ - if (rp !=3D ms->rp_state.from_dst_file) { - qemu_fclose(rp); - rp =3D ms->rp_state.from_dst_file; - } + rp =3D ms->rp_state.from_dst_file; ms->rp_state.error =3D false; goto retry; } --=20 2.31.1