From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7E6C10F1 for ; Wed, 22 Jun 2022 03:22:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655868138; 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: in-reply-to:in-reply-to:references:references; bh=SnmpFslx4bnuHaAyB7sYVJCt/WlKAGOw6+XqvSCoZx0=; b=Gfun1pu9kPlbA3VKESUlXU4yvkjxDfHHIXp6oLHFnB3o1PQw1E217T3/wGOgYqm8sbb4Ik XXOJiyWFbgoj12jxwqXOyt+6nj2RsNqGLimmsKlmcTofnJY8fWfBcCHCPS8Nayp995pqFP Rf8cKgQFxlkgOcYIKtYV7jMY1kdZcsc= Received: from mail-lf1-f72.google.com (mail-lf1-f72.google.com [209.85.167.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-331-Sj6M5_XUOxmg8qPGThCw6g-1; Tue, 21 Jun 2022 23:22:14 -0400 X-MC-Unique: Sj6M5_XUOxmg8qPGThCw6g-1 Received: by mail-lf1-f72.google.com with SMTP id bq4-20020a056512150400b0047f7f36efc6so1814540lfb.9 for ; Tue, 21 Jun 2022 20:22:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SnmpFslx4bnuHaAyB7sYVJCt/WlKAGOw6+XqvSCoZx0=; b=zTGScU3nB+97Q6MnUthgfexW5/3NLu26902tkUaTYo7fRVmKfFmieb7LbGvkd0K7yE 79BwyWhuCzeDAARWbZxnHo2iMul4cQ6PUW7DfpvYeJZh+06BPirNf3ambmaMlKW2E1jV zmUgGtN5wJ1yj1Os+5QF1prYKntLTRqR5DTFuj4rGIS/Xi5vtMbhZrig9gHEi3XbDk75 Hzl5LbJtM/k1uqDuq5Ol3IHPW+XfU8K9PL0HjkRZNdo0Rv6sr/DH/JpMTpfxlWcH3Zrz FrGiYk8r/8KFRI493Dud3t1Cszmx7B9TAWhsjkz7ukLjn97ZaWfZWMykKO5ExDUTmnSI Z/AQ== X-Gm-Message-State: AJIora9uqtrkNiIHnYlJzugxBTSoOilRgjPjle/JucPbS3Xl/YoJJZy7 hcEAsnGKgckYgVE+OktvJg8ou+Y+vCCjRQHH1z2itHxVRLmmFFfLLfmWnxFqpR3BBjf/pvKIiec Q2f1dBE/uybhr9LBdfDjXt61erILZJfO7 X-Received: by 2002:a2e:8417:0:b0:25a:7fa7:fe5a with SMTP id z23-20020a2e8417000000b0025a7fa7fe5amr653195ljg.323.1655868132145; Tue, 21 Jun 2022 20:22:12 -0700 (PDT) X-Google-Smtp-Source: AGRyM1t/frWZNRtk8L3UkGe4WAgj478I0gEjlb7eeqzCxUDALH57QzdbpZAt++HRXXwuzU4w0RUbdsijdH1hKiE+NG8= X-Received: by 2002:a2e:8417:0:b0:25a:7fa7:fe5a with SMTP id z23-20020a2e8417000000b0025a7fa7fe5amr653187ljg.323.1655868131933; Tue, 21 Jun 2022 20:22:11 -0700 (PDT) Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20220620081519.1494-1-jasowang@redhat.com> <62b2476ca8c21_892072947a@dwillia2-xfh.notmuch> In-Reply-To: <62b2476ca8c21_892072947a@dwillia2-xfh.notmuch> From: Jason Wang Date: Wed, 22 Jun 2022 11:22:00 +0800 Message-ID: Subject: Re: [PATCH 1/2] virtio_pmem: initialize provider_data through nd_region_desc To: Dan Williams Cc: vishal.l.verma@intel.com, "Jiang, Dave" , ira.weiny@intel.com, nvdimm@lists.linux.dev, mst Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" On Wed, Jun 22, 2022 at 6:34 AM Dan Williams wrote: > > Jason Wang wrote: > > We used to initialize the provider_data manually after > > nvdimm_pemm_region_create(). This seems to be racy if the flush is > > It would be nice to include the actual backtrace / bug signature that > this fixes if it is available. The bug was spotted during code review. But it can be reproduced by adding a msleep() between nvdimm_pmem_region_create() and nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c index 995b6cdc67ed..153d9dbfbe70 100644 --- a/drivers/nvdimm/virtio_pmem.c +++ b/drivers/nvdimm/virtio_pmem.c @@ -8,6 +8,7 @@ */ #include "virtio_pmem.h" #include "nd.h" +#include static struct virtio_device_id id_table[] = { { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, @@ -89,6 +90,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev) err = -ENXIO; goto out_nd; } + msleep(100 * 1000); nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); return 0; out_nd: Then if we hotplug and try to do mkfs we get: [ 80.152281] nd_pmem namespace0.0: unable to guarantee persistence of writes [ 92.393956] BUG: kernel NULL pointer dereference, address: 0000000000000318 [ 92.394551] #PF: supervisor read access in kernel mode [ 92.394955] #PF: error_code(0x0000) - not-present page [ 92.395365] PGD 0 P4D 0 [ 92.395566] Oops: 0000 [#1] PREEMPT SMP PTI [ 92.395867] CPU: 2 PID: 506 Comm: mkfs.ext4 Not tainted 5.19.0-rc1+ #453 [ 92.396365] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 [ 92.397178] RIP: 0010:virtio_pmem_flush+0x2f/0x1f0 [ 92.397521] Code: 55 41 54 55 53 48 81 ec a0 00 00 00 65 48 8b 04 25 28 00 00 00 48 89 84 24 98 00 00 00 31 c0 48 8b 87 78 03 00 00 48 89 04 24 <48> 8b 98 18 03 00 00 e8 85 bf 6b 00 ba 58 00 00 00 be c0 0c 00 00 [ 92.398982] RSP: 0018:ffff9a7380aefc88 EFLAGS: 00010246 [ 92.399349] RAX: 0000000000000000 RBX: ffff8e77c3f86f00 RCX: 0000000000000000 [ 92.399833] RDX: ffffffffad4ea720 RSI: ffff8e77c41e39c0 RDI: ffff8e77c41c5c00 [ 92.400388] RBP: ffff8e77c41e39c0 R08: ffff8e77c19f0600 R09: 0000000000000000 [ 92.400874] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8e77c0814e28 [ 92.401364] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8e77c41e39c0 [ 92.401849] FS: 00007f3cd75b2780(0000) GS:ffff8e7937d00000(0000) knlGS:0000000000000000 [ 92.402423] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 92.402821] CR2: 0000000000000318 CR3: 0000000103c80002 CR4: 0000000000370ee0 [ 92.403307] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 92.403793] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 92.404278] Call Trace: [ 92.404481] [ 92.404654] ? mempool_alloc+0x5d/0x160 [ 92.404939] ? terminate_walk+0x5f/0xf0 [ 92.405226] ? bio_alloc_bioset+0xbb/0x3f0 [ 92.405525] async_pmem_flush+0x17/0x80 [ 92.405806] nvdimm_flush+0x11/0x30 [ 92.406067] pmem_submit_bio+0x1e9/0x200 [ 92.406354] __submit_bio+0x80/0x120 [ 92.406621] submit_bio_noacct_nocheck+0xdc/0x2a0 [ 92.406958] submit_bio_wait+0x4e/0x80 [ 92.407234] blkdev_issue_flush+0x31/0x50 [ 92.407526] ? punt_bios_to_rescuer+0x230/0x230 [ 92.407852] blkdev_fsync+0x1e/0x30 [ 92.408112] do_fsync+0x33/0x70 [ 92.408354] __x64_sys_fsync+0xb/0x10 [ 92.408625] do_syscall_64+0x43/0x90 [ 92.408895] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 92.409257] RIP: 0033:0x7f3cd76c6c44 > > > issued before the initialization of provider_data. Fixing this by > > initialize the provider_data through nd_region_desc to make sure the > > provider_data is ready after the pmem is created. > > > > Fixes 6e84200c0a29 ("virtio-pmem: Add virtio pmem driver") > > Signed-off-by: Jason Wang > > --- > > drivers/nvdimm/virtio_pmem.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > index 995b6cdc67ed..48f8327d0431 100644 > > --- a/drivers/nvdimm/virtio_pmem.c > > +++ b/drivers/nvdimm/virtio_pmem.c > > @@ -81,6 +81,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev) > > ndr_desc.res = &res; > > ndr_desc.numa_node = nid; > > ndr_desc.flush = async_pmem_flush; > > + ndr_desc.provider_data = vdev; > > For my untrained eye, why not > "dev_to_virtio(nd_region->dev.parent->parent)"? If that is indeed > equivalent "vdev" then you can do a follow-on cleanup patch to reduce > that syntax. Otherwise, if by chance they are not equivalent, then this > conversion is introducing a new problem. It is because nd_region hasn't been allocated at this time (which is allocated by nd_region_create() afterwards). Thanks > > Outside of that you can add: > > Reviewed-by: Dan Williams >