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 1715A23B5 for ; Fri, 24 Jun 2022 06:46:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1656053189; 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=FURCV1ZKg+XFtI0cdvnarruVZ9TexRazF46sbHFqTGM=; b=cHeCU8wz5dHN9RF4UO3Qeb5FUC3+JzcVIaDN/xIg9Bq9BBV/ndSTwNTo9HRmVp2KS3urpY NOB8uEqkmP9DoOaPHmOtGaZYvSiHuKe9L8hrUY5pbOE+O/Ow21WK5+rp1COebL71WxQvhu hy2vjt2KMjkQSRPKo+gLguG0EnMenFM= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-349-pQP8FAl4M7-YjvRzaWeVVA-1; Fri, 24 Jun 2022 02:46:28 -0400 X-MC-Unique: pQP8FAl4M7-YjvRzaWeVVA-1 Received: by mail-wm1-f72.google.com with SMTP id n35-20020a05600c3ba300b003a02d7bd5caso1026420wms.2 for ; Thu, 23 Jun 2022 23:46:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=FURCV1ZKg+XFtI0cdvnarruVZ9TexRazF46sbHFqTGM=; b=g2QTr3+jTtEhKu/X5IZGj/4TYg3XNLjRnReuVCPVtLyQCtQnxSmuiKs6HX7W8VFdDW wbubpd5gdsdqqVbqhDsJVUV+nGSUNlr07lw1u5pko6fsuTL658owhGzjEAMK5gka49J9 8dIHau2cIFYlLPEV/DtoVUAo9lzxOUR0cYmKYba6RixrWtqs8fLMWrayDuLAd/Bp6Exg v8M/PORA2sW+rUBtOHmOFY5Am+HhqyGQyWrMbeIKZqc8W6qJmYa+sKJ95jdI6sHmp7sb bJYfZYFX8jikAqpL9NeFRFlC/MCGCPlqYJ+ol50G3lSVmHgr27Jru1fwyNT27/UMB9K4 7efQ== X-Gm-Message-State: AJIora9nOpdzJ/GORrfrqRXFsXJNdqOKLRWCPSlziDU4q8KiAku1uUVG 4acLyI796ts3pwntVcnmLf/m4trxmsMtG2NceMyZlks0QCj75VYyDK168v4FVd3qQaVZwM9xLv2 rGVpDiY/oG/VtsNGi X-Received: by 2002:a05:600c:4ed4:b0:39a:de6b:40e4 with SMTP id g20-20020a05600c4ed400b0039ade6b40e4mr1881904wmq.100.1656053186571; Thu, 23 Jun 2022 23:46:26 -0700 (PDT) X-Google-Smtp-Source: AGRyM1u/Hv+6FJ1QbBhEAWMrVConW5H7jcntbki8PEWp5pvDMroVKuXsy+/Uo976Ie6lWEnUKPVkBw== X-Received: by 2002:a05:600c:4ed4:b0:39a:de6b:40e4 with SMTP id g20-20020a05600c4ed400b0039ade6b40e4mr1881880wmq.100.1656053186285; Thu, 23 Jun 2022 23:46:26 -0700 (PDT) Received: from redhat.com ([2.55.188.216]) by smtp.gmail.com with ESMTPSA id u15-20020a5d434f000000b0021b970a68f9sm1417883wrr.26.2022.06.23.23.46.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jun 2022 23:46:25 -0700 (PDT) Date: Fri, 24 Jun 2022 02:46:22 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Dan Williams , vishal.l.verma@intel.com, "Jiang, Dave" , ira.weiny@intel.com, nvdimm@lists.linux.dev Subject: Re: [PATCH 1/2] virtio_pmem: initialize provider_data through nd_region_desc Message-ID: <20220624024548-mutt-send-email-mst@kernel.org> References: <20220620081519.1494-1-jasowang@redhat.com> <62b2476ca8c21_892072947a@dwillia2-xfh.notmuch> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Jun 22, 2022 at 11:22:00AM +0800, Jason Wang wrote: > 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 Jason pls repost everything with this info included, and maybe really do make the patch minimal as Dan suggested. > > > > > 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 > >