Subject: Re: nvme crash - Re: linux-next: Tree for Aug 13

From: Christoph Hellwig <[email-masked]>
Date: Fri, 14 Aug 2020 13:08:24 +0100

On Fri, Aug 14, 2020 at 01:00:30PM +0100, John Garry wrote:
> 
> > > I have experienced this this crash below on linux-next for the last few days
> > > on my arm64 system. Linus' master branch today also has it.
> > Adding Robin and the iommu list as this seems to be in the dma-iommu
> > code.
> > 
> > > root@ubuntu:/home/john# insmod nvme.ko
> > > [148.254564] nvme 0000:81:00.0: Adding to iommu group 21
> > > [148.260973] nvme nvme0: pci function 0000:81:00.0
> > > root@ubuntu:/home/john# [148.272996] Unable to handle kernel NULL pointer
> > > dereference at virtual address 0000000000000010
> > > [148.281784] Mem abort info:
> > > [148.284584] ESR = 0x96000004
> > > [148.287641] EC = 0x25: DABT (current EL), IL = 32 bits
> > > [148.292950] SET = 0, FnV = 0
> > > [148.295998] EA = 0, S1PTW = 0
> > > [148.299126] Data abort info:
> > > [148.302003] ISV = 0, ISS = 0x00000004
> > > [148.305832] CM = 0, WnR = 0
> > > [148.308794] user pgtable: 4k pages, 48-bit VAs, pgdp=00000a27bf3c9000
> > > [148.315229] [0000000000000010] pgd=0000000000000000, p4d=0000000000000000
> > > [148.322016] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> > > [148.327577] Modules linked in: nvme nvme_core
> > > [148.331927] CPU: 56 PID: 256 Comm: kworker/u195:0 Not tainted
> > > 5.8.0-next-20200812 #27
> > > [148.339744] Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI RC0 -
> > > V1.16.01 03/15/2019
> > > [148.348260] Workqueue: nvme-reset-wq nvme_reset_work [nvme]
> > > [148.353822] pstate: 80c00009 (Nzcv daif +PAN +UAO BTYPE=--)
> > > [148.359390] pc : __sg_alloc_table_from_pages+0xec/0x238
> > > [148.364604] lr : __sg_alloc_table_from_pages+0xc8/0x238
> > > [148.369815] sp : ffff800013ccbad0
> > > [148.373116] x29: ffff800013ccbad0 x28: ffff0a27b3d380a8
> > > [148.378417] x27: 0000000000000000 x26: 0000000000002dc2
> > > [148.383718] x25: 0000000000000dc0 x24: 0000000000000000
> > > [148.389019] x23: 0000000000000000 x22: ffff800013ccbbe8
> > > [148.394320] x21: 0000000000000010 x20: 0000000000000000
> > > [148.399621] x19: 00000000fffff000 x18: ffffffffffffffff
> > > [148.404922] x17: 00000000000000c0 x16: fffffe289eaf6380
> > > [148.410223] x15: ffff800011b59948 x14: ffff002bc8fe98f8
> > > [148.415523] x13: ff00000000000000 x12: ffff8000114ca000
> > > [148.420824] x11: 0000000000000000 x10: ffffffffffffffff
> > > [148.426124] x9 : ffffffffffffffc0 x8 : ffff0a27b5f9b6a0
> > > [148.431425] x7 : 0000000000000000 x6 : 0000000000000001
> > > [148.436726] x5 : ffff0a27b5f9b680 x4 : 0000000000000000
> > > [148.442027] x3 : ffff0a27b5f9b680 x2 : 0000000000000000
> > > [148.447328] x1 : 0000000000000001 x0 : 0000000000000000
> > > [148.452629] Call trace:
> > > [148.455065]__sg_alloc_table_from_pages+0xec/0x238
> > > [148.459931]sg_alloc_table_from_pages+0x18/0x28
> > > [148.464541]iommu_dma_alloc+0x474/0x678
> > > [148.468455]dma_alloc_attrs+0xd8/0xf0
> > > [148.472193]nvme_alloc_queue+0x114/0x160 [nvme]
> > > [148.476798]nvme_reset_work+0xb34/0x14b4 [nvme]
> > > [148.481407]process_one_work+0x1e8/0x360
> > > [148.485405]worker_thread+0x44/0x478
> > > [148.489055]kthread+0x150/0x158
> > > [148.492273]ret_from_fork+0x10/0x34
> > > [148.495838] Code: f94002c3 6b01017f 540007c2 11000486 (f8645aa5)
> > > [148.501921] ---[ end trace 89bb2b72d59bf925 ]---
> > > 
> > > Anything to worry about? I guess not since we're in the merge window, but
> > > mentioning just in case ...
> 
> I bisected, and this patch looks to fix it (note the comments below the
> '---'):
> 
> From 263891a760edc24b901085bf6e5fe2480808f86d Mon Sep 17 00:00:00 2001
> From: John Garry <[email-masked]>
> Date: Fri, 14 Aug 2020 12:45:18 +0100
> Subject: [PATCH] nvme-pci: Use u32 for nvme_dev.q_depth
> 
> Recently nvme_dev.q_depth was changed from int to u16 type.
> 
> This falls over for the queue depth calculation in nvme_pci_enable(),
> where NVME_CAP_MQES(dev->ctrl.cap) + 1 may overflow, as NVME_CAP_MQES()
> gives a 16b number also. That happens for me, and this is the result:

Oh, interesting.  Please also switch the module option parsing to
use kstrtou32 and param_set_uint and send this as a formal patch.

Thanks!