Re: [PATCH] of/device: Really only set bus DMA mask when appropriate

["Richter, Robert" <Robert.Richter@cavium.com>]

On 06.11.18 11:54:15, Robin Murphy wrote:
> of_dma_configure() was *supposed* to be following the same logic as
> acpi_dma_configure() and only setting bus_dma_mask if some range was
> specified by the firmware. However, it seems that subtlety got lost in
> the process of fitting it into the differently-shaped control flow, and
> as a result the force_dma==true case ends up always setting the bus mask
> to the 32-bit default, which is not what anyone wants.
> 
> Make sure we only touch it if the DT actually said so.
> 
> Fixes: 6c2fb2ea7636 ("of/device: Set bus DMA mask as appropriate")
> Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
> Reported-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Tested-by: Robert Richter <robert.richter@cavium.com>

This patch makes the bad page state message on Cavium ThunderX below
disappear.

Note: The Fixes: tag suggests the issue was already in 4.19, but I
have seen it in 4.20-rc1 first and it was pulled into mainline with:

 cff229491af5 Merge tag 'dma-mapping-4.20' of git://git.infradead.org/users/hch/dma-mapping

-Robert


[   37.634555] BUG: Bad page state in process swapper/5  pfn:f3ebb
[   37.640483] page:ffff7e0003cfaec0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
[   37.648493] flags: 0xffff00000001000(reserved)
[   37.652942] raw: 0ffff00000001000 ffff7e0003cfaec8 ffff7e0003cfaec8 0000000000000000
[   37.660691] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[   37.668438] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
[   37.674880] bad because of flags: 0x1000(reserved)
[   37.679672] Modules linked in: ip6t_REJECT nf_reject_ipv6 xt_tcpudp ipt_REJECT nf_reject_ipv4 xt_conntrack ip6table_nat nf_nat_ipv6 ip6table_mangle iptable_nat nf_nat_ipv4 nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle ip6table_filter ip6_tables iptable_filter crct10dif_ce cavium_rng_vf rng_core ipmi_ssif thunderx_zip thunderx_edac ipmi_devintf cavium_rng ipmi_msghandler ip_tables x_tables xfs libcrc32c nicvf nicpf thunder_bgx thunder_xcv i2c_thunderx mdio_thunder mdio_cavium ipv6
[   37.723866] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.20.0-rc1-00012-gc106b1cbe843 #1
[   37.731874] Hardware name: Cavium ThunderX CRB/To be filled by O.E.M., BIOS 5.11 12/12/2012
[   37.740228] Call trace:
[   37.742677]  dump_backtrace+0x0/0x148
[   37.746334]  show_stack+0x14/0x1c
[   37.749643]  dump_stack+0x84/0xa8
[   37.752954]  bad_page+0xe4/0x144
[   37.756178]  free_pages_check_bad+0x7c/0x84
[   37.760355]  __free_pages_ok+0x22c/0x284
[   37.764272]  page_frag_free+0x64/0x68
[   37.767930]  skb_free_head+0x24/0x2c
[   37.771500]  skb_release_data+0x130/0x148
[   37.775504]  skb_release_all+0x24/0x30
[   37.779246]  kfree_skb+0x2c/0x54
[   37.782471]  ip_error+0x70/0x1d4
[   37.785693]  ip_rcv_finish+0x3c/0x50
[   37.789262]  ip_rcv+0xc0/0xd0
[   37.792225]  __netif_receive_skb_one_core+0x4c/0x70
[   37.797099]  __netif_receive_skb+0x2c/0x70
[   37.801190]  netif_receive_skb_internal+0x64/0x160
[   37.805976]  napi_gro_receive+0xa0/0xc4
[   37.809815]  nicvf_cq_intr_handler+0x930/0xc1c [nicvf]
[   37.814950]  nicvf_poll+0x30/0xb0 [nicvf]
[   37.818954]  net_rx_action+0x140/0x2f8
[   37.822697]  __do_softirq+0x11c/0x228
[   37.826354]  irq_exit+0xbc/0xd0
[   37.829491]  __handle_domain_irq+0x6c/0xb4
[   37.833581]  gic_handle_irq+0x8c/0x1a0
[   37.837324]  el1_irq+0xb0/0x128
[   37.840459]  arch_cpu_idle+0x10/0x18
[   37.844031]  default_idle_call+0x18/0x28
[   37.847948]  do_idle+0x194/0x258
[   37.851169]  cpu_startup_entry+0x20/0x24
[   37.855089]  secondary_start_kernel+0x144/0x168


> ---
> 
> Sorry about that... I guess I only have test setups that either have
> dma-ranges or where a 32-bit bus mask goes unnoticed :(
> 
> The Octeon and SMMU issues sound like they're purely down to this, and
> it's probably related to at least one of John's Hikey woes.
> 
> Robin.
> 
>  drivers/of/device.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 0f27fad9fe94..757ae867674f 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -149,7 +149,8 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
>  	 * set by the driver.
>  	 */
>  	mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
> -	dev->bus_dma_mask = mask;
> +	if (!ret)
> +		dev->bus_dma_mask = mask;
>  	dev->coherent_dma_mask &= mask;
>  	*dev->dma_mask &= mask;
>  
> -- 
> 2.19.1.dirty
> 
> 
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