On 07/20/2016 10:02 AM, Adrian Chadd wrote:
Hi,
The "right" way for the target CPU to interact with host CPU memory
(and vice versa, for mostly what it's worth) is to have the copy
engine copy (ie, "DMA") the pieces between them. This may be for
diagnostic purposes, but it's not supposed to be used like this for
doing wifi data exchange, right? :-P
Now, there /may/ be some alignment hilarity in various bits of code
and/or hardware. Eg, Merlin (AR9280) requires its descriptors to be
within a 4k block - the code to iterate through the descriptor
physical address space didn't do a "val = val + offset", it did
something in verilog like "val = (val & 0xffffc000) | (offset &
0x3fff)". This meant if you allocated a descriptor that started just
before the end of a 4k physmem aligned block, you'd end up with
exciting results. I don't know if there are any situations like this
in the ath10k hardware, but I'm sure there will be some gotchas
somewhere.
In any case, if ath10k is consuming too much bounce buffers, the calls
to allocate memory aren't working right and should be restricted to 32
bit addresses. Whether that's by using the DMA memory API (before it's
mapped) or passing in GFP_DMA32 is a fun debate.
(My test hardware arrived, so I'll test this all out today on
Peregrine-v2 and see if the driver works.)
I have been running this patch for a while:
ath10k: Use GPF_DMA32 for firmware swap memory.
This fixes OS crash when using QCA 9984 NIC on x86-64 system
without vt-d enabled.
Also tested on ea8500 with 9980, and x86-64 with 9980 and 9880.
All tests were with CT firmware.
Signed-off-by: Ben Greear <greearb@xxxxxxxxxxxxxxx>
-------------------- drivers/net/wireless/ath/ath10k/wmi.c --------------------
index e20aa39..727b3aa 100644
@@ -4491,7 +4491,7 @@ static int ath10k_wmi_alloc_chunk(struct ath10k *ar, u32 req_id,
if (!pool_size)
return -EINVAL;
- vaddr = kzalloc(pool_size, GFP_KERNEL | __GFP_NOWARN);
+ vaddr = kzalloc(pool_size, GFP_KERNEL | __GFP_NOWARN | GFP_DMA32);
if (!vaddr)
num_units /= 2;
}
It mostly seems to work, but then sometimes I get a splat like this below. It appears
it is invalid to actually do kzalloc with GFP_DMA32 (based on that BUG_ON that
hit in the new_slab method)??
Any idea for a more proper way to do this?
gfp: 4
------------[ cut here ]------------
kernel BUG at /home/greearb/git/linux-4.7.dev.y/mm/slub.c:1508!
invalid opcode: 0000 [#1] PREEMPT SMP
Modules linked in: coretemp hwmon ath9k intel_rapl ath10k_pci x86_pkg_temp_thermal ath9k_common ath10k_core intel_powerclamp ath9k_hw ath kvm iTCO_wdt mac80211
iTCO_vendor_support irqbypass snd_hda_codec_hdmi 6
CPU: 2 PID: 268 Comm: kworker/u8:5 Not tainted 4.7.2+ #16
Hardware name: To be filled by O.E.M. To be filled by O.E.M./ChiefRiver, BIOS 4.6.5 06/07/2013
Workqueue: ath10k_aux_wq ath10k_wmi_event_service_ready_work [ath10k_core]
task: ffff880036433a00 ti: ffff880036440000 task.ti: ffff880036440000
RIP: 0010:[<ffffffff8124592a>] [<ffffffff8124592a>] new_slab+0x39a/0x410
RSP: 0018:ffff880036443b58 EFLAGS: 00010092
RAX: 0000000000000006 RBX: 00000000024082c4 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffff88021e30dd08 RDI: ffff88021e30dd08
RBP: ffff880036443b90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000372 R12: ffff88021dc01200
R13: ffff88021dc00cc0 R14: ffff88021dc01200 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff88021e300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3e65c1c730 CR3: 0000000001e06000 CR4: 00000000001406e0
Stack:
ffffffff8127a4fc ffff0a01ffffff10 00000000024082c4 ffff88021dc01200
ffff88021dc00cc0 ffff88021dc01200 0000000000000001 ffff880036443c58
ffffffff81247ac6 ffff88021e31b360 ffff880036433a00 ffff880036433a00
Call Trace:
[<ffffffff8127a4fc>] ? __d_lookup+0x9c/0x160
[<ffffffff81247ac6>] ___slab_alloc+0x396/0x4a0
[<ffffffffa0f8e14d>] ? ath10k_wmi_event_service_ready_work+0x5ad/0x800 [ath10k_core]
[<ffffffff811f5279>] ? alloc_kmem_pages+0x9/0x10
[<ffffffff8120f203>] ? kmalloc_order+0x13/0x40
[<ffffffffa0f8e14d>] ? ath10k_wmi_event_service_ready_work+0x5ad/0x800 [ath10k_core]
[<ffffffff81247bf6>] __slab_alloc.isra.72+0x26/0x40
[<ffffffff81248767>] __kmalloc+0x147/0x1b0
[<ffffffffa0f8e14d>] ath10k_wmi_event_service_ready_work+0x5ad/0x800 [ath10k_core]
[<ffffffff811370a1>] ? dequeue_entity+0x261/0xac0
[<ffffffff8111c2d8>] process_one_work+0x148/0x420
[<ffffffff8111c929>] worker_thread+0x49/0x480
[<ffffffff8111c8e0>] ? rescuer_thread+0x330/0x330
[<ffffffff81121984>] kthread+0xc4/0xe0
[<ffffffff8184d75f>] ret_from_fork+0x1f/0x40
[<ffffffff811218c0>] ? kthread_create_on_node+0x170/0x170
Code: e9 65 fd ff ff 49 8b 57 20 48 8d 42 ff 83 e2 01 49 0f 44 c7 f0 80 08 40 e9 6f fd ff ff 89 c6 48 c7 c7 01 36 c7 81 e8 e8 40 fa ff <0f> 0b ba 00 10 00 00 be
5a 00 00 00 48 89 c7 48 d3 e2 e8 bf 18
RIP [<ffffffff8124592a>] new_slab+0x39a/0x410
RSP <ffff880036443b58>
---[ end trace ea3b0043b2911d93 ]---
static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
BUG();
}
return allocate_slab(s,
flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
}
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
