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Message-ID: <cda4c968-29b0-4e64-9d20-bb2f0e6cd32d@quicinc.com>
Date: Fri, 23 Feb 2024 17:24:24 -0800
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Subject: Re: [PATCH] wifi: ath11k: decrease MHI channel buffer length to 8KB
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To: Baochen Qiang <quic_bqiang@quicinc.com>, <ath11k@lists.infradead.org>
CC: <linux-wireless@vger.kernel.org>
References: <20240223053111.29170-1-quic_bqiang@quicinc.com>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <20240223053111.29170-1-quic_bqiang@quicinc.com>
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On 2/22/2024 9:31 PM, Baochen Qiang wrote:
> Currently buf_len field of ath11k_mhi_config_qca6390 is assigned
> with 0, making MHI use a default size, 64KB, to allocate channel
> buffers. This is likely to fail in some scenarios where system
> memory is highly fragmented and memory compaction or reclaim is
> not allowed.
> 
> There is a fail report which is caused by it:
> kworker/u32:45: page allocation failure: order:4, mode:0x40c00(GFP_NOIO|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0
> CPU: 0 PID: 19318 Comm: kworker/u32:45 Not tainted 6.8.0-rc3-1.gae4495f-default #1 openSUSE Tumbleweed (unreleased) 493b6d5b382c603654d7a81fc3c144d59a1dfceb
> Workqueue: events_unbound async_run_entry_fn
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x47/0x60
>  warn_alloc+0x13a/0x1b0
>  ? srso_alias_return_thunk+0x5/0xfbef5
>  ? __alloc_pages_direct_compact+0xab/0x210
>  __alloc_pages_slowpath.constprop.0+0xd3e/0xda0
>  __alloc_pages+0x32d/0x350
>  ? mhi_prepare_channel+0x127/0x2d0 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  __kmalloc_large_node+0x72/0x110
>  __kmalloc+0x37c/0x480
>  ? mhi_map_single_no_bb+0x77/0xf0 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  ? mhi_prepare_channel+0x127/0x2d0 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  mhi_prepare_channel+0x127/0x2d0 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  __mhi_prepare_for_transfer+0x44/0x80 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  ? __pfx_____mhi_prepare_for_transfer+0x10/0x10 [mhi 40df44e07c05479f7a6e7b90fba9f0e0031a7814]
>  device_for_each_child+0x5c/0xa0
>  ? __pfx_pci_pm_resume+0x10/0x10
>  ath11k_core_resume+0x65/0x100 [ath11k a5094e22d7223135c40d93c8f5321cf09fd85e4e]
>  ? srso_alias_return_thunk+0x5/0xfbef5
>  ath11k_pci_pm_resume+0x32/0x60 [ath11k_pci 830b7bfc3ea80ebef32e563cafe2cb55e9cc73ec]
>  ? srso_alias_return_thunk+0x5/0xfbef5
>  dpm_run_callback+0x8c/0x1e0
>  device_resume+0x104/0x340
>  ? __pfx_dpm_watchdog_handler+0x10/0x10
>  async_resume+0x1d/0x30
>  async_run_entry_fn+0x32/0x120
>  process_one_work+0x168/0x330
>  worker_thread+0x2f5/0x410
>  ? __pfx_worker_thread+0x10/0x10
>  kthread+0xe8/0x120
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork+0x34/0x50
>  ? __pfx_kthread+0x10/0x10
>  ret_from_fork_asm+0x1b/0x30
>  </TASK>
> 
> Actually those buffers are used only by QMI target -> host communication.
> And for WCN6855 and QCA6390, the largest packet size for that is less
> than 6KB. So change buf_len field to 8KB, which results in order 1
> allocation if page size is 4KB. In this way, we can at least save some
> memory, and as well as decrease the possibility of allocation failure
> in those scenarios.
> 
> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
> 
> Reported-by: Vlastimil Babka <vbabka@suse.cz>
> Closes: https://lore.kernel.org/ath11k/96481a45-3547-4d23-ad34-3a8f1d90c1cd@suse.cz/
> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>