Re: [PATCH v2] scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR context

[Ziqi Chen]

On 6/18/2026 10:09 PM, Can Guo wrote:
> TX EQTR may run while devfreq gear scaling has quiesced the UFS tagset. In
> that context, functions ufshcd_tx_eqtr(), __ufshcd_tx_eqtr() and
> ufs_qcom_get_rx_fom() allocate memory with GFP_KERNEL. If direct reclaim
> is triggered, reclaim/writeback can depend on I/O to UFS device. Because
> the queue is quiesced, this can cause deadlock.
>
> Use memalloc_noio_save/restore() in ufshcd_tx_eqtr() to cover all
> allocations in the TX EQTR call tree, including:
> - params->eqtr_record in ufshcd_tx_eqtr()
> - eqtr_data in __ufshcd_tx_eqtr()
> - params in ufs_qcom_get_rx_fom()
>
> This is preferred over tagging individual call sites with GFP_NOIO, as it
> automatically covers any future allocations added anywhere in the call
> tree without requiring each caller to be aware of this constraint.
>
> Fixes: 03e5d38e2f98 ("scsi: ufs: core: Add support for TX Equalization")
> Closes: https://sashiko.dev/#/patchset/20260615132834.2985346-1-can.guo@xxxxxxxxxxxxxxxx?part=2
> Signed-off-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
Reviewed-by: Ziqi Chen <ziqi.chen@xxxxxxxxxxxxxxxx>