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

[Can Guo <can.guo@oss.qualcomm.com>]

On 6/16/2026 9:31 PM, Bart Van Assche wrote:
> On 6/16/26 2:06 AM, Can Guo wrote:
>> diff --git a/drivers/ufs/core/ufs-txeq.c b/drivers/ufs/core/ufs-txeq.c
>> index 4b264adfdf49..3a2fb5329d27 100644
>> --- a/drivers/ufs/core/ufs-txeq.c
>> +++ b/drivers/ufs/core/ufs-txeq.c
>> @@ -1059,7 +1059,7 @@ static int __ufshcd_tx_eqtr(struct ufs_hba *hba,
>>                   struct ufs_pa_layer_attr *pwr_mode)
>>   {
>>       struct ufshcd_tx_eqtr_data *eqtr_data  __free(kfree) =
>> -        kzalloc(sizeof(*eqtr_data), GFP_KERNEL);
>> +        kzalloc(sizeof(*eqtr_data), GFP_NOIO);
>>       struct tx_eqtr_iter h_iter = {};
>>       struct tx_eqtr_iter d_iter = {};
>>       u32 gear = pwr_mode->gear_tx;
>> @@ -1217,7 +1217,7 @@ static int ufshcd_tx_eqtr(struct ufs_hba *hba,
>>       if (!params->eqtr_record) {
>>           params->eqtr_record = devm_kzalloc(hba->dev,
>>                              sizeof(*params->eqtr_record),
>> -                           GFP_KERNEL);
>> +                           GFP_NOIO);
>>           if (!params->eqtr_record)
>>               return -ENOMEM;
>>       }
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index c084ccc72523..e7f104987c6a 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -2760,7 +2760,7 @@ static int ufs_qcom_get_rx_fom(struct ufs_hba 
>> *hba,
>>                      struct tx_eqtr_iter *d_iter)
>>   {
>>       struct ufshcd_tx_eq_params *params __free(kfree) =
>> -        kzalloc(sizeof(*params), GFP_KERNEL);
>> +        kzalloc(sizeof(*params), GFP_NOIO);
>>       struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>>       struct ufs_pa_layer_attr old_pwr_info;
>>       u32 fom[PA_MAXDATALANES] = { 0 };
>
> Modifying individual memory allocation calls is error prone. The next
> person who modifies this code may not be aware of this conversation and
> might reintroduce a GFP_KERNEL allocation in the TX equalization code.
>
> Please use memalloc_noio_save() and memalloc_noio_restore() instead of
> changing GFP_KERNEL into GFP_NOIO. Additionally, please add a comment
> above the memalloc_noio_save() call that explains why it is necessary.
> See also https://docs.kernel.org/core-api/gfp_mask-from-fs-io.html.
Thanks for the suggestion, using use memalloc_noio_save() and
memalloc_noio_restore() is indeed a better solution.

Best Regards,
Can Guo.
>
> Thanks,
>
> Bart.