In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR cont

In the Linux kernel, the following vulnerability has been resolved:

scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR context

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.

[mkp: fix label as suggested by Bart]