Linux kernel version 4.19.7 is released and does not solve the data corruption error

After the Linux kernel 4.19 release, for several weeks Complaints about destroyed file systems on multiple users became more frequent, so the developers initially did not take this into account.

Seeing that these complaints were on the rise, the concern arose and the Linux kernel developers have now found and fixed the corresponding bug.

At first the developers had assumed it was a problem with the Ext4 file systems.

So they hadn't paid attention to it, but when the developers decided to tackle the problem They discovered that the cause is in the framework called Multi-queue Block I / O Queuing Mechanism ("Blk-mq" for short) and thus other file systems are affected.

Fortunately, the error only occurs under certain circumstances, but it can be reproduced.

BLK-MQ allows you to handle multiple queues spread over CPU threads that can then be mapped to the number of hardware queues available to a storage device.

Over time, more drivers have been supported by BLK-MQ, while key drivers like NVMe have supported it for quite some time.

Also other file systems were affected (albeit to a lesser extent), only that EXT4 is the most common filesystem and therefore most of the reports made were from this.

Several users, including upstream Linux kernel developers, have found that their data stability is improved by disabling MQ code.

The developers fixed the bug so data loss with the next kernel version should be a thing of the past.

Linux kernel version 4.19.7 is released

Also recently the new update of the Linux kernel branch 4.19.x was released, reaching its version 4.19.7.

The announcement was made by developer Greg Kroah-Hartman. In this new release of Linux Kernel 4.19.7 fixes are released for better performance of PCI Express.

Also update older branches of LTS, the Linux kernel 4.19.7 is notable for having returned the new STIBP code to provide better behavior around the Cross-HT Specter V2 mitigation.

Since it only applies to opt-in processes through prctl and Seccomp by default, instead of all processes.

System performance is not affected, so the resulting code was from the merge of last week's jobs for Kernel 4.20.

Other modifications

The other notable change in Linux 4.19.7 is a PCI Express code fix that was causing problems for those using PCI Express 3.0 graphics cards on older motherboards that support PCIe 1.0 and 2.0.

This problem was causing problems in particular for Radeon GPU cards.

Besides the Linux kernel 4.19.7, updates for versions 4.14.86 and 4.9.143 were also released to complete the list of stable versions.

Goodbye to MPX in the Linux kernel

Another novelty in relation to the kernel is that the Memory Protection Extensions support which will be removed from the Linux 4.21 Kernel.

Dave Hansen issued a pull request to remove Intel MPX support in the Linux kernel.

MPX support was introduced with Skylake processors and designed to provide greater security.

Therefore, provide pointer reference controls at run time to avoid potential buffer overflows.

But its adoption did not take off much. Since then, software-based solutions have become more powerful and with the AddressSanitizer project type.

Finally, the bug fix with the EXT4 corruption issue generated by BLK-MQ that was reported after the Linux kernel 4.19 release, was not included in this Linux kernel 4.19.7 release so we hope that in a few days the Linux kernel 4.19.8 will be protected against this data corruption problem.