CVE-2022-50534 dm thin: Use last transaction's pmd->root when commit failed

In the Linux kernel, the following vulnerability has been resolved: dm thin: Use last transaction's pmd-root when commit failed Recently we found a softlock up problem in dm thin pool btree lookup code due to corrupted metadata: Kernel panic - not syncing: softlockup: hung tasks CPU: 7 PID: 26692...