Linus Torvalds warned users about the discovery of a critical issue in the experimental release of the 5.12-rc1 kernel, advised against installing this version for testing, and renamed the "v5.12-rc1" Git tag to "v5.12-rc1-dontuse". The problem manifests itself when using the paging file and can lead to data corruption in the file system in which this file is located.
In particular, the changes proposed in 5.12-rc1 disrupted the normal work with the swap file and led to the loss of the start offset of the swap data in the FS, which led to disastrous results - the contents of the FS were overwritten with random swap data. The problem only affects systems with a swapfile (swapfile) and does not appear when using a separate disk partition for swap.
Source: opennet.ru