Linux Kernel in_atomic() Handling Vulnerability in Secure Storage Access

A vulnerability exists in the Linux kernel's handling of user space accesses to non-exported pages in atomic context. This issue can lead to improper resolution of page faults, causing sleeping functions to be called from an invalid context. The vulnerability has been observed in kernel version 6.16.0-20250531.rc0.git0.69b3a602feac.63.fc42.s390x, with debug options enabled, allowing call traces to be generated that detail the erroneous context handling. The issue arises because the mmap_lock cannot be taken while in atomic context, necessitating a process context access to properly resolve the page fault.

Impact

Exploitation of this vulnerability disrupts the normal handling of page faults in atomic context, potentially leading to incorrect process behavior or system instability.