mm/damon/sysfs: catch commit test ctx alloc failure

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: catch commit test ctx alloc failure Patch series "mm/damon/sysfs: fix commit test damon_ctx [de]allocation". DAMON sysfs interface dynamically allocates and uses a damon_ctx object for testing if given inputs for online DAMON parameters update is valid. The object is being used without an allocation failure check, and leaked when the test succeeds. Fix the two bugs. This patch (of 2): The damon_ctx for testing online DAMON parameters commit inputs is used without its allocation failure check. This could result in an invalid memory access. Fix it by directly returning an error when the allocation failed.