On 2/8/21 2:52 PM, Song Liu wrote:
Introduce task_vma bpf_iter to print memory information of a process. It can be used to print customized information similar to /proc/<pid>/maps. Current /proc/<pid>/maps and /proc/<pid>/smaps provide information of vma's of a process. However, these information are not flexible enough to cover all use cases. For example, if a vma cover mixed 2MB pages and 4kB pages (x86_64), there is no easy way to tell which address ranges are backed by 2MB pages. task_vma solves the problem by enabling the user to generate customize information based on the vma (and vma->vm_mm, vma->vm_file, etc.). To access the vma safely in the BPF program, task_vma iterator holds target mmap_lock while calling the BPF program. If the mmap_lock is contended, task_vma unlocks mmap_lock between iterations to unblock the writer(s). This lock contention avoidance mechanism is similar to the one used in show_smaps_rollup(). Signed-off-by: Song Liu <songliubraving@xxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
