On 11/4/21 2:31 PM, Song Liu wrote:
In some profiler use cases, it is necessary to map an address to the backing file, e.g., a shared library. bpf_find_vma helper provides a flexible way to achieve this. bpf_find_vma maps an address of a task to the vma (vm_area_struct) for this address, and feed the vma to an callback BPF function. The callback function is necessary here, as we need to ensure mmap_sem is unlocked. It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem safely when irqs are disable, we use the same mechanism as stackmap with build_id. Specifically, when irqs are disabled, the unlocked is postponed in an irq_work. Refactor stackmap.c so that the irq_work is shared among bpf_find_vma and stackmap helpers. Reported-by: kernel test robot <lkp@xxxxxxxxx>
You don't need the above "Reported-by".
Signed-off-by: Song Liu <songliubraving@xxxxxx>
LGTM. Acked-by: Yonghong Song <yhs@xxxxxx>
