Re: [PATCH v2 2/3] fs: create helper file_user_path() for user displayed mapped file path

On Mon, Oct 9, 2023 at 10:00 AM Al Viro [off-list ref] wrote:

On Sat, Oct 07, 2023 at 11:44:32AM +0300, Amir Goldstein wrote:

quoted

@@ -93,7 +93,8 @@ static void show_faulting_vma(unsigned long address)
              char *nm = "?";

              if (vma->vm_file) {
-                     nm = file_path(vma->vm_file, buf, ARC_PATH_MAX-1);
+                     nm = d_path(file_user_path(vma->vm_file), buf,
+                                 ARC_PATH_MAX-1);
                      if (IS_ERR(nm))
                              nm = "?";

Umm...  At one point I considered this:
        if (vma->vm_file)
                pr_info("  @off 0x%lx in [%pD]  VMA: 0x%08lx to 0x%08lx\n",
                        vma->vm_start < TASK_UNMAPPED_BASE ?
                                address : address - vma->vm_start,
                        vma->vm_file, vma->vm_start, vma->vm_end);
        else
                pr_info("  @off 0x%lx in [anon]  VMA: 0x%08lx to 0x%08lx\n",
                        vma->vm_start < TASK_UNMAPPED_BASE ?
                                address : address - vma->vm_start,
                        vma->vm_start, vma->vm_end);
and to hell with that 'buf' thing...

It's fine by me.
That would be consistent with print_bad_pte().
I've never had to debug vma/pte faults, so I don't know
how much of the path is really valuable for debugging.

Thanks,
Amir.