GDB uses /proc/PID/mem to access memory of the target process. GDB doesn't untag addresses manually, but relies on kernel to do the right thing.
mem_rw() of procfs uses access_remote_vm() to get data from the target process. It worked fine until recent changes in __access_remote_vm() that now checks if there's VMA at target address using raw address.
Untag the address before looking up the VMA.
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reported-by: Christina Schimpe christina.schimpe@intel.com Fixes: eee9c708cc89 ("gup: avoid stack expansion warning for known-good case") Cc: stable@vger.kernel.org --- mm/memory.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c index 01f39e8144ef..3be9db30db32 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5701,6 +5701,9 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, if (mmap_read_lock_killable(mm)) return 0;
+ /* Untag the address before looking up the VMA */ + addr = untagged_addr_remote(mm, addr); + /* Avoid triggering the temporary warning in __get_user_pages */ if (!vma_lookup(mm, addr) && !expand_stack(mm, addr)) return 0;