On Mon, May 08, 2023 at 08:58:42PM GMT, Yan Zhao wrote: > In VFIO type1, vaddr_get_pfns() will try fault in MMIO PFNs after > pin_user_pages_remote() returns -EFAULT. > > follow_fault_pfn > fixup_user_fault > handle_mm_fault > handle_mm_fault > do_fault > do_shared_fault > do_fault > __do_fault > vfio_pci_mmap_fault > io_remap_pfn_range > remap_pfn_range > track_pfn_remap > vm_flags_set ==> mmap_assert_write_locked(vma->vm_mm) > remap_pfn_range_notrack > vm_flags_set ==> mmap_assert_write_locked(vma->vm_mm) > > As io_remap_pfn_range() will call vm_flags_set() to update vm_flags [1], > holding of mmap write lock is required. > So, update vfio_pci_mmap_fault() to drop mmap read lock and take mmap > write lock. > > [1] https://lkml.kernel.org/r/20230126193752.297968-3-surenb@xxxxxxxxxx > commit bc292ab00f6c ("mm: introduce vma->vm_flags wrapper functions") > commit 1c71222e5f23 > ("mm: replace vma->vm_flags direct modifications with modifier calls") > With linux-next I started noticing traces similar to the above without lockdep, since it has ba168b52bf8e ("mm: use rwsem assertion macros for mmap_lock"). Were there any follow ups to this? Sorry if my quick searching missed it. Thanks, drew
