[BUG] mm: truncate: a possible sleep-in-atomic-context bug in truncate_exceptional_pvec_entries()

[Jia-Ju Bai]

The kernel may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] schedule
fs/dax.c, 259: schedule in get_unlocked_mapping_entry
fs/dax.c, 450: get_unlocked_mapping_entry in __dax_invalidate_mapping_entry
fs/dax.c, 471: __dax_invalidate_mapping_entry in dax_delete_mapping_entry
mm/truncate.c, 97: dax_delete_mapping_entry in 
truncate_exceptional_pvec_entries
mm/truncate.c, 82: spin_lock_irq in truncate_exceptional_pvec_entries

I do not find a good way to fix, so I only report.
This is found by my static analysis tool (DSAC).


Thanks,
Jia-Ju Bai