On Tue, Aug 04, 2015 at 03:58:00PM -0400, Matthew Wilcox wrote: > diff --git a/mm/memory.c b/mm/memory.c > index b94b587..5f46350 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2426,11 +2426,16 @@ void unmap_mapping_range(struct address_space *mapping, > details.last_index = ULONG_MAX; > > > - /* DAX uses i_mmap_lock to serialise file truncate vs page fault */ > - i_mmap_lock_write(mapping); > + /* > + * DAX already holds i_mmap_lock to serialise file truncate vs > + * page fault and page fault vs page fault. > + */ > + if (!IS_DAX(mapping->host)) > + i_mmap_lock_write(mapping); > if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) > unmap_mapping_range_tree(&mapping->i_mmap, &details); > - i_mmap_unlock_write(mapping); > + if (!IS_DAX(mapping->host)) > + i_mmap_unlock_write(mapping); > } > EXPORT_SYMBOL(unmap_mapping_range); Huh? What protects mapping->i_mmap here? I don't see anything up by stack taking the lock. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>