On 2/5/25 09:47, Alistair Popple wrote: > dax_layout_busy_page_range() is used by file systems to scan the DAX > page-cache to unmap mapping pages from user-space and to determine if > any pages in the given range are busy, either due to ongoing DMA or > other get_user_pages() usage. > > Currently it checks to see the file mapping is mapped into user-space > with mapping_mapped() and returns early if not, skipping the check for > DMA busy pages. This is wrong as pages may still be undergoing DMA > access even if they have subsequently been unmapped from > user-space. Fix this by dropping the check for mapping_mapped(). > > Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx> > Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx> > Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > fs/dax.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 21b4740..5133568 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -690,7 +690,7 @@ struct page *dax_layout_busy_page_range(struct address_space *mapping, > if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) > return NULL; > > - if (!dax_mapping(mapping) || !mapping_mapped(mapping)) > + if (!dax_mapping(mapping)) > return NULL; > > /* If end == LLONG_MAX, all pages from start to till end of file */ I think the patch should probably also add if (mapping_mapped(mapping)) unmap_mapping_pages(mapping, start_idx, end_idx - start_idx + 1, 0); But I don't think it's a blocker unmap_mapping_pages() should do the right thing internally Acked-by: Balbir Singh <balbirs@xxxxxxxxxx>
