On Thu, May 26, 2022 at 11:48:32AM +0300, Dan Carpenter wrote: > On Thu, May 26, 2022 at 02:16:34AM +0100, Matthew Wilcox wrote: > > Bizarre this started showing up now. The recent patch was: > > > > - info->alloced += compound_nr(page); > > - inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page); > > + info->alloced += folio_nr_pages(folio); > > + inode->i_blocks += BLOCKS_PER_PAGE << folio_order(folio); > > > > so it could tell that compound_order() was small, but folio_order() > > might be large? > > The old code also generates a warning on my test system. Smatch thinks > both compound_order() and folio_order() are 0-255. I guess because of > the "unsigned char compound_order;" in the struct page. It'd be nice if we could annotate that as "contains a value between 1 and BITS_PER_LONG - PAGE_SHIFT". Then be able to optionally enable a checker that ensures that's true on loads/stores. Maybe we need a language that isn't C :-P Ada can do this ... I don't think Rust can.
