Re: [linux-next:master] BUILD REGRESSION 8cb8311e95e3bb58bd84d6350365f14a718faa6d
Matthew Wilcox <[email protected]>
| Newsgroups | gmane.comp.emulators.kvm.devel,gmane.linux.kernel.virtualization,gmane.linux.network,gmane.linux.ports.riscv,gmane.linux.drivers.rdma,gmane.linux.kernel.pci,gmane.linux.parport,gmane.linux.ports.arm.omap,gmane.linux.kernel.mm,gmane.linux.ports.arm.kernel,gmane.comp.video.dri.devel,gmane.linux.kernel.bpf,gmane.comp.freedesktop.amd-gfx,gmane.linux.alsa.devel |
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| Message-ID | <[email protected]> |
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.