Messages in this thread | | | From | "Fabio M. De Francesco" <> | Subject | Re: [RFC PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE | Date | Mon, 25 Apr 2022 03:47:38 +0200 |
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On domenica 24 aprile 2022 12:48:06 CEST Fabio M. De Francesco wrote: > Call VM_BUG_ON() if offset + len > PAGE_SIZE. > > This is an RFC patch because I'm not sure if we actually need to BUG_ON(),
Actually I considered VM_BUG_ON() for consistency with the other functions in highmem.h
What about VM_WARN_ON_ONCE() here and also in memset_page?
Thanks,
Fabio
> so I'd like to know what Maintainers and other developers think about this > proposal. > > Please note that memset_page() uses VM_BUG_ON() to prevent the same issue. > > Furthermore, I also cannot understand why memset_page() does not call > flush_dcache_page() after memset() but I suppose that the different > implementations of these two functions should be addressed in another RFC. > > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> > --- > include/linux/highmem.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index c3d562b5f0c1..bdb16d5f8148 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -349,6 +349,8 @@ static inline void memcpy_to_page(struct page *page, size_t offset, > static inline void memzero_page(struct page *page, size_t offset, size_t len) > { > char *addr = kmap_local_page(page); > + > + VM_BUG_ON(offset + len > PAGE_SIZE); > memset(addr + offset, 0, len); > flush_dcache_page(page); > kunmap_local(addr); > -- > 2.34.1 > >
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