[PATCH] Linux: Fix tst-copy_file_range-large test on recent kernels [BZ #33498]

[H.J. Lu]

On Mon, Oct 27, 2025 at 7:21 AM Collin Funk <collin.funk1@gmail.com> wrote:
>
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>
> > It failed now with 32-bit build under 6.17.4 kernel:
> >
> > FAIL: misc/tst-copy_file_range-large
> > original exit status 1
> > ../sysdeps/unix/sysv/linux/tst-copy_file_range-large.c:179: numeric
> > comparison failure
> >    left: 2147479552 (0x7ffff000); from: copied
> >   right: 4294963200 (0xfffff000); from: UINT_MAX & ~(getpagesize () - 1)
>
> I think I see the issue. On 32-bit platforms ssize_t is a signed 32-bit
> integer. Therefore I would expect it to pass with the following patch:
>
>     $ git diff master
>     diff --git a/sysdeps/unix/sysv/linux/tst-copy_file_range-large.c b/sysdeps/unix/sysv/linux/tst-copy_file_range-large.c
>     index 9eafb8c425..184877b91c 100644
>     --- a/sysdeps/unix/sysv/linux/tst-copy_file_range-large.c
>     +++ b/sysdeps/unix/sysv/linux/tst-copy_file_range-large.c
>     @@ -176,7 +176,7 @@ test_size (struct support_fuse *f, off64_t size)
>           <https://github.com/torvalds/linux/commit/1e08938c3694f707bb165535df352ac97a8c75c9>.
>        */
>        if (copied != size)
>     -    TEST_COMPARE (copied, UINT_MAX & ~(getpagesize () - 1));
>     +    TEST_COMPARE (copied, (SSIZE_MAX & ~(getpagesize () - 1)));
>
>        xclose (dest_fd);
>        xclose (source_fd);
>
> But that return value seems incorrect, since (UINT_MAX & PAGE_MASK)
> bytes should be copied, per the fix [1]. I would have to set up a 32-bit
> VM to double check. But I have a feeling we will need another Linux bug

I saw this when building and running i686 glibc on Linux/x86-64 configured with

$ BUILD_CC="gcc" TEST_CC="gcc -m32 -m32" TEST_CXX="g++ -m32 -m32"
CC="gcc -m32" CXX="g++ -m32" CFLAGS="-O2 -g -march=i686"
/export/gnu/import/git/sources/glibc/configure --prefix=/usr
--without-selinux --target=i686-linux --build=i686-linux
--host=i686-linux --enable-hardcoded-path-in-tests
--enable-large-benchtests --enable-stack-protector=all
--with-timeoutfactor=3

> report.
>
> Collin
>
> [1] https://github.com/torvalds/linux/commit/1e08938c3694f707bb165535df352ac97a8c75c9



-- 
H.J.