On Fri, Mar 27, 2026 at 12:13:50PM -0700, Andrew Morton wrote:
> On Fri, 27 Mar 2026 20:03:05 +0800 Li Wang <[email protected]> wrote:
>
> > hugetlb_dio test uses sub-page offsets (pagesize / 2) to verify that
> > hugepages used as DIO user buffers are correctly unpinned at completion.
> >
> > However, on filesystems with a logical block size larger than half the
> > page size (e.g., 4K-sector block devices), these unaligned DIO writes
> > are rejected with -EINVAL, causing the test to fail unexpectedly.
> >
> > Add get_dio_alignment() to query the filesystem's required DIO alignment
> > via statx(STATX_DIOALIGN) and pass it to run_dio_using_hugetlb(). Skip
> > individual test cases whose write length is not a multiple of the
> > alignment, so that aligned cases are still tested.
> >
> > === Reproduce Steps ===
> >
> > # dd if=/dev/zero of=/tmp/test.img bs=1M count=512
> > # losetup --sector-size 4096 /dev/loop0 /tmp/test.img
> > # mkfs.xfs /dev/loop0
> > # mkdir -p /mnt/dio_test
> > # mount /dev/loop0 /mnt/dio_test
> >
> > // Modify test to open /mnt/dio_test and rebuild it:
> > - fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
> > + fd = open("/mnt/dio_test", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
> >
> > # getconf PAGESIZE
> > 4096
> >
> > # echo 100 >/proc/sys/vm/nr_hugepages
> >
> > # ./hugetlb_dio
> > TAP version 13
> > 1..4
> > # No. Free pages before allocation : 100
> > # No. Free pages after munmap : 100
> > ok 1 free huge pages from 0-12288
> > Bail out! Error writing to file
> > : Invalid argument (22)
> > # Planned tests != run tests (4 != 1)
> > # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> >
> > ...
> >
> > v2:
> > - Pass dio_align as a parameter to run_dio_using_hugetlb()
> > instead of generally page_size/2 alignment check.
> >
>
> Whee, AI review has decided that pre glibc-2.36 is a problem (last time
> it was pre-2.37).
Ok, will handle this build issue with old glibc.
> And it's forgotten the previous fs-doesnt-support-DIO issues. Did you
> alter that?
[Sorry, forgot to mention in change logs]
Yes, I added O_DIRECT flag back to the first open(). Then it'd skip into
a failure on filesystems that doesn't support O_DIRECT.
Also, statx on FS doesn't support DIO will set stx_dio_offset_align to 0,
which may led a division by zero issue, I added a zero check.
} else if ((stx.stx_mask & STATX_DIOALIGN) &&
stx.stx_dio_offset_align) {
> The get_dio_alignment-before-ksft_print_header thing seems legit.
+1
And, before sending v3, I would leave this patch for more days to
see if others comment.
--
Regards,
Li Wang
