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b=hybSj+etFTy1+LIAuCzZvsp25MVzR795OuJzHMQNu4IsJoubutQLiPHYFfZ9ujqrd Sd5018EiDDavI+or7SivXwvU8YK/rtLpP4P3z9Wo9YndtRGYXNDOoZvGpjl6dLayWO YRydMIXlNCoObElT4BCKBzKqZ9aJNRArGPHM0I1RgOHIBdOS8TPOedcza/zLxWlGH+ Kmx1S88nn8skMIdod6KI+DyLkVUx1kGMxDiodVzCWrJYQSYSXGota10fVu2e5XF1nq wrff+Ia1MSPj6p64ZoGJei2r5hHJ7phQt0cGqYmz46c1XVk5pMFalfIs3WpCYFK64E VMIdD8U94skfQ== Message-ID: Date: Mon, 30 Mar 2026 08:02:01 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] selftests/mm: skip hugetlb_dio tests when DIO alignment is incompatible To: Li Wang , akpm@linux-foundation.org, rppt@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Cc: aubaker@redhat.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20260330053915.75442-1-liwang@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 75C174000C X-Stat-Signature: xjc4ubxya136f3mkd77f5umma3io3n44 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774850527-755767 X-HE-Meta: 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 4kGTEusd gV/Mm8KgK/I45dVrDF3h4cF7NLjYN4I+8jDfV82WqkECrZ7fqah6GO6afjpSlJzIlXvRUZT9ucqhWoea9vUCcMwg+hey1qXBHwIHKgwdL/dINhYy2Z0IWduKxk2QMj6MMLmHMIb9ge6PYEdoYfXnXe3lXzB1VX2YvMXz9pqVf8ORft2QwUAEyr7+B4CcvjxdsbDB+0ielx+jyklPgHCRhNlJWr8ZXKUtVU0NDabTZ7UISicFWyp18HpZNQc5X8RwpJr+tzsP4ENkNY8vHjge8qgE9GZXS7nc6sNgyUHSciAJSEk8PcSYrr/5a/dHKF2GrKhpBkxqgHkpYzL8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/30/26 07:39, Li Wang 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 writesize/buf-offset 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 > > Signed-off-by: Li Wang > --- > > Notes: > v3: > - Adopt statx raw syscall to build on older glibc. > - add buf offset alignment check as well > v2: > - Pass dio_align as a parameter to run_dio_using_hugetlb() > instead of generally page_size/2 alignment check. > - Add O_DIRECT flag back to the first open(). > - Add stx_dio_offset_align zero check. > > tools/testing/selftests/mm/hugetlb_dio.c | 62 +++++++++++++++++------- > 1 file changed, 45 insertions(+), 17 deletions(-) > > diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c > index 9ac62eb4c97d..b125092fc6c1 100644 > --- a/tools/testing/selftests/mm/hugetlb_dio.c > +++ b/tools/testing/selftests/mm/hugetlb_dio.c > @@ -17,10 +17,41 @@ > #include > #include > #include > +#include > #include "vm_util.h" > #include "kselftest.h" > > -void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) > +#define HP_DIO_TMPDIR "/tmp" > + > +#ifndef STATX_DIOALIGN > +#define STATX_DIOALIGN 0x00002000U > +#endif > + > +unsigned int get_dio_alignment(void) > +{ > + int fd, ret; > + struct statx stx; > + unsigned int dio_align = 1; > + > + fd = open(HP_DIO_TMPDIR, O_TMPFILE | O_RDWR | O_DIRECT, 0664); > + if (fd < 0) > + ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno)); > + > + ret = syscall(__NR_statx, fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &stx); > + if (ret < 0) { > + ksft_perror("statx() failed"); > + } else if ((stx.stx_mask & STATX_DIOALIGN) && > + stx.stx_dio_offset_align) { > + dio_align = stx.stx_dio_offset_align; > + } > + > + close(fd); > + > + return dio_align; > +} > + > +void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off, > + unsigned int dio_align) > { > int fd; > char *buffer = NULL; > @@ -33,6 +64,12 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) > const int mmap_prot = PROT_READ | PROT_WRITE; > > writesize = end_off - start_off; > + if (start_off % dio_align != 0 || writesize % dio_align != 0) { > + ksft_test_result_skip("DIO alignment (%u) incompatible with " > + "buf offset %u and writesize %zu\n", > + dio_align, start_off, writesize); > + return; > + } > > /* Get the default huge page size */ > h_pagesize = default_huge_page_size(); > @@ -40,7 +77,7 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) > ksft_exit_fail_msg("Unable to determine huge page size\n"); > > /* Open the file to DIO */ This comment is misleading as we are not opening "the" file, but we create a new one. See below, maybe we should clean that up. > - fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664); > + fd = open(HP_DIO_TMPDIR, O_TMPFILE | O_RDWR | O_DIRECT, 0664); > if (fd < 0) > ksft_exit_fail_perror("Error opening file\n"); > > @@ -89,37 +126,28 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) > > int main(void) > { > - size_t pagesize = 0; > - int fd; > + size_t pagesize = psize(); > + unsigned int dio_align = get_dio_alignment(); Both could be const. > > ksft_print_header(); > > - /* Open the file to DIO */ > - fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664); > - if (fd < 0) > - ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno)); > - close(fd); Why can't we simply open the file once and pass the fd to run_dio_using_hugetlb()? fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664); if (fd < 0) ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno)); dio_align = get_dio_alignment(fd); if (dio_align <= 0) ksft_exit_skip("Unable to obtain DIO alignment: %s\n", strerror(errno)); ... run_dio_using_hugetlb(fd, 0, (pagesize * 3), dio_align); > - > /* Check if huge pages are free */ > if (!get_free_hugepages()) > ksft_exit_skip("No free hugepage, exiting\n"); > > ksft_set_plan(4); > > - /* Get base page size */ > - pagesize = psize(); > - > /* start and end is aligned to pagesize */ > - run_dio_using_hugetlb(0, (pagesize * 3)); > + run_dio_using_hugetlb(0, (pagesize * 3), dio_align); > > /* start is aligned but end is not aligned */ > - run_dio_using_hugetlb(0, (pagesize * 3) - (pagesize / 2)); > + run_dio_using_hugetlb(0, (pagesize * 3) - (pagesize / 2), dio_align); > > /* start is unaligned and end is aligned */ > - run_dio_using_hugetlb(pagesize / 2, (pagesize * 3)); > + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3), dio_align); > > /* both start and end are unaligned */ > - run_dio_using_hugetlb(pagesize / 2, (pagesize * 3) + (pagesize / 2)); > + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3) + (pagesize / 2), dio_align); > > ksft_finished(); > } -- Cheers, David