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Tue, 30 Jun 2026 10:45:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782816347; bh=81g9nQCWE+mnZNEbv5idLZmIKGtoPWn06b20cZHWlKg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bBs7FIc1czEHhj/ZjXSRYfnmdenzMd0iZwQBLMVNsCj2HRNguS3J9h/O2PxR+1LLi /+mJZ5MfYWh7xdlxCo2M8/zXi6rT5+HpZ7rwMZq0V8BLGGLFygjfEghsKlziDn3q1k RdYbfdyaOeHo6CRgDeDx6eN9H+50Bk/B32to6oA/aZjpcOwSoBWTuYzWaco/gUHJ/S QyXMxFU7TCYEBlUX+nCDCPbSVE58Fq2FLgtS0MIs8Jv5CNR6j/7h3iqsBSbZ/7+6Jh iLKFEQq7QuMUiAtoYdwOwB8pEKrbFjoO25CREqNbaGODe2k4FRqxzeEvqOqXki5Aw7 3WVuJz8mLXjIA== Message-ID: Date: Tue, 30 Jun 2026 12:45:42 +0200 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] selftests/mm: handle EINVAL when configuring gigantic hugepages To: Sayali Patil , Andrew Morton , Shuah Khan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Ritesh Harjani Cc: Zi Yan , Michal Hocko , Oscar Salvador , Lorenzo Stoakes , Dev Jain , Liam.Howlett@oracle.com, linuxppc-dev@lists.ozlabs.org, Miaohe Lin , Venkat Rao Bagalkote References: <3d394c8cd59fe380d4e2d13b051544f241918f07.1782811071.git.sayalip@linux.ibm.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 On 6/30/26 11:32, Sayali Patil wrote: > Some MM selftests attempt to configure the amount of > HugeTLB pages of different sizes by writing to nr_hugepages. > > PowerPC hash MMU pSeries systems advertise gigantic hugepage sizes > but do not support runtime allocation of such pages, writes > to the corresponding nr_hugepages file fail with -EINVAL. > This causes the test to bail out even though the failure is due > to a platform limitation rather than the > functionality being tested. > > Treat -EINVAL from the sysfs write as a skipped configuration request > and continue running the test instead of failing. > > Before patch: > ------------------------- > running ./hugetlb-madvise > ------------------------- > TAP version 13 > 1..1 > [INFO] detected hugetlb page size: 16777216 KiB > [INFO] detected hugetlb page size: 16384 KiB > ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb > Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0 > Bail out! /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages > write(0) failed: Invalid argument > Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 > [FAIL] > > After patch: > ------------------------- > running ./hugetlb-madvise > ------------------------- > TAP version 13 > 1..1 > [INFO] detected hugetlb page size: 16777216 KiB > [INFO] detected hugetlb page size: 16384 KiB > ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb > Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0 > /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages > write(0) failed: Invalid argument > [PASS] > > Fixes: 27477b28b74f ("selftests/mm: hugepage_settings: add APIs to get and set nr_hugepages") > Signed-off-by: Sayali Patil > --- > .../testing/selftests/mm/hugepage_settings.c | 32 ++++++++++++++++++- > .../testing/selftests/mm/hugepage_settings.h | 1 + > 2 files changed, 32 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/mm/hugepage_settings.c b/tools/testing/selftests/mm/hugepage_settings.c > index 2eab2110ac6a..ce38ae3da01a 100644 > --- a/tools/testing/selftests/mm/hugepage_settings.c > +++ b/tools/testing/selftests/mm/hugepage_settings.c > @@ -422,6 +422,36 @@ static void hugetlb_sysfs_path(char *buf, size_t buflen, > size / 1024, attr); > } > > +void hugetlb_write_num(const char *path, unsigned long num) > +{ > + int fd, saved_errno; > + ssize_t numwritten; > + char buf[21]; > + > + sprintf(buf, "%lu", num); > + > + fd = open(path, O_WRONLY); > + if (fd == -1) > + ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno)); > + > + numwritten = write(fd, buf, strlen(buf)); > + saved_errno = errno; > + close(fd); > + errno = saved_errno; > + > + /* Treat EINVAL as a skipped configuration (e.g., unsupported gigantic pages) */ > + if (numwritten < 0 && errno == EINVAL) { > + ksft_print_msg("%s write(%s) failed: %s\n", path, buf, strerror(errno)); Should we even print anything here? Rather confusing. It's just like we cannot allocate anything (no memory). In general, you are copy-pasting a lot of write_num()+write_file() content, which is really suboptimal. All you want is an option for write_num -> write_file to skip on -EINVAL, correct? There are not that many write_num / write_file users ... -- Cheers, David