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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777384188; bh=t30QIMEMwddaP+f8CyRmCqUIYCZU4C7eqdDikOzltg0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Kz0llVJQJ8iMvWNY+15gZD3TzXDP3x7+IxK4Hbht2eEZyBAzbR50uA+2lB7amIMkh BCzKE2Q6AHuCF0xILmCYuUlNRdSyytnm+VGGWr4sP3BPqbqU/5EoP4PCFfc595/0AO EUC6DN+y90P9Al682BHV4g39BZa4y88uxflaoNxUgIqiTdxhoWF7WiDHfNBDS4Ga0W BInPAISl7GuovWyUVVA9L8jgybg7mXPhqArjwDJVTOex1L2qRx8+Xi8pVsyFNAtx18 wXUvTx2TJljJNkyVImnOV6z6CknVKqvQQd8zEIOkfx3Tg6gVpVj4YtpkwhMsnfnurK 5TQlxK0N4PoUQ== Message-ID: Date: Tue, 28 Apr 2026 15:49:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] selftests/mm: khugepaged: initialize file contents via mmap To: Vineet Agarwal , akpm@linux-foundation.org, ljs@kernel.org, shuah@kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260428133138.88802-1-agarwal.vineet2006@gmail.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-Stat-Signature: 86baedhfc3cmgw15saz6nh76m71dwhet X-Rspam-User: X-Rspamd-Queue-Id: AE7C24000B X-Rspamd-Server: rspam07 X-HE-Tag: 1777384189-997957 X-HE-Meta: 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 mfgRApBn Bvb8uqTVgj5vbgBaz470ffDB9Sq5gW+9DzJA0av6lDuv62BCILFGRkeLLRcPklp3rn83juVKmr9s9ROHebjJt7nGih/kR7sjCL2xqYbGh4nTife390Aw8L0V/2136tIhI1x1rSpR936GBFySSUENVjDPLYL8z2c9+2WD3m/GXHt3xtQhRG37n070Pt2x61OMLjlcycBdfnWfxPfmDWHERwHdebJTMcZz+yIs1K1KGO9sF+CneTHqmslfPgbbL+BX1fYicJ+8cgGn8efvTy9Cy6XR/oDJ6dZhYW77jXc4ntFltjWP7jRq9GJ5U+vXQ+0czuglYNh48iTBqz3OCKRq0g2VUDgyUV4dn/pu3E0iVDTKk2IacahJRvsAX7rVSziRpKEnq5rcsVuoUaxWz6uH+cUVvHQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/28/26 15:31, Vineet Agarwal wrote: > file_setup_area() currently allocates anonymous memory, fills it, > and writes it into the backing file used for collapse testing. > > Instead of copying data through write(), resize the file with > ftruncate(), map it directly with MAP_SHARED, and initialize the > mapped area in place. > > This simplifies the setup path and avoids the need for explicit > partial write handling. > > Signed-off-by: Vineet Agarwal > > v3 -> v4: > - Restore unrelated blank line removal > - Restore original close()/munmap() ordering > --- > tools/testing/selftests/mm/khugepaged.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c > index 3fe7ef04ac62..6e929a484a1b 100644 > --- a/tools/testing/selftests/mm/khugepaged.c > +++ b/tools/testing/selftests/mm/khugepaged.c > @@ -381,9 +381,19 @@ static void *file_setup_area(int nr_hpages) > } > > size = nr_hpages * hpage_pmd_size; > - p = alloc_mapping(nr_hpages); > + if (ftruncate(fd, size)) { > + perror("ftruncate()"); > + close(fd); > + exit(EXIT_FAILURE); > + } > + p = mmap(BASE_ADDR, size, PROT_READ | PROT_WRITE, > + MAP_SHARED, fd, 0); > + if (p == MAP_FAILED || p != BASE_ADDR) { p != BASE_ADDR is sufficient as it includes p == MAP_FAILED. > + perror("mmap()"); > + close(fd); > + exit(EXIT_FAILURE); > + } > fill_memory(p, 0, size); > - write(fd, p, size); > close(fd); > munmap(p, size); > success("OK"); Thanks! Acked-by: David Hildenbrand (Arm) -- Cheers, David