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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1774577789; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6/HdPBhl1cpZOUmiZuBTWaeHIDSWjs3qo4yxLZnBGpA=; b=LBA+DGA7C1hpEc4UK/USzbeWl9ofYAB9golUoHkRx3arz+0f+tCFBPShuiq8sFBcmjRcuj BkqIUVWSZWrzlncJMS6q2HSKiSIKaHundpnJFyYH9WZp0Dq8jBzWfRFloYOIU6zqnN8+4q hwvlj8SU2eHG55dpFcr7cLa/cO3P9xE= From: Usama Arif To: Andrew Morton , david@kernel.org, Lorenzo Stoakes , willy@infradead.org, linux-mm@kvack.org Cc: fvdl@google.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, maddy@linux.ibm.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, linux-s390@vger.kernel.org, Usama Arif Subject: [v3 24/24] selftests/mm: add madv_dontneed_partial test Date: Thu, 26 Mar 2026 19:09:06 -0700 Message-ID: <20260327021403.214713-25-usama.arif@linux.dev> In-Reply-To: <20260327021403.214713-1-usama.arif@linux.dev> References: <20260327021403.214713-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2A66518000D X-Stat-Signature: 6hei19nwj73jjpn48bebec4dxcpoy55d X-HE-Tag: 1774577790-143935 X-HE-Meta: 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 gz5Vb0ad 5JmGDy7yDPnufglVfDLChjomS8qO5koDX1seq6e4KoL8fpdX4mHz+eX5xvJFgRGEjYNsaLjyhmGqzT1sgpyuake6YYJ3DejPaKqpI00shoJ+UJM6VvyGvDX7mSILF6u6gqkX0GfGuw0FiK2psEEteOePZA86iQaMKzFEHexLN9q2ObJEqg8r6rTWGc3HprM8AR4cLkws47rEv65tyeq2u+iJIcptw6pLlXE+GRbBBYST9gPsHB6S3GmzNbg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add test for partial MADV_DONTNEED on THP. This verifies that MADV_DONTNEED correctly triggers a PMD split, discards only the requested page (which becomes zero-filled), and preserves data in the surrounding pages. Signed-off-by: Usama Arif --- .../testing/selftests/mm/thp_pmd_split_test.c | 34 +++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/tools/testing/selftests/mm/thp_pmd_split_test.c b/tools/testing/selftests/mm/thp_pmd_split_test.c index 1f29296759a5b..060ca1e341b75 100644 --- a/tools/testing/selftests/mm/thp_pmd_split_test.c +++ b/tools/testing/selftests/mm/thp_pmd_split_test.c @@ -253,4 +253,38 @@ TEST_F(thp_pmd_split, partial_mremap) self->split_pmd_failed_before); } +/* + * MADV_DONTNEED on THP + * + * Tests that MADV_DONTNEED on a partial THP correctly handles + * the PMD split and discards only the requested pages. + */ +TEST_F(thp_pmd_split, partial_madv_dontneed) +{ + volatile unsigned char *ptr = (volatile unsigned char *)self->aligned; + int ret; + + ret = allocate_thp(self->aligned, self->pmdsize); + if (ret) + SKIP(return, "Failed to allocate THP"); + + /* Write pattern */ + memset(self->aligned, 0xDD, self->pmdsize); + + /* Partial MADV_DONTNEED - discard middle page */ + ret = madvise((char *)self->aligned + self->pagesize, self->pagesize, MADV_DONTNEED); + ASSERT_EQ(ret, 0); + + /* Verify non-discarded pages still have data */ + ASSERT_EQ(ptr[0], (unsigned char)0xDD); + ASSERT_EQ(ptr[2 * self->pagesize], (unsigned char)0xDD); + ASSERT_EQ(ptr[self->pmdsize - 1], (unsigned char)0xDD); + + /* Discarded page should be zero */ + ASSERT_EQ(ptr[self->pagesize], (unsigned char)0x00); + + log_and_check_pmd_split(_metadata, self->split_pmd_before, + self->split_pmd_failed_before); +} + TEST_HARNESS_MAIN -- 2.52.0