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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772105711; 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=NNFcsrTCJuN3pq1P0jDB1SWfqOIjrkZR0u7eCL/hrlc=; b=KI9SLjROFcSirL2mTS5OuZAfOP+ehi28WMw/ahTS4caHqgegRKvYlaWKxelk0oDyR0nsl5 /QixN5IwhA0UcIZAWfR1y/OvtYWnl7Ph+KBswIu2u7tJvUJmFOgV/00DoRlyspgzic/ovd xV36dvYGWz99ZyLasi42ArQFEIfukOw= From: Usama Arif To: Andrew Morton , david@kernel.org, lorenzo.stoakes@oracle.com, 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: [RFC v2 21/21] selftests/mm: add madv_dontneed_partial test Date: Thu, 26 Feb 2026 03:23:50 -0800 Message-ID: <20260226113233.3987674-22-usama.arif@linux.dev> In-Reply-To: <20260226113233.3987674-1-usama.arif@linux.dev> References: <20260226113233.3987674-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 7CDB9180006 X-Rspamd-Server: rspam02 X-Stat-Signature: 3u6oforjz6c3k8ukjt6tqo43qyusys9d X-HE-Tag: 1772105713-219832 X-HE-Meta: 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 vib325TK wXosa87psl9YJvNGCu/7sC4EEP/l5r3lclf5eM2VISGHI3UPNWzkLwJ+VoS0dKWOU/58vLZAgKBS7TT96Fgmw5qUp1oyvEhTlneGO4ztjxjn9hun0oywSC8RQ5vOdv8rU2/GVsfzo0K+1TOLi5xOHGGfvburtD3EYykbsOWoO0KxBlmT05ySGsPL0WCqsR5xcKnrZbZ4HxMXEX0kKTggJQCNBHvF/WYVo0qbLKTeGE5pTXDiQxybAoFkh+w== 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 -- 2.47.3