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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772105694; 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=8OsjUNu05V/Xcz8HI7pnG5Up/ePNSaNnSj1ALtPKgps=; b=QzYEVMogdec0mY0J3RwU6Gr0HY5yw0g0PC/NnZW/DkMBCuL1u6KkUPmfl0LnrwBZt3mQvH 6feN36V2Wav1NYWbEYKn+KdkhTLakwltwaJjj6dePky67MgNDAo4NhXA6gniUjonuoiq0T kN0P5eVVcfWnMjq8z+u3t6YjpBzNfhE= 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 18/21] selftests/mm: add partial_mprotect test for change_pmd_range Date: Thu, 26 Feb 2026 03:23:47 -0800 Message-ID: <20260226113233.3987674-19-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-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5FA31140009 X-Stat-Signature: x44bqaazjpgkbr1psmyon17a616urtsy X-Rspam-User: X-HE-Tag: 1772105696-383853 X-HE-Meta: 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 k9l7mAkU 7aFpsmRZio+aTxKOlSxCxMEteaSVMxpITW+3W7EgH7oBX8nwIH8mhqFbAT12z7Kx4XkszlNJ4+OB4B58ysAzmI8FWtHZzUmLdZ9HhhAvPlZmMbaQi1kreyD4019eJhOIs5ooD7M34kRLsKfJgxJL/utsoNePDf8A+hAzd9U+DQcb7qgYUwcqBf4e2QXUJKmWmE/0YioWHKLX72WUVnGjyrK+jrlYNwOZng9PbrTNltdbU530dOCdF+8yqRw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add test for partial mprotect on THP which exercises change_pmd_range(). This verifies that partial mprotect correctly splits the PMD, applies protection only to the requested portion, and leaves the rest of the mapping writable. Signed-off-by: Usama Arif --- .../testing/selftests/mm/thp_pmd_split_test.c | 31 +++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/tools/testing/selftests/mm/thp_pmd_split_test.c b/tools/testing/selftests/mm/thp_pmd_split_test.c index 0f54ac04760d5..4944a5a516da9 100644 --- a/tools/testing/selftests/mm/thp_pmd_split_test.c +++ b/tools/testing/selftests/mm/thp_pmd_split_test.c @@ -146,4 +146,35 @@ TEST_F(thp_pmd_split, partial_munmap) self->split_pmd_failed_before); } +/* + * Partial mprotect on THP (change_pmd_range) + * + * Tests that partial mprotect of a THP correctly splits the PMD and + * applies protection only to the requested portion. This exercises + * the mprotect path which now handles split failures. + */ +TEST_F(thp_pmd_split, partial_mprotect) +{ + 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"); + + /* Partial mprotect - make middle page read-only */ + ret = mprotect((char *)self->aligned + self->pagesize, self->pagesize, PROT_READ); + ASSERT_EQ(ret, 0); + + /* Verify we can still write to non-protected pages */ + ptr[0] = 0xDD; + ptr[self->pmdsize - 1] = 0xEE; + + ASSERT_EQ(ptr[0], (unsigned char)0xDD); + ASSERT_EQ(ptr[self->pmdsize - 1], (unsigned char)0xEE); + + log_and_check_pmd_split(_metadata, self->split_pmd_before, + self->split_pmd_failed_before); +} + TEST_HARNESS_MAIN -- 2.47.3