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Ehrhardt" , linux-kernel@vger.kernel.org, Andrew Morton , David Howells CC: Kees Cook , Petr Mladek , David Gow Subject: Re: [PATCH v2 1/3] lib: kunit_iov_iter: Improve error detection User-Agent: Thunderbird for Android In-Reply-To: <20260324203453.810499-2-lk@c--e.de> References: <20260324203453.810499-1-lk@c--e.de> <20260324203453.810499-2-lk@c--e.de> Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External On 24 March 2026 20:34:51 GMT, "Christian A=2E Ehrhardt" wr= ote: >In the kunit_iov_iter test prevent the kernel buffer from >being a single physically contiguous region=2E > >Additionally, make sure that the test pattern written to >a page in the buffer depends on the offset of the page within >the buffer=2E > >Cc: David Howells >Cc: Andrew Morton >Signed-off-by: Christian A=2E Ehrhardt >--- > lib/tests/kunit_iov_iter=2Ec | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > >diff --git a/lib/tests/kunit_iov_iter=2Ec b/lib/tests/kunit_iov_iter=2Ec >index bb847e5010eb=2E=2Ec42b9235f57a 100644 >--- a/lib/tests/kunit_iov_iter=2Ec >+++ b/lib/tests/kunit_iov_iter=2Ec >@@ -13,6 +13,7 @@ > #include > #include > #include >+#include > #include > MODULE_DESCRIPTION("iov_iter testing"); >@@ -37,7 +38,7 @@ static const struct kvec_test_range kvec_test_ranges[] = =3D { >=20 > static inline u8 pattern(unsigned long x) > { >- return x & 0xff; >+ return (u8)x + (u8)(x >> 8) + (u8)(x >> 16); Suggestion: You could use bitwise XOR if you like return (x ^ (x >> 8) ^ (x >> 16)) & 0xff; > } >=20 > static void iov_kunit_unmap(void *data) >@@ -52,6 +53,7 @@ static void *__init iov_kunit_create_buffer(struct kuni= t *test, > struct page **pages; > unsigned long got; > void *buffer; >+ unsigned int i; Nit: unsigned long is probably better here >=20 > pages =3D kunit_kcalloc(test, npages, sizeof(struct page *), GFP_KERNEL= ); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pages); >@@ -62,6 +64,9 @@ static void *__init iov_kunit_create_buffer(struct kuni= t *test, > release_pages(pages, got); > KUNIT_ASSERT_EQ(test, got, npages); > } >+ /* Make sure that we don't get a physically contiguous buffer=2E */ >+ for (i =3D 0; i < npages / 4; ++i) I do really like this method, but This may not be achievable, but if npages ever pass less than 4, it could = evaluate to 0 >+ swap(pages[i], pages[i + npages/2]); Nit: The spacing is a bit odd, you could change it to swap(pages[i], pages[i + npages / 2]); >=20 > buffer =3D vmap(pages, npages, VM_MAP | VM_MAP_PUT_PAGES, PAGE_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buffer); This doesn't affect my reviewed by, but just some things to clean up V/R Josh Law