lib: kunit_iov_iter: fix test fail on powerpc

Increase buffer size to accommodate machines with 64K PAGE_SIZE.

Link: https://lore.kernel.org/20260421070707.992873-1-lk@c--e.de
Fixes: 0913b75 ("lib: kunit_iov_iter: add tests for extract_iter_to_sg")
Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
Reported-by: David Gow <davidgow@google.com>
Closes: https://lore.kernel.org/34a81ec2-af84-465d-9b5e-7bb5bf01680f@davidgow.net
Tested-by: David Gow <davidgow@google.com>
Tested-by: Josh Law <joshlaw48@gmail.com>
Reviewed-by: Josh Law <joshlaw48@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Christian A. Ehrhardt

lib/tests/kunit_iov_iter.c

@@ -1128,7 +1128,7 @@ static void __init iov_kunit_iter_to_sg_kvec(struct kunit *test)
 	struct kvec kvec;
 	size_t bufsize;
 
-	bufsize = 0x100000;
+	bufsize = 0x200000;
 	iov_kunit_iter_to_sg_init(test, bufsize, false, &data);
 
 	kvec.iov_base = data.buffer;
@@ -1146,7 +1146,7 @@ static void __init iov_kunit_iter_to_sg_bvec(struct kunit *test)
 	struct bio_vec *bvec;
 	struct iov_iter iter;
 
-	bufsize = 0x100000;
+	bufsize = 0x200000;
 	iov_kunit_iter_to_sg_init(test, bufsize, false, &data);
 
 	bvec = kunit_kmalloc_array(test, data.npages, sizeof(*bvec),
@@ -1173,7 +1173,7 @@ static void __init iov_kunit_iter_to_sg_folioq(struct kunit *test)
 	struct iov_iter iter;
 	size_t bufsize;
 
-	bufsize = 0x100000;
+	bufsize = 0x200000;
 	iov_kunit_iter_to_sg_init(test, bufsize, false, &data);
 
 	folioq = iov_kunit_create_folioq(test);
@@ -1190,7 +1190,7 @@ static void __init iov_kunit_iter_to_sg_xarray(struct kunit *test)
 	struct iov_iter iter;
 	size_t bufsize;
 
-	bufsize = 0x100000;
+	bufsize = 0x200000;
 	iov_kunit_iter_to_sg_init(test, bufsize, false, &data);
 
 	xarray = iov_kunit_create_xarray(test);
@@ -1206,7 +1206,7 @@ static void __init iov_kunit_iter_to_sg_ubuf(struct kunit *test)
 	struct iov_iter iter;
 	size_t bufsize;
 
-	bufsize = 0x100000;
+	bufsize = 0x200000;
 	iov_kunit_iter_to_sg_init(test, bufsize, true, &data);
 
 	iov_iter_ubuf(&iter, READ, data.ubuf, bufsize);