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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 47BCC140007 X-Stat-Signature: 5sbqprhczoobzjsazj9hyrbtz3hbadfq X-Rspam-User: X-HE-Tag: 1765897023-377770 X-HE-Meta: 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 S7gzlvWX UKoCMfNHcQJtD/Cd9duomKdEBhbA/sDgeSt9/no2EBrgFzMsgzBvpuw+OFjJyNEuE2RPesj6skQz+fTY4Vlt/tHv5wVy3UGcxZEjzl527wtVuPEQTE0xar8AvOQrY42XOnNk1yHnHfSuwve4+5jOJWxRtt7vZXOqnBDC5DKfGeLRqvp7qQM1qTqMl4V4JRHxZym0SF5NOwOxSjrTg2jnA9+N7cTR40/mD6M+E7V8D21UyPhyLxPELkRpMww== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 16/12/2025 14:26, Kevin Brodsky wrote: > One of the pagemap_ioctl tests attempts to fault in pages by > memcpy()'ing them to an unused buffer. This probably worked > originally, but since commit 46036188ea1f ("selftests/mm: build with > -O2") the compiler is free to optimise away that unused buffer and > the memcpy() with it. As a result there might not be any resident > page in the mapping and the test may fail. > > We don't need to copy all that memory anyway. Just fault in every > page by forcing the compiler to read the first byte. > > Cc: Usama Anjum > Signed-off-by: Kevin Brodsky > --- > tools/testing/selftests/mm/pagemap_ioctl.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c b/tools/testing/selftests/mm/pagemap_ioctl.c > index 2cb5441f29c7..67a7a3705604 100644 > --- a/tools/testing/selftests/mm/pagemap_ioctl.c > +++ b/tools/testing/selftests/mm/pagemap_ioctl.c > @@ -1056,7 +1056,6 @@ int sanity_tests(void) > struct page_region *vec; > char *mem, *fmem; > struct stat sbuf; > - char *tmp_buf; > > /* 1. wrong operation */ > mem_size = 10 * page_size; > @@ -1167,8 +1166,9 @@ int sanity_tests(void) > if (fmem == MAP_FAILED) > ksft_exit_fail_msg("error nomem %d %s\n", errno, strerror(errno)); > > - tmp_buf = malloc(sbuf.st_size); > - memcpy(tmp_buf, fmem, sbuf.st_size); > + /* Fault in every page by reading the first byte */ > + for (i = 0; i < sbuf.st_size; i += page_size) > + (void)*(volatile char *)(fmem + i); We have FORCE_READ() in vm_util.h for this. Perhaps that would be better? > > ret = pagemap_ioctl(fmem, sbuf.st_size, vec, vec_size, 0, 0, > 0, PAGEMAP_NON_WRITTEN_BITS, 0, PAGEMAP_NON_WRITTEN_BITS);