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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 101A7180005 X-Stat-Signature: 6gcpp9gjanftx5yroccu11y6my7o8dk3 X-Rspam-User: X-HE-Tag: 1769156234-712310 X-HE-Meta: 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 koKPGTdb lj1diMyrYxLlD5NMcmK3gtr+eXrq5dtltJU8yhfyCrXFJ+sJ2p7niO7LoEAaXroXdNb334AzbU0Gw4HMMeWQzwJC5bPKHHqBHVVKs8YQam7NXPXCR/3OUqnU8ChTX4jdEvggDfogqojpwAC5YtiDAQA0Fa0yoZA/emyUAE4s/+PiK5y1VyOGEyPKhtJ9thN2xEMNompBwI6tL4UtBfoMryaLDmmJ8qldA4565NHfGQjoKsgLAaJhFA8xjhH3Pny0wWsNyQEChxMV5s3pLVK9gkAG5CcRRjpXqtzWZB3em3Ijo+4Q= 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 22/01/2026 23:18, David Hildenbrand (Red Hat) wrote: > On 1/22/26 18:02, Kevin Brodsky wrote: >> Many cow tests rely on FORCE_READ() to populate pages. Introduce a >> helper to make sure that the pages are actually populated, and fail >> otherwise. >> >> Suggested-by: David Hildenbrand (Red Hat) >> Signed-off-by: Kevin Brodsky >> --- >>   tools/testing/selftests/mm/cow.c | 43 ++++++++++++++++++++++++-------- >>   1 file changed, 33 insertions(+), 10 deletions(-) >> >> diff --git a/tools/testing/selftests/mm/cow.c >> b/tools/testing/selftests/mm/cow.c >> index 83b3563be26b..d9c69c04b67d 100644 >> --- a/tools/testing/selftests/mm/cow.c >> +++ b/tools/testing/selftests/mm/cow.c >> @@ -75,6 +75,18 @@ static bool range_is_swapped(void *addr, size_t size) >>       return true; >>   } >>   +static bool populate_page_checked(char *addr) >> +{ >> +    bool ret; >> + >> +    FORCE_READ(*addr); >> +    ret = pagemap_is_populated(pagemap_fd, addr); >> +    if (!ret) >> +        ksft_print_msg("Failed to populate page\n"); >> + >> +    return ret; >> +} > > LGTM. > > On second thought, this primarily catches if someone breaks > FORCE_READ() ... which hopefully doesn't happen that often? ;) > > Because if the read succeeded, surely there must be something in the > page tables.  Indeed, one would hope so! The check doesn't hurt either though (especially since we already have the pagemap fd around). - Kevin