Petr Vorel <pvorel@xxxxxxx> writes: > Hi Stefan, > >> This disables the "smart scan" KSM feature to make sure that the volatile >> count remains at 0. > >> Signed-off-by: Stefan Roesch <devkernel.io> > nit: you forgot 'shr@' > Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx> > Thanks, will be fixed with the next version. >> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> >> Closes: https://lore.kernel.org/oe-lkp/202311161132.13d8ce5a-oliver.sang@xxxxxxxxx >> --- >> testcases/kernel/mem/lib/mem.c | 4 ++++ >> 1 file changed, 4 insertions(+) > >> diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c >> index fbfeef026..ef274a3ac 100644 >> --- a/testcases/kernel/mem/lib/mem.c >> +++ b/testcases/kernel/mem/lib/mem.c >> @@ -454,6 +454,9 @@ void create_same_memory(int size, int num, int unit) >> {'a', size*MB}, {'a', size*MB}, {'d', size*MB}, {'d', size*MB}, >> }; > >> + /* Disable smart scan for correct volatile counts. */ >> + SAFE_FILE_PRINTF(PATH_KSM "smart_scan", "0"); > NOTE, this fails on the systems without /sys/kernel/mm/ksm/smart_scan: > > mem.c:458: TBROK: Failed to open FILE '/sys/kernel/mm/ksm/smart_scan' for writing: EACCES (13) > > NOTE, we normally handle the setup like this in test setup function. > > But new API has .save_restore which is more robust for tasks like this. > It's already used in ksm01.c, you need just to add this line: > {"/sys/kernel/mm/ksm/smart_scan", "0", TST_SR_SKIP}, > I'll add it with the next version > (instead of both SAFE_FILE_PRINTF) > > See: > https://github.com/linux-test-project/ltp/wiki/C-Test-API#127-saving--restoring-procsys-values > > I wonder if ksm01.c is the only ksm test which needs to disable this. > Other tests will also need it. They also use the create_same_memory() function. > also nit: there is a wrong indent (spaces instead of tabs), please be consistent > with the file content. > > NOTE: while this fixes problem on 6.7.0-rc1-2.g86e46c2-default (openSUSE), > it does not fixes other problem on 6.5.10 on Debian (16 errors like these below): > > mem.c:252: TFAIL: pages_shared is not 2 but 5038. > mem.c:252: TFAIL: pages_sharing is not 98302 but 593629. > mem.c:252: TFAIL: pages_volatile is not 0 but 391. > mem.c:252: TFAIL: pages_unshared is not 0 but 149157. > > I have no idea if this is a real bug which needs to be fixed or test false > positive to be fixed, or whether the problem has already been fixed in newer > kernels. > This is a different problem. "Smart scan was introduced with 6.7" >> + >> ps = sysconf(_SC_PAGE_SIZE); >> pages = MB / ps; > >> @@ -526,6 +529,7 @@ void create_same_memory(int size, int num, int unit) > >> tst_res(TINFO, "stop KSM."); >> SAFE_FILE_PRINTF(PATH_KSM "run", "0"); >> + SAFE_FILE_PRINTF(PATH_KSM "smart_scan", "1"); > nit: Again, wrong indent. You could have seen it also in the generated patch. > > Kind regards, > Petr > >> final_group_check(0, 0, 0, 0, 0, 0, size * pages * num); > >> while (waitpid(-1, &status, 0) > 0) > >> base-commit: 8c89ef3d451087ed6e18750bd5eedd10e5ab3d2e
