* [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary [not found] <cover.1721293231.git.pengfei.xu@intel.com> @ 2024-07-18 9:03 ` Pengfei Xu 2024-07-18 10:06 ` Li Wang 0 siblings, 1 reply; 4+ messages in thread From: Pengfei Xu @ 2024-07-18 9:03 UTC (permalink / raw) To: ltp; +Cc: feij.fnst Remove wait_ksmd_full_scan() check because it's not a necessary step for migrate_pages03 syscall test: 1. KSM(kernel samepage merging) could be enabled and it is optional for migrate_pages syscall testing. 2. When server launched any qemu guest, wait_ksmd_full_scan() will in infinite loop due to /sys/kernel/mm/ksm/full_scans number would not increase anymore, and migrate_pages03 will failed with timeout reason. After removed wait_ksmd_full_scan(), migrate_pages03 could pass without issue. Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> --- testcases/kernel/syscalls/migrate_pages/migrate_pages03.c | 1 - 1 file changed, 1 deletion(-) diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c index 4d3299b61..f514ed10c 100644 --- a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c +++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c @@ -95,7 +95,6 @@ static void setup(void) SAFE_FILE_SCANF(PATH_KSM "run", "%d", &orig_ksm_run); SAFE_FILE_PRINTF(PATH_KSM "run", "%d", 1); - wait_ksmd_full_scan(); } static void cleanup(void) -- 2.43.0 -- Mailing list info: https://lists.linux.it/listinfo/ltp ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary 2024-07-18 9:03 ` [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary Pengfei Xu @ 2024-07-18 10:06 ` Li Wang 2024-07-18 10:09 ` Li Wang 0 siblings, 1 reply; 4+ messages in thread From: Li Wang @ 2024-07-18 10:06 UTC (permalink / raw) To: Pengfei Xu; +Cc: feij.fnst, ltp Pengfei Xu <pengfei.xu@intel.com> wrote: Remove wait_ksmd_full_scan() check because it's not a necessary step for > migrate_pages03 syscall test: > 1. KSM(kernel samepage merging) could be enabled and it is optional for > migrate_pages syscall testing. > The wait_ksmd_full_scan guarantees the actual merging happens then test can migrate those merged KSM pages to reproduce the regression panic in kernel commit 4b0ece6fa0167b. So this is a necessary configuration before testing. > 2. When server launched any qemu guest, wait_ksmd_full_scan() will in > infinite loop due to /sys/kernel/mm/ksm/full_scans number would not > increase anymore, and migrate_pages03 will failed with timeout reason. > After removed wait_ksmd_full_scan(), migrate_pages03 could pass without > issue. Yes, this timeout problem likely exists. That is the KSM design which can't avoid "unrelated" page merging happening in the background. But removing the wait_ksmd_full_scan might not be a good approach IMHO. Cc @Andrea Arcangeli <aarcange@redhat.com> if he has good suggestions on the test. > Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> > --- > testcases/kernel/syscalls/migrate_pages/migrate_pages03.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > index 4d3299b61..f514ed10c 100644 > --- a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > +++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > @@ -95,7 +95,6 @@ static void setup(void) > > SAFE_FILE_SCANF(PATH_KSM "run", "%d", &orig_ksm_run); > SAFE_FILE_PRINTF(PATH_KSM "run", "%d", 1); > - wait_ksmd_full_scan(); > } > > static void cleanup(void) > -- > 2.43.0 > > > -- > Mailing list info: https://lists.linux.it/listinfo/ltp > > -- Regards, Li Wang -- Mailing list info: https://lists.linux.it/listinfo/ltp ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary 2024-07-18 10:06 ` Li Wang @ 2024-07-18 10:09 ` Li Wang 2024-07-19 1:29 ` Pengfei Xu 0 siblings, 1 reply; 4+ messages in thread From: Li Wang @ 2024-07-18 10:09 UTC (permalink / raw) To: Pengfei Xu; +Cc: Andrea Arcangeli, feij.fnst, ltp Sorry, forgot to cc Andrea Arcangeli in the last reply. On Thu, Jul 18, 2024 at 6:06 PM Li Wang <liwang@redhat.com> wrote: > Pengfei Xu <pengfei.xu@intel.com> wrote: > > Remove wait_ksmd_full_scan() check because it's not a necessary step for >> migrate_pages03 syscall test: >> 1. KSM(kernel samepage merging) could be enabled and it is optional for >> migrate_pages syscall testing. >> > > The wait_ksmd_full_scan guarantees the actual merging happens then test > can migrate those merged KSM pages to reproduce the regression panic in > kernel commit 4b0ece6fa0167b. > > So this is a necessary configuration before testing. > > >> 2. When server launched any qemu guest, wait_ksmd_full_scan() will in >> infinite loop due to /sys/kernel/mm/ksm/full_scans number would not >> increase anymore, and migrate_pages03 will failed with timeout reason. >> After removed wait_ksmd_full_scan(), migrate_pages03 could pass without >> issue. > > > Yes, this timeout problem likely exists. That is the KSM design which can't > avoid "unrelated" page merging happening in the background. > But removing the wait_ksmd_full_scan might not be a good approach IMHO. > > Cc @Andrea Arcangeli <aarcange@redhat.com> if he has good suggestions on > the test. > > >> Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> >> --- >> testcases/kernel/syscalls/migrate_pages/migrate_pages03.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c >> b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c >> index 4d3299b61..f514ed10c 100644 >> --- a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c >> +++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c >> @@ -95,7 +95,6 @@ static void setup(void) >> >> SAFE_FILE_SCANF(PATH_KSM "run", "%d", &orig_ksm_run); >> SAFE_FILE_PRINTF(PATH_KSM "run", "%d", 1); >> - wait_ksmd_full_scan(); >> } >> >> static void cleanup(void) >> -- >> 2.43.0 >> >> >> -- >> Mailing list info: https://lists.linux.it/listinfo/ltp >> >> > > -- > Regards, > Li Wang > -- Regards, Li Wang -- Mailing list info: https://lists.linux.it/listinfo/ltp ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary 2024-07-18 10:09 ` Li Wang @ 2024-07-19 1:29 ` Pengfei Xu 0 siblings, 0 replies; 4+ messages in thread From: Pengfei Xu @ 2024-07-19 1:29 UTC (permalink / raw) To: Li Wang; +Cc: Andrea Arcangeli, feij.fnst, ltp Hi Li Wang and Andrea Arcangeli, On 2024-07-18 at 18:09:56 +0800, Li Wang wrote: > Sorry, forgot to cc Andrea Arcangeli in the last reply. > > > On Thu, Jul 18, 2024 at 6:06 PM Li Wang <liwang@redhat.com> wrote: > > > Pengfei Xu <pengfei.xu@intel.com> wrote: > > > > Remove wait_ksmd_full_scan() check because it's not a necessary step for > >> migrate_pages03 syscall test: > >> 1. KSM(kernel samepage merging) could be enabled and it is optional for > >> migrate_pages syscall testing. > >> > > > > The wait_ksmd_full_scan guarantees the actual merging happens then test > > can migrate those merged KSM pages to reproduce the regression panic in > > kernel commit 4b0ece6fa0167b. > > > > So this is a necessary configuration before testing. I did not consider the above situation. Is it possible to improve wait_ksmd_full_scan() to handle the scenario described in point 2? > > > > > >> 2. When server launched any qemu guest, wait_ksmd_full_scan() will in > >> infinite loop due to /sys/kernel/mm/ksm/full_scans number would not > >> increase anymore, and migrate_pages03 will failed with timeout reason. > >> After removed wait_ksmd_full_scan(), migrate_pages03 could pass without > >> issue. > > > > > > Yes, this timeout problem likely exists. That is the KSM design which can't > > avoid "unrelated" page merging happening in the background. > > But removing the wait_ksmd_full_scan might not be a good approach IMHO. Yes, thanks for above background info sharing! Best Regards, Thank you! > > > > Cc @Andrea Arcangeli <aarcange@redhat.com> if he has good suggestions on > > the test. > > > > > >> Signed-off-by: Pengfei Xu <pengfei.xu@intel.com> > >> --- > >> testcases/kernel/syscalls/migrate_pages/migrate_pages03.c | 1 - > >> 1 file changed, 1 deletion(-) > >> > >> diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > >> b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > >> index 4d3299b61..f514ed10c 100644 > >> --- a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > >> +++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c > >> @@ -95,7 +95,6 @@ static void setup(void) > >> > >> SAFE_FILE_SCANF(PATH_KSM "run", "%d", &orig_ksm_run); > >> SAFE_FILE_PRINTF(PATH_KSM "run", "%d", 1); > >> - wait_ksmd_full_scan(); > >> } > >> > >> static void cleanup(void) > >> -- > >> 2.43.0 > >> > >> > >> -- > >> Mailing list info: https://lists.linux.it/listinfo/ltp > >> > >> > > > > -- > > Regards, > > Li Wang > > > > > -- > Regards, > Li Wang -- Mailing list info: https://lists.linux.it/listinfo/ltp ^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-07-18 9:03 ` [LTP] [PATCH v1 1/1] migrate_pages03: remove wait_ksmd_full_scan() check because it's not necessary Pengfei Xu
2024-07-18 10:06 ` Li Wang
2024-07-18 10:09 ` Li Wang
2024-07-19 1:29 ` Pengfei Xu
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