LTP syscall "migrate_pages03" case will be failed due to infinite loop and timeout when any qemu guest is launched in v6.8 - v6.10 kernel about ltp

[xupengfe]

I added some debug code and executed migrate_pages03 in the host and infinite loop when any qemu guest is launched:

# ./migrate_pages03 
tst_test.c:1806: TINFO: LTP version: 20240524-92-gd39edc7fb
tst_test.c:1652: TINFO: Timeout per run is 0h 05m 30s
migrate_pages03.c:97: TINFO: wait_ksmd_full_scan start: orig_ksm_run:-1
ksm_helper.c:18: TINFO: SAFE_FILE_SCANF start
ksm_helper.c:19: TINFO: /sys/kernel/mm/ksm/full_scans, lineno:19, fmt:%lu
ksm_helper.c:19: TINFO: exp_convs:1
ksm_helper.c:19: TINFO: Expected 1 conversions got 1 FILE '/sys/kernel/mm/ksm/full_scans'
ksm_helper.c:31: TINFO: at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:35: TINFO: -> Before SAFE_FILE_SCANF count:1, at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:36: TINFO: /sys/kernel/mm/ksm/full_scans, lineno:36, fmt:%lu
ksm_helper.c:36: TINFO: exp_convs:1
ksm_helper.c:36: TINFO: Expected 1 conversions got 1 FILE '/sys/kernel/mm/ksm/full_scans'
ksm_helper.c:37: TINFO: -> After SAFE_FILE_SCANF at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:35: TINFO: -> Before SAFE_FILE_SCANF count:2, at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:36: TINFO: /sys/kernel/mm/ksm/full_scans, lineno:36, fmt:%lu
ksm_helper.c:36: TINFO: exp_convs:1
ksm_helper.c:36: TINFO: Expected 1 conversions got 1 FILE '/sys/kernel/mm/ksm/full_scans'
ksm_helper.c:37: TINFO: -> After SAFE_FILE_SCANF at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:35: TINFO: -> Before SAFE_FILE_SCANF count:3, at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:36: TINFO: /sys/kernel/mm/ksm/full_scans, lineno:36, fmt:%lu
ksm_helper.c:36: TINFO: exp_convs:1
ksm_helper.c:36: TINFO: Expected 1 conversions got 1 FILE '/sys/kernel/mm/ksm/full_scans'
ksm_helper.c:37: TINFO: -> After SAFE_FILE_SCANF at_least_one_full_scan:880,  full_scans:877
ksm_helper.c:35: TINFO: -> Before SAFE_FILE_SCANF count:4, at_least_one_full_scan:880,  full_scans:877

Debug code:

diff --git a/lib/safe_file_ops.c b/lib/safe_file_ops.c
index 63ae2dbbe..db9d4b1be 100644
--- a/lib/safe_file_ops.c
+++ b/lib/safe_file_ops.c
@@ -126,7 +126,7 @@ void safe_file_scanf(const char *file, const int lineno,
        int exp_convs, ret;
 
        f = fopen(path, "r");
-
+       tst_resm_(file, lineno, TINFO, "%s, lineno:%d, fmt:%s", path, lineno, fmt);
        if (f == NULL) {
                tst_brkm_(file, lineno, TBROK | TERRNO, cleanup_fn,
                        "Failed to open FILE '%s' for reading", path);
@@ -134,7 +134,6 @@ void safe_file_scanf(const char *file, const int lineno,
        }
 
        exp_convs = tst_count_scanf_conversions(fmt);
-
        va_start(va, fmt);
        ret = vfscanf(f, fmt, va);
        va_end(va);
@@ -145,6 +144,8 @@ void safe_file_scanf(const char *file, const int lineno,
                return;
        }
 
+       tst_resm_(file, lineno, TINFO, "Expected %i conversions got %i FILE '%s'",
+                       exp_convs, ret, path);
        if (ret != exp_convs) {
                tst_brkm_(file, lineno, TBROK, cleanup_fn,
                        "Expected %i conversions got %i FILE '%s'",
diff --git a/testcases/kernel/lib/ksm_helper.c b/testcases/kernel/lib/ksm_helper.c
index 586a0d1ee..ab424cca0 100644
--- a/testcases/kernel/lib/ksm_helper.c
+++ b/testcases/kernel/lib/ksm_helper.c
@@ -30,7 +30,9 @@ void wait_ksmd_full_scan(void)
        while (full_scans < at_least_one_full_scan) {
                sleep(1);
                count++;
+               tst_res(TINFO, "-> Before SAFE_FILE_SCANF count:%d, at_least_one_full_scan:%ld,  full_scans:%ld", count, at_least_one_full_scan, full_scans);
                SAFE_FILE_SCANF(PATH_KSM "full_scans", "%lu", &full_scans);
+               tst_res(TINFO, "-> After SAFE_FILE_SCANF at_least_one_full_scan:%ld,  full_scans:%ld", at_least_one_full_scan, full_scans);
        }
 
        tst_res(TINFO, "ksm daemon takes %ds to run two full scans", count);
diff --git a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c
index 4d3299b61..fdd7b398f 100644
--- a/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c
+++ b/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c
@@ -72,7 +72,6 @@ static void setup(void)
        set_bit(new_nodes[1], nodes[1], 1);
 
        page_size = getpagesize();
-
        for (n = 0; n < N_PAGES; n++) {
                test_pages[n] = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE | PROT_EXEC,
                                          MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
@@ -95,6 +94,7 @@ static void setup(void)
 
        SAFE_FILE_SCANF(PATH_KSM "run", "%d", &orig_ksm_run);
        SAFE_FILE_PRINTF(PATH_KSM "run", "%d", 1);
+       tst_res(TINFO, "wait_ksmd_full_scan start: orig_ksm_run:%d", orig_ksm_run);
        wait_ksmd_full_scan();
 }
 
@@ -118,6 +118,7 @@ static void migrate_test(void)
 {
        int loop, i, ret;
 
+       tst_res(TINFO, "SAFE_SETEUID");
        SAFE_SETEUID(ltpuser->pw_uid);
        for (loop = 0; loop < N_LOOPS; loop++) {
                i = loop % 2;

Thanks!

[xupengfe]

One more thing, could we skip the ltp/testcases/kernel/syscalls/migrate_pages/migrate_pages03.c
wait_ksmd_full_scan(); function? Because even we remove this step checking, this case could be passed. Thanks!