[LTP] [PATCH v2] madvise06: Allow for kmem and memsw counters being disabled

[Richard Palethorpe]

These may be missing in which case we can not read them for diagnostic
info or set the swap limit to a value which is known to be large
enough. However if there is no swap counter then there is no swap
limit, so we just try to set the limit if the counter exists.

Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
Reviewed-by: Li Wang <liwang@redhat.com>
---

V2: Check if the memsw limit exists before writing to it. This
    replaces another patch which removed it altogether.

 testcases/kernel/syscalls/madvise/madvise06.c | 29 ++++++++++++-------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/testcases/kernel/syscalls/madvise/madvise06.c b/testcases/kernel/syscalls/madvise/madvise06.c
index 817faae39..7e9e9ef84 100644
--- a/testcases/kernel/syscalls/madvise/madvise06.c
+++ b/testcases/kernel/syscalls/madvise/madvise06.c
@@ -65,14 +65,16 @@ static void check_path(const char *path)
 }
 
 #define READ_CGMEM(item)						\
-	({long tst_rval;						\
-	  SAFE_FILE_LINES_SCANF(MNT_NAME"/"GROUP_NAME"/memory."item, 	\
-				"%ld",					\
-				&tst_rval);				\
+	({long tst_rval = 0;						\
+	  const char *cgpath = MNT_NAME"/"GROUP_NAME"/memory."item;	\
+	  if (!access(cgpath, R_OK))					\
+		  SAFE_FILE_LINES_SCANF(cgpath, "%ld", &tst_rval);	\
 	  tst_rval;})
 
 static void meminfo_diag(const char *point)
 {
+	long rval;
+
 	FILE_PRINTF("/proc/sys/vm/stat_refresh", "1");
 	tst_res(TINFO, "%s", point);
 	tst_res(TINFO, "\tSwap: %ld Kb",
@@ -83,10 +85,14 @@ static void meminfo_diag(const char *point)
 		SAFE_READ_MEMINFO("Cached:") - init_cached);
 	tst_res(TINFO, "\tcgmem.usage_in_bytes: %ld Kb",
 		READ_CGMEM("usage_in_bytes") / 1024);
-	tst_res(TINFO, "\tcgmem.memsw.usage_in_bytes: %ld Kb",
-		READ_CGMEM("memsw.usage_in_bytes") / 1024);
-	tst_res(TINFO, "\tcgmem.kmem.usage_in_bytes: %ld Kb",
-		READ_CGMEM("kmem.usage_in_bytes") / 1024);
+
+	rval = READ_CGMEM("memsw.usage_in_bytes") / 1024;
+	if (rval)
+		tst_res(TINFO, "\tcgmem.memsw.usage_in_bytes: %ld Kb", rval);
+
+	rval = READ_CGMEM("kmem.usage_in_bytes") / 1024;
+	if (rval)
+		tst_res(TINFO, "\tcgmem.kmem.usage_in_bytes: %ld Kb", rval);
 }
 
 static void setup(void)
@@ -124,8 +130,11 @@ static void setup(void)
 	SAFE_FILE_PRINTF("/proc/self/oom_score_adj", "%d", -1000);
 	SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.limit_in_bytes", "%ld\n",
 			 MEM_LIMIT);
-	SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.memsw.limit_in_bytes", "%ld\n",
-			 MEMSW_LIMIT);
+
+	if (!access(MNT_NAME"/"GROUP_NAME"/memory.memsw.limit_in_bytes", W_OK)) {
+		SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.memsw.limit_in_bytes",
+				 "%ld\n", MEMSW_LIMIT);
+	}
 	SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.swappiness", "60");
 	SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/tasks", "%d\n", getpid());
 
-- 
2.29.1