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Subject[kselftests] compaction_test is blocked
Date
Hi

kselftests is integrated Intel 0Day project.
Sometimes we found compaction_test is blocked for more than 1 hours until i kill it.

Try to figure out where it is running, i added some log to this case.

the test log is like:
-------------------
[ 111.750543] main: 248
[ 111.750544]-
[ 111.750821] check_compaction: 98
[ 111.750822]-
[ 111.751102] check_compaction: 105
[ 111.751103]-
[ 111.751362] check_compaction: 111
[ 111.751363]-
[ 111.751621] check_compaction: 118
[ 111.751622]-
[ 111.751879] check_compaction: 123
[ 111.751880]-
-------------------
118 fprintf(stderr, "%s: %d\n", __func__, __LINE__);
119 lseek(fd, 0, SEEK_SET);
120
121 /* Request a large number of huge pages. The Kernel will allocate
122 as much as it can */
123 fprintf(stderr, "%s: %d\n", __func__, __LINE__); <<<======== the last line we can catch.
124 if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) { <<<<============ blocking position
125 perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
126 goto close_fd;
127 }
128
129 lseek(fd, 0, SEEK_SET);
130
131 fprintf(stderr, "%s: %d\n", __func__, __LINE__);
132 if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
133 perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
134 goto close_fd;
135 }
-------------------

According to above log and code, it most likely it is blocking at the writing operation.

my environment is like:
OS: debian
kernel: v4.15
model: Ivytown Ivy Bridge-EP
nr_cpu: 48
memory: 64G


NOTE: 0Day can reproduce this issue in 20% on 0Day.

Anybody can help have a look?

Thanks
Zhjian



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