selftests/powerpc: Test the THP bug we fixed in the previous commit

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Ellerman 2014-05-28 18:21:18 +10:00 committed by Benjamin Herrenschmidt
parent 09567e7fd4
commit d34b661b10
3 changed files with 91 additions and 1 deletions

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@ -13,7 +13,7 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR
export CC CFLAGS
TARGETS = pmu copyloops
TARGETS = pmu copyloops mm
endif

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@ -0,0 +1,18 @@
noarg:
$(MAKE) -C ../
PROGS := hugetlb_vs_thp_test
all: $(PROGS)
$(PROGS): ../harness.c
run_tests: all
@-for PROG in $(PROGS); do \
./$$PROG; \
done;
clean:
rm -f $(PROGS)
.PHONY: all run_tests clean

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@ -0,0 +1,72 @@
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include "utils.h"
/* This must match the huge page & THP size */
#define SIZE (16 * 1024 * 1024)
static int test_body(void)
{
void *addr;
char *p;
addr = (void *)0xa0000000;
p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (p != MAP_FAILED) {
/*
* Typically the mmap will fail because no huge pages are
* allocated on the system. But if there are huge pages
* allocated the mmap will succeed. That's fine too, we just
* munmap here before continuing.
*/
munmap(addr, SIZE);
}
p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (p == MAP_FAILED) {
printf("Mapping failed @ %p\n", addr);
perror("mmap");
return 1;
}
/*
* Either a user or kernel access is sufficient to trigger the bug.
* A kernel access is easier to spot & debug, as it will trigger the
* softlockup or RCU stall detectors, and when the system is kicked
* into xmon we get a backtrace in the kernel.
*
* A good option is:
* getcwd(p, SIZE);
*
* For the purposes of this testcase it's preferable to spin in
* userspace, so the harness can kill us if we get stuck. That way we
* see a test failure rather than a dead system.
*/
*p = 0xf;
munmap(addr, SIZE);
return 0;
}
static int test_main(void)
{
int i;
/* 10,000 because it's a "bunch", and completes reasonably quickly */
for (i = 0; i < 10000; i++)
if (test_body())
return 1;
return 0;
}
int main(void)
{
return test_harness(test_main, "hugetlb_vs_thp");
}