215ba78115
When MAP_HUGETLB memory is unmapped, the length must be hugepage aligned, otherwise it fails with -EINVAL. All tests currently behave correctly, but it's better to explcitly test the return value for completeness and document the requirement, especially if users copy map_hugetlb.c as a sample implementation. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joern Engel <joern@logfs.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Eric B Munson <emunson@akamai.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
77 lines
1.7 KiB
C
77 lines
1.7 KiB
C
#include <stdio.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include "utils.h"
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/* This must match the huge page & THP size */
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#define SIZE (16 * 1024 * 1024)
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static int test_body(void)
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{
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void *addr;
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char *p;
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addr = (void *)0xa0000000;
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p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
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MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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if (p != MAP_FAILED) {
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/*
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* Typically the mmap will fail because no huge pages are
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* allocated on the system. But if there are huge pages
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* allocated the mmap will succeed. That's fine too, we just
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* munmap here before continuing. munmap() length of
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* MAP_HUGETLB memory must be hugepage aligned.
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*/
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if (munmap(addr, SIZE)) {
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perror("munmap");
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return 1;
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}
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}
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p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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if (p == MAP_FAILED) {
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printf("Mapping failed @ %p\n", addr);
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perror("mmap");
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return 1;
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}
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/*
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* Either a user or kernel access is sufficient to trigger the bug.
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* A kernel access is easier to spot & debug, as it will trigger the
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* softlockup or RCU stall detectors, and when the system is kicked
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* into xmon we get a backtrace in the kernel.
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*
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* A good option is:
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* getcwd(p, SIZE);
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*
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* For the purposes of this testcase it's preferable to spin in
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* userspace, so the harness can kill us if we get stuck. That way we
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* see a test failure rather than a dead system.
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*/
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*p = 0xf;
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munmap(addr, SIZE);
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return 0;
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}
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static int test_main(void)
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{
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int i;
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/* 10,000 because it's a "bunch", and completes reasonably quickly */
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for (i = 0; i < 10000; i++)
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if (test_body())
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return 1;
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return 0;
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}
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int main(void)
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{
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return test_harness(test_main, "hugetlb_vs_thp");
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}
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