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selftest/vm: verify mmap addr in mremap_test

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[ Upstream commit 9c85a9bae267f6b5e5e374d0d023bbbe9db096d3 ]

Avoid calling mmap with requested addresses that are less than the
system's mmap_min_addr.  When run as root, mmap returns EACCES when
trying to map addresses < mmap_min_addr.  This is not one of the error
codes for the condition to retry the mmap in the test.

Rather than arbitrarily retrying on EACCES, don't attempt an mmap until
addr > vm.mmap_min_addr.

Add a munmap call after an alignment check as the mappings are retained
after the retry and can reach the vm.max_map_count sysctl.

Link: https://lkml.kernel.org/r/20220420215721.4868-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sidhartha Kumar 2022-04-21 16:35:49 -07:00 committed by Greg Kroah-Hartman
parent 680e982ae8
commit e8b9989597
1 changed files with 29 additions and 0 deletions
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29
tools/testing/selftests/vm/mremap_test.c
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@ -66,6 +66,35 @@ enum {
.expect_failure = should_fail \
}
/* Returns mmap_min_addr sysctl tunable from procfs */
static unsigned long long get_mmap_min_addr(void)
{
FILE *fp;
int n_matched;
static unsigned long long addr;
if (addr)
return addr;
fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
if (fp == NULL) {
ksft_print_msg("Failed to open /proc/sys/vm/mmap_min_addr: %s\n",
strerror(errno));
exit(KSFT_SKIP);
}
n_matched = fscanf(fp, "%llu", &addr);
if (n_matched != 1) {
ksft_print_msg("Failed to read /proc/sys/vm/mmap_min_addr: %s\n",
strerror(errno));
fclose(fp);
exit(KSFT_SKIP);
}
fclose(fp);
return addr;
}
/*
* Returns false if the requested remap region overlaps with an
* existing mapping (e.g text, stack) else returns true.