From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: proc: fix map_files test on F29 F29 bans mapping first 64KB even for root making test fail. Iterate from address 0 until mmap() works. Gentoo (root): openat(AT_FDCWD, "/dev/zero", O_RDONLY) = 3 mmap(NULL, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0 Gentoo (non-root): openat(AT_FDCWD, "/dev/zero", O_RDONLY) = 3 mmap(NULL, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EPERM (Operation not permitted) mmap(0x1000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x1000 F29 (root): openat(AT_FDCWD, "/dev/zero", O_RDONLY) = 3 mmap(NULL, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x1000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x2000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x3000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x4000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x5000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x6000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x7000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x8000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x9000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xa000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xb000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xc000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xd000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xe000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0xf000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = -1 EACCES (Permission denied) mmap(0x10000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x10000 Now all proc tests succeed on F29 if run as root, at last! Link: http://lkml.kernel.org/r/20190414123612.GB12971@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/proc/proc-self-map-files-002.c | 20 +++++----- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/tools/testing/selftests/proc/proc-self-map-files-002.c~proc-fix-map_files-test-on-f29 +++ a/tools/testing/selftests/proc/proc-self-map-files-002.c @@ -46,12 +46,9 @@ static void fail(const char *fmt, unsign int main(void) { - const unsigned int PAGE_SIZE = sysconf(_SC_PAGESIZE); -#ifdef __arm__ - unsigned long va = 2 * PAGE_SIZE; -#else - unsigned long va = 0; -#endif + const int PAGE_SIZE = sysconf(_SC_PAGESIZE); + const unsigned long va_max = 1UL << 32; + unsigned long va; void *p; int fd; unsigned long a, b; @@ -60,10 +57,13 @@ int main(void) if (fd == -1) return 1; - p = mmap((void *)va, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE|MAP_FIXED, fd, 0); - if (p == MAP_FAILED) { - if (errno == EPERM) - return 4; + for (va = 0; va < va_max; va += PAGE_SIZE) { + p = mmap((void *)va, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE|MAP_FIXED, fd, 0); + if (p == (void *)va) + break; + } + if (va == va_max) { + fprintf(stderr, "error: mmap doesn't like you\n"); return 1; } _
