Is MADV_HWPOISON supposed to work only on faulted-in pages?

[Jan Stancek <jstancek@xxxxxxxxxx>]

Hi,

code below (and LTP madvise07 [1]) doesn't produce SIGBUS,
unless I touch/prefault page before call to madvise().

Is this expected behavior?

Thanks,
Jan

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise07.c

-------------------- 8< --------------------
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>

int main(void)
{
	void *mem = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
			MAP_ANONYMOUS | MAP_PRIVATE /*| MAP_POPULATE*/,
			-1, 0);

	if (mem == MAP_FAILED)
		exit(1);

	if (madvise(mem, getpagesize(), MADV_HWPOISON) == -1)
		exit(1);

	*((char *)mem) = 'd';

	return 0;
}
-------------------- 8< --------------------

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