Important note :
According to the man page
"On success, process_vm_readv() returns the number of bytes read and
process_vm_writev() returns the number of bytes written. This return
value may be less than the total number of requested bytes, if a
partial read/write occurred. (Partial transfers apply at the
granularity of iovec elements. These system calls won't perform a
partial transfer that splits a single iovec element.)"
So since we use a single iovec element, the returned size should either
be 0 or size, and the do loop should not be needed here.
We tried on various Linux kernels with size > 2 GB, and surprisingly,
the returned value is always 0x7ffff000 (fwiw, it happens to be the size
of the larger number of pages that fits a signed 32 bits integer).
We do not know whether this is a bug from the kernel, the libc or even
the man page, but for the time being, we do as is process_vm_readv() could
return any value.
Thanks Heiko Bauke for the bug report.
Refs. open-mpi/ompi#4829
Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>
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