[LTP] [PATCH] syscalls/migrate_pages03: skip migratition of shared pages

[Li Wang]

On Fri, Nov 30, 2018 at 12:29 AM Jan Stancek <jstancek@redhat.com> wrote:
>
> Fixes: #431
>
> Migrating shared pages (as root) includes also executable pages
> (glibc, etc.) Kernel might need to invalidate icache, which can
> be an expensive operation on some architectures (arm64).
>
> This test is repeating migration thousands of times, and because
> migration (and icache flush) runs for each page, it all stacks
> up and test is hitting a timeout.
>
> It's enough for this reproducer to migrate pages it allocates
> and merges (via KSM), so do the migration as unprivileged user
> and we can avoid the overhead of migrating everything. Such
> scenario is already covered by migrate_pages02.

I'm OK to drop privileges before calling migrate_pages() in this
testcase, but if we can start a new topic in LKML for more discussion
that would be better?

>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>

Reviewed-by: Li Wang <liwang@redhat.com>

--
Regards,
Li Wang