On Mon, 2017-07-31 at 09:43 -0700, Nadav Amit wrote:

While deferring TLB flushes is a good practice, the reverted patch
caused pending TLB flushes to be checked while the page-table lock is
not taken. As a result, in architectures with weak memory model
(PPC),
Linux may miss a memory-barrier, miss the fact TLB flushes are
pending,
and cause (in theory) a memory corruption.

Since the alternative of using smp_mb__after_unlock_lock() was
considered a bit open-coded, and the performance impact is expected
to
be small, the previous patch is reverted.

This reverts commit b0943d61b8fa420180f92f64ef67662b4f6cc493.

Suggested-by: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <redacted>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Rik van Riel <redacted>
Signed-off-by: Nadav Amit <redacted>

Acked-by: Rik van Riel <redacted>

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