Messages in this thread | | | Date | Fri, 11 Aug 2017 12:50:15 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v6 3/7] Revert "mm: numa: defer TLB flush for THP migration as long as possible" |
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On Tue, Aug 01, 2017 at 05:08:14PM -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.
FWIW this Changelog sucks arse; you completely fail to explain the broken ordering.
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