From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id E40216B0511 for ; Tue, 1 Aug 2017 06:06:26 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id 92so1639324wra.11 for ; Tue, 01 Aug 2017 03:06:26 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 79si933226wmn.71.2017.08.01.03.06.25 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 01 Aug 2017 03:06:25 -0700 (PDT) Date: Tue, 1 Aug 2017 11:06:23 +0100 From: Mel Gorman Subject: Re: [PATCH v5 3/3] Revert "mm: numa: defer TLB flush for THP migration as long as possible" Message-ID: <20170801100623.flalrk2t7jaik3fv@suse.de> References: <20170731164325.235019-1-namit@vmware.com> <20170731164325.235019-4-namit@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20170731164325.235019-4-namit@vmware.com> Sender: owner-linux-mm@kvack.org List-ID: To: Nadav Amit Cc: linux-mm@kvack.org, nadav.amit@gmail.com, riel@redhat.com, luto@kernel.org, Minchan Kim , Sergey Senozhatsky On Mon, Jul 31, 2017 at 09:43:25AM -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 > Cc: Minchan Kim > Cc: Sergey Senozhatsky > Cc: Andy Lutomirski > Cc: Rik van Riel > Signed-off-by: Nadav Amit Acked-by: Mel Gorman -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org