On Dez 22 2016, Minchan Kim [off-list ref] wrote:

From b3ec95c0df91ad113525968a4a6b53030fd0b48d Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Thu, 22 Dec 2016 23:43:49 +0900
Subject: [PATCH v2] mm: pmd dirty emulation in page fault handler

Andreas reported [1] made a test in jemalloc hang in THP mode in arm64.
http://lkml.kernel.org/r/mvmmvfy37g1.fsf at hawking.suse.de

The problem is page fault handler supports only accessed flag emulation
for THP page of SW-dirty/accessed architecture.

This patch enables dirty-bit emulation for those architectures.
Without it, MADV_FREE makes application hang by repeated fault forever.

[1] b8d3c4c3009d, mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called

Successfully tested a backport to 4.9.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab at suse.de
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