[PATCH] mm: pmd dirty emulation in page fault handler

[Andreas Schwab]

On Dez 22 2016, Minchan Kim <minchan at kernel.org> wrote:

> From b3ec95c0df91ad113525968a4a6b53030fd0b48d Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan at 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@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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