linux-kernel - [PATCH v1 0/4] powernv/memtrace: don't abuse memory hot(un)plug infrastructure for memory allocations

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Message-Id: <20201029162718.29910-1-david@redhat.com>
Date:   Thu, 29 Oct 2020 17:27:14 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Hocko <mhocko@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        Mike Rapoport <rppt@...nel.org>,
        Oscar Salvador <osalvador@...e.de>,
        Paul Mackerras <paulus@...ba.org>,
        Rashmica Gupta <rashmica.g@...il.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: [PATCH v1 0/4] powernv/memtrace: don't abuse memory hot(un)plug infrastructure for memory allocations

powernv/memtrace is the only in-kernel user that rips out random memory
it never added (doesn't own) in order to allocate memory without a
linear mapping. Let's stop abusing memory hot(un)plug infrastructure for
that - use alloc_contig_pages() for allocating memory and remove the
linear mapping manually.

The original idea was discussed in:
 https://lkml.kernel.org/r/48340e96-7e6b-736f-9e23-d3111b915b6e@redhat.com

I only tested allocations briefly via QEMU TCG - see patch #4 for more
details.

David Hildenbrand (4):
  powerpc/mm: factor out creating/removing linear mapping
  powerpc/mm: print warning in arch_remove_linear_mapping()
  powerpc/mm: remove linear mapping if __add_pages() fails in
    arch_add_memory()
  powernv/memtrace: don't abuse memory hot(un)plug infrastructure for
    memory allocations

 arch/powerpc/mm/mem.c                     |  48 +++++---
 arch/powerpc/platforms/powernv/Kconfig    |   8 +-
 arch/powerpc/platforms/powernv/memtrace.c | 134 ++++++++--------------
 include/linux/memory_hotplug.h            |   3 +
 4 files changed, 86 insertions(+), 107 deletions(-)

-- 
2.26.2