linux-kernel - Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh

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Date:   Tue, 6 Nov 2018 11:37:02 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     Arun KS <arunks@...eaurora.org>
Cc:     keescook@...omium.org, minchan@...nel.org, getarunks@...il.com,
        gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
        mhocko@...nel.org, vbabka@...e.cz, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, julia.lawall@...6.fr
Subject: Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and
 managed pages to atomic



On 06.11.2018 11:30, Arun KS wrote:
> On 2018-11-06 13:47, Konstantin Khlebnikov wrote:
>> On 06.11.2018 8:38, Arun KS wrote:
>>> Any comments?
>>
>> Looks good.
>> Except unclear motivation behind this change.
>> This should be in comment of one of patch.
> 
> totalram_pages, zone->managed_pages and totalhigh_pages are sometimes modified outside managed_page_count_lock. Hence convert these variable 
> to atomic to avoid readers potentially seeing a store tear.

So, this is just theoretical issue or splat from sanitizer.
After boot memory online\offline are strictly serialized by rw-semaphore.

> 
> Will update the comment.
> 
> Regards,
> Arun
> 
>>
>> Reviewed-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
>>
>>>
>>> Regards,
>>> Arun
>>>
>>> On 2018-10-26 16:30, Arun KS wrote:
>>>> This series convert totalram_pages, totalhigh_pages and
>>>> zone->managed_pages to atomic variables.
>>>>
>>>> The patch was comiple tested on x86(x86_64_defconfig & i386_defconfig)
>>>> on tip of linux-mmotm. And memory hotplug tested on arm64, but on an
>>>> older version of kernel.
>>>>
>>>> Arun KS (4):
>>>>   mm: Fix multiple evaluvations of totalram_pages and managed_pages
>>>>   mm: Convert zone->managed_pages to atomic variable
>>>>   mm: convert totalram_pages and totalhigh_pages variables to atomic
>>>>   mm: Remove managed_page_count spinlock
>>>>
>>>>  arch/csky/mm/init.c                           |  4 +-
>>>>  arch/powerpc/platforms/pseries/cmm.c          | 10 ++--
>>>>  arch/s390/mm/init.c                           |  2 +-
>>>>  arch/um/kernel/mem.c                          |  3 +-
>>>>  arch/x86/kernel/cpu/microcode/core.c          |  5 +-
>>>>  drivers/char/agp/backend.c                    |  4 +-
>>>>  drivers/gpu/drm/amd/amdkfd/kfd_crat.c         |  2 +-
>>>>  drivers/gpu/drm/i915/i915_gem.c               |  2 +-
>>>>  drivers/gpu/drm/i915/selftests/i915_gem_gtt.c |  4 +-
>>>>  drivers/hv/hv_balloon.c                       | 19 +++----
>>>>  drivers/md/dm-bufio.c                         |  2 +-
>>>>  drivers/md/dm-crypt.c                         |  2 +-
>>>>  drivers/md/dm-integrity.c                     |  2 +-
>>>>  drivers/md/dm-stats.c                         |  2 +-
>>>>  drivers/media/platform/mtk-vpu/mtk_vpu.c      |  2 +-
>>>>  drivers/misc/vmw_balloon.c                    |  2 +-
>>>>  drivers/parisc/ccio-dma.c                     |  4 +-
>>>>  drivers/parisc/sba_iommu.c                    |  4 +-
>>>>  drivers/staging/android/ion/ion_system_heap.c |  2 +-
>>>>  drivers/xen/xen-selfballoon.c                 |  6 +--
>>>>  fs/ceph/super.h                               |  2 +-
>>>>  fs/file_table.c                               |  7 +--
>>>>  fs/fuse/inode.c                               |  2 +-
>>>>  fs/nfs/write.c                                |  2 +-
>>>>  fs/nfsd/nfscache.c                            |  2 +-
>>>>  fs/ntfs/malloc.h                              |  2 +-
>>>>  fs/proc/base.c                                |  2 +-
>>>>  include/linux/highmem.h                       | 28 ++++++++++-
>>>>  include/linux/mm.h                            | 27 +++++++++-
>>>>  include/linux/mmzone.h                        | 15 +++---
>>>>  include/linux/swap.h                          |  1 -
>>>>  kernel/fork.c                                 |  5 +-
>>>>  kernel/kexec_core.c                           |  5 +-
>>>>  kernel/power/snapshot.c                       |  2 +-
>>>>  lib/show_mem.c                                |  2 +-
>>>>  mm/highmem.c                                  |  4 +-
>>>>  mm/huge_memory.c                              |  2 +-
>>>>  mm/kasan/quarantine.c                         |  2 +-
>>>>  mm/memblock.c                                 |  6 +--
>>>>  mm/memory_hotplug.c                           |  4 +-
>>>>  mm/mm_init.c                                  |  2 +-
>>>>  mm/oom_kill.c                                 |  2 +-
>>>>  mm/page_alloc.c                               | 71 +++++++++++++--------------
>>>>  mm/shmem.c                                    |  7 +--
>>>>  mm/slab.c                                     |  2 +-
>>>>  mm/swap.c                                     |  2 +-
>>>>  mm/util.c                                     |  2 +-
>>>>  mm/vmalloc.c                                  |  4 +-
>>>>  mm/vmstat.c                                   |  4 +-
>>>>  mm/workingset.c                               |  2 +-
>>>>  mm/zswap.c                                    |  4 +-
>>>>  net/dccp/proto.c                              |  7 +--
>>>>  net/decnet/dn_route.c                         |  2 +-
>>>>  net/ipv4/tcp_metrics.c                        |  2 +-
>>>>  net/netfilter/nf_conntrack_core.c             |  7 +--
>>>>  net/netfilter/xt_hashlimit.c                  |  5 +-
>>>>  net/sctp/protocol.c                           |  7 +--
>>>>  security/integrity/ima/ima_kexec.c            |  2 +-
>>>>  58 files changed, 195 insertions(+), 144 deletions(-)