Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic

[Arun KS <arunks@codeaurora.org>]

On 2018-11-06 14:07, Konstantin Khlebnikov wrote:
> 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.

Few instances which can race with hot add. Please see below,
https://patchwork.kernel.org/patch/10627521/

Regards,
Arun

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