Messages in this thread | | | Subject | Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic | From | Konstantin Khlebnikov <> | Date | Wed, 7 Nov 2018 10:02:55 +0300 |
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On 06.11.2018 11:43, Arun KS wrote: > 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/ Could you point what exactly are you fixing with this set?
from v2:
> totalram_pages, zone->managed_pages and totalhigh_pages updates > are protected by managed_page_count_lock, but readers never care > about it. Convert these variables to atomic to avoid readers > potentially seeing a store tear.
This?
Aligned unsigned long almost always stored at once.
To make it completely correct you could replace
a += b;
with
WRITE_ONCE(a, a + b);
> > 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): >>>>>> 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(-)
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