[RFC][BUGFIX][PATCH 0/2] transhuge-memcg: some fixes (Re: Transparent Hugepage Support #25)

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

Hi.

Using Transparent Hugepage under memcg have some problems, mainly because
when a hugepage is being split, pc->mem_cgroup and pc->flags of tail pages
are not set. As a result, those pages are not linked to memcg's LRU, while
the usage remains as it is. This causes many problems: for example, the directory
can never be rmdir'ed, because the memcg's LRU of the group doesn't contain enough
pages to decrease the usage to 0.

These are trial patches to fix the problem(based on THP-25).

[1/2] is a simple bug fix, and can be folded into "memcg compound(commit d16259c1
at the http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git)".
[2/2] is a main patch.

Unfortunately, there seems to be some problems left, so I'm digging it and
need more tests.
Any comments are welcome.


Thanks,
Daisuke Nishimura.

On Fri, 21 May 2010 02:05:40 +0200, Andrea Arcangeli <aarcange@redhat.com> wrote:
> If you're running scientific applications, JVM or large gcc builds
> (see attached patch for gcc), and you want to run from 2.5% faster for
> kernel build (on bare metal), or 8% faster in translate.o of qemu (on
> bare metal), 15% faster or more with virt and Intel EPT/ AMD NPT
> (depending on the workload), you should apply and run the transparent
> hugepage support on your systems.
> 
> Awesome results have already been posted on lkml, if you test and
> benchmark it, please provide any positive/negative real-life result on
> lkml (or privately to me if you prefer). The more testing the better.
> 
> By running your scientific apps up to ~10% faster (or more if you use
> virt), and in turn by boosting the performance of the virtualized
> cloud, you will save energy. NOTE: it can cost memory in some cases,
> but this is why a madvise(MADV_HUGEPAGE) exists, so THP can be
> selectively enabled on the regions where the app knows there will be
> zero memory waste in boosting performance (like KVM).
> 
> If you have more memory than you need as filesystem cache you can
> choose "always" mode, while if you're ram constrained or you need as
> much filesystem cache as possible but you still want a CPU boost in
> the madvise regions without risking reducing the cache you should
> choose "madvise". All settings can be later tuned with sysfs after
> boot in /sys/kernel/mm/transparent_hugepage/ . You can monitor the
> THP utilization system-wide with "grep Anon /proc/meminfo".
> 
> http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git;a=shortlog
> http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git;a=shortlog;h=refs/heads/anon_vma_chain
> 
> first: git clone git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git
> or first: git clone --reference linux-2.6 git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git
> later: git fetch; git checkout -f origin/master
> or to run the new anon_vma_chain: git fetch; git checkout -f origin/anon_vma_chain
> 
> I am currently running the origin/anon_vma_chain branch on all my
> systems here (keeping master around only in case of troubles with the
> new anon-vma code).
> 
> The tree is rebased and git pull won't work.
> 
> http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34/transparent_hugepage-25/
> http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34/transparent_hugepage-25.gz
> http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34/transparent_hugepage-25-anon_vma_chain.gz
> 
> Diff #24 -> #25:
> 
>  b/exec-migrate-race-anon_vma-chain                       |  198 ++++++---------
> 
> Return to the cleaner fix that really allows the rmap_walk to succeed
> at all times (and it also allows migrate and split_huge_page at all
> times) without modifying the rmap_walk for this corner in execve. This
> is also more robust for the long term in case the user stack starts
> huge and we teach mremap to migrate without splitting hugepages (the
> stack may have to be splitted by some other operation in the
> VM).
> 
>  b/gfp_nomemalloc_wait                                    |   19 -
> 
> Fix: still clear ALLOC_CPUSET if the allocation is atomic.
> 
>  b/memory-compaction-anon-migrate-anon-vma-chain          |   49 +++
>  b/memory-compaction-anon-vma-refcount-anon-vma-chain     |  161 ++++++++----
>  b/memory-compaction-migrate-swapcache-anon-vma-chain     |  107 ++++++++
>  memory-compaction-anon-vma-share-refcount-anon-vma-chain |  166 ------------
> 
> Fix: the anon_vma_chain branch must use drop_anon_vma to be safe with
> the anon_vma->root->lock and avoid leaking root anon_vmas.
> 
>  b/pte_alloc_trans_splitting                              |   13 
> 
> use pmd_none instead of pmd_present in pte_alloc_map to be consistent
> with __pte_alloc (pmd_none shall be a bit faster too, and it's
> stricter too).
> 
>  b/transparent_hugepage                                   |   63 +++-
> 
> Race fix in initial huge pmd page fault (virtio-blk+THP was crashing
> the host by running "cp /dev/vda /dev/null" in guest, with a 6G ram
> guest and 4G ram + 4G swap host, immediately after host started
> swapping). I never reproduced it with any other workload apparently so
> it went unnoticed for a while (using the default ide emulation instead
> of virtio-blk also didn't show any problem at all probably because of
> different threading model or different timings). But it's not fixed.
> 
>  b/root_anon_vma-mm_take_all_locks                        |   81 ++++++
> 
> Prevent deadlock in root-anon-vma locking when registering in mmu
> notifier (i.e. starting kvm, but it only has been triggering with
> the -daemonize param for some reason, so it was unnoticed before as I
> normally run kvm in the foreground).
> 
> Diffstat:
> 
>  Documentation/cgroups/memory.txt      |    4 
>  Documentation/sysctl/vm.txt           |   25 
>  Documentation/vm/transhuge.txt        |  283 ++++
>  arch/alpha/include/asm/mman.h         |    2 
>  arch/mips/include/asm/mman.h          |    2 
>  arch/parisc/include/asm/mman.h        |    2 
>  arch/powerpc/mm/gup.c                 |   12 
>  arch/x86/include/asm/paravirt.h       |   23 
>  arch/x86/include/asm/paravirt_types.h |    6 
>  arch/x86/include/asm/pgtable-2level.h |    9 
>  arch/x86/include/asm/pgtable-3level.h |   23 
>  arch/x86/include/asm/pgtable.h        |  144 ++
>  arch/x86/include/asm/pgtable_64.h     |   14 
>  arch/x86/include/asm/pgtable_types.h  |    3 
>  arch/x86/kernel/paravirt.c            |    3 
>  arch/x86/kernel/vm86_32.c             |    1 
>  arch/x86/kvm/mmu.c                    |   26 
>  arch/x86/kvm/paging_tmpl.h            |    4 
>  arch/x86/mm/gup.c                     |   25 
>  arch/x86/mm/pgtable.c                 |   66 +
>  arch/xtensa/include/asm/mman.h        |    2 
>  drivers/base/node.c                   |    3 
>  fs/Kconfig                            |    2 
>  fs/exec.c                             |   37 
>  fs/proc/meminfo.c                     |   14 
>  fs/proc/page.c                        |   14 
>  include/asm-generic/mman-common.h     |    2 
>  include/asm-generic/pgtable.h         |  130 ++
>  include/linux/compaction.h            |   89 +
>  include/linux/gfp.h                   |   14 
>  include/linux/huge_mm.h               |  143 ++
>  include/linux/khugepaged.h            |   66 +
>  include/linux/kvm_host.h              |    4 
>  include/linux/memory_hotplug.h        |   14 
>  include/linux/migrate.h               |    2 
>  include/linux/mm.h                    |   92 +
>  include/linux/mm_inline.h             |   13 
>  include/linux/mm_types.h              |    3 
>  include/linux/mmu_notifier.h          |   40 
>  include/linux/mmzone.h                |   10 
>  include/linux/page-flags.h            |   36 
>  include/linux/rmap.h                  |   58 
>  include/linux/sched.h                 |    1 
>  include/linux/swap.h                  |    8 
>  include/linux/vmstat.h                |    4 
>  kernel/fork.c                         |   12 
>  kernel/futex.c                        |   67 -
>  kernel/sysctl.c                       |   25 
>  mm/Kconfig                            |   56 
>  mm/Makefile                           |    2 
>  mm/compaction.c                       |  620 +++++++++
>  mm/huge_memory.c                      | 2172 ++++++++++++++++++++++++++++++++++
>  mm/hugetlb.c                          |   69 -
>  mm/ksm.c                              |   77 -
>  mm/madvise.c                          |    8 
>  mm/memcontrol.c                       |   88 -
>  mm/memory-failure.c                   |    2 
>  mm/memory.c                           |  196 ++-
>  mm/memory_hotplug.c                   |   14 
>  mm/mempolicy.c                        |   14 
>  mm/migrate.c                          |   73 +
>  mm/mincore.c                          |  302 ++--
>  mm/mmap.c                             |   57 
>  mm/mprotect.c                         |   20 
>  mm/mremap.c                           |    8 
>  mm/page_alloc.c                       |  133 +-
>  mm/pagewalk.c                         |    1 
>  mm/rmap.c                             |  181 ++
>  mm/sparse.c                           |    4 
>  mm/swap.c                             |  116 +
>  mm/swap_state.c                       |    6 
>  mm/swapfile.c                         |    2 
>  mm/vmscan.c                           |   42 
>  mm/vmstat.c                           |  256 +++-
>  virt/kvm/iommu.c                      |    2 
>  virt/kvm/kvm_main.c                   |   39 
>  76 files changed, 5620 insertions(+), 522 deletions(-)