/proc/meminfo says VmallocUsed is 0. So where are my kernel modules stored?











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I thought the code for kernel modules was stored in a vmalloc() allocation? (In fact I'm sure the kernel code is using vmalloc(), not kvmalloc()). So why does /proc/meminfo say I have no zero VmallocUsed ?



$ grep Vmalloc /proc/meminfo

VmallocTotal:   34359738367 kB

VmallocUsed:           0 kB

VmallocChunk:          0 kB

$ lsmod|head

Module                  Size  Used by

vfio_mdev              16384  0

mdev                   20480  1 vfio_mdev

vfio_iommu_type1       28672  0

vfio                   32768  2 vfio_mdev,vfio_iommu_type1

kvm_intel             237568  0

kvm                   737280  1 kvm_intel

irqbypass              16384  1 kvm

dummy                  16384  0

binfmt_misc            20480  1





linux-kernel memory kernel-modules







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    up vote
    1
    down vote

    favorite












    I thought the code for kernel modules was stored in a vmalloc() allocation? (In fact I'm sure the kernel code is using vmalloc(), not kvmalloc()). So why does /proc/meminfo say I have no zero VmallocUsed ?



    $ grep Vmalloc /proc/meminfo
    
VmallocTotal:   34359738367 kB
    
VmallocUsed:           0 kB
    
VmallocChunk:          0 kB
    
$ lsmod|head
    
Module                  Size  Used by
    
vfio_mdev              16384  0
    
mdev                   20480  1 vfio_mdev
    
vfio_iommu_type1       28672  0
    
vfio                   32768  2 vfio_mdev,vfio_iommu_type1
    
kvm_intel             237568  0
    
kvm                   737280  1 kvm_intel
    
irqbypass              16384  1 kvm
    
dummy                  16384  0
    
binfmt_misc            20480  1





    linux-kernel memory kernel-modules







    share|improve this question
























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I thought the code for kernel modules was stored in a vmalloc() allocation? (In fact I'm sure the kernel code is using vmalloc(), not kvmalloc()). So why does /proc/meminfo say I have no zero VmallocUsed ?



      $ grep Vmalloc /proc/meminfo
      
VmallocTotal:   34359738367 kB
      
VmallocUsed:           0 kB
      
VmallocChunk:          0 kB
      
$ lsmod|head
      
Module                  Size  Used by
      
vfio_mdev              16384  0
      
mdev                   20480  1 vfio_mdev
      
vfio_iommu_type1       28672  0
      
vfio                   32768  2 vfio_mdev,vfio_iommu_type1
      
kvm_intel             237568  0
      
kvm                   737280  1 kvm_intel
      
irqbypass              16384  1 kvm
      
dummy                  16384  0
      
binfmt_misc            20480  1





      linux-kernel memory kernel-modules







      share|improve this question













      I thought the code for kernel modules was stored in a vmalloc() allocation? (In fact I'm sure the kernel code is using vmalloc(), not kvmalloc()). So why does /proc/meminfo say I have no zero VmallocUsed ?



      $ grep Vmalloc /proc/meminfo
      
VmallocTotal:   34359738367 kB
      
VmallocUsed:           0 kB
      
VmallocChunk:          0 kB
      
$ lsmod|head
      
Module                  Size  Used by
      
vfio_mdev              16384  0
      
mdev                   20480  1 vfio_mdev
      
vfio_iommu_type1       28672  0
      
vfio                   32768  2 vfio_mdev,vfio_iommu_type1
      
kvm_intel             237568  0
      
kvm                   737280  1 kvm_intel
      
irqbypass              16384  1 kvm
      
dummy                  16384  0
      
binfmt_misc            20480  1





      linux-kernel memory kernel-modules




      linux-kernel memory kernel-modules






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      asked 2 days ago









      sourcejedi

      21.9k43396




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          The fields were zeroed in Linux 4.4, for performance reasons. Programs linked against glibc read this file when they started up, and it was causing a measurable impact.



          https://github.com/torvalds/linux/commit/a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0






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            up vote
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            down vote













            The fields were zeroed in Linux 4.4, for performance reasons. Programs linked against glibc read this file when they started up, and it was causing a measurable impact.



            https://github.com/torvalds/linux/commit/a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0






            share|improve this answer

























              up vote
              2
              down vote













              The fields were zeroed in Linux 4.4, for performance reasons. Programs linked against glibc read this file when they started up, and it was causing a measurable impact.



              https://github.com/torvalds/linux/commit/a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0






              share|improve this answer























                up vote
                2
                down vote










                up vote
                2
                down vote









                The fields were zeroed in Linux 4.4, for performance reasons. Programs linked against glibc read this file when they started up, and it was causing a measurable impact.



                https://github.com/torvalds/linux/commit/a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0






                share|improve this answer












                The fields were zeroed in Linux 4.4, for performance reasons. Programs linked against glibc read this file when they started up, and it was causing a measurable impact.



                https://github.com/torvalds/linux/commit/a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0







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                share|improve this answer



                share|improve this answer










                answered 2 days ago









                sourcejedi

                21.9k43396




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