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Re: [PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE

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On Thu,  5 Nov 2015 11:50:35 +0000 Catalin Marinas <catalin.marinas@arm.com> wrote:

> Commit 8fc9cf420b36 ("slab: make more slab management structure off the
> slab") enables off-slab management objects for sizes starting with
> PAGE_SIZE >> 5. This means 128 bytes for a 4KB page configuration.
> However, on systems with a KMALLOC_MIN_SIZE of 128 (arm64 in 4.4), such
> optimisation does not make sense since the slab management allocation
> would take 128 bytes anyway (even though freelist_size is 32) with the
> additional overhead of another allocation.
> 
> This patch introduces an OFF_SLAB_MIN_SIZE macro which takes
> KMALLOC_MIN_SIZE into account. It also solves a slab bug on arm64 where
> the first kmalloc_cache to be initialised after slab_early_init = 0,
> "kmalloc-128", fails to allocate off-slab management objects from the
> same "kmalloc-128" cache.

That all seems to be quite minor stuff.

> Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab")
> Cc: <stable@vger.kernel.org> # 3.15+

Yet you believe the fix should be backported.

So, the usual refrain: when fixing a bug, please describe the end-user
visible effects of that bug.

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Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-03 13:10 +0100
  Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-03 15:40 +0100
    Re: [PATCH] arm64: Increase the max granular size Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-03 16:00 +0100
      Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-03 20:00 +0100
        Re: [PATCH] arm64: Increase the max granular size Christoph Lameter <cl@linux.com> - 2015-11-04 00:40 +0100
          Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-04 13:40 +0100
            Re: [PATCH] arm64: Increase the max granular size Christoph Lameter <cl@linux.com> - 2015-11-04 15:00 +0100
              Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-04 16:00 +0100
                Re: [PATCH] arm64: Increase the max granular size Christoph Lameter <cl@linux.com> - 2015-11-04 16:30 +0100
                Re: [PATCH] arm64: Increase the max granular size Catalin Marinas <catalin.marinas@arm.com> - 2015-11-04 16:40 +0100
                Re: [PATCH] arm64: Increase the max granular size Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2015-11-05 05:40 +0100
                [PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE Catalin Marinas <catalin.marinas@arm.com> - 2015-11-05 13:00 +0100
                Re: [PATCH] mm: slab: Only move management objects off-slab for  sizes larger than KMALLOC_MIN_SIZE Andrew Morton <akpm@linux-foundation.org> - 2015-11-05 14:30 +0100
                Re: [PATCH] mm: slab: Only move management objects off-slab for  sizes larger than KMALLOC_MIN_SIZE Catalin Marinas <catalin.marinas@arm.com> - 2015-11-05 17:10 +0100
                Re: [PATCH] mm: slab: Only move management objects off-slab for sizes  larger than KMALLOC_MIN_SIZE Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-06 14:10 +0100
                Re: [PATCH] mm: slab: Only move management objects off-slab for  sizes larger than KMALLOC_MIN_SIZE Christoph Lameter <cl@linux.com> - 2015-11-05 18:40 +0100

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