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Re: [PATCH] mm: introduce kv[mz]alloc helpers

From Joe Perches <joe@perches.com>
Newsgroups linux.kernel
Subject Re: [PATCH] mm: introduce kv[mz]alloc helpers
Date 2017-01-02 17:00 +0100
Message-ID <sVdbH-uc-3@gated-at.bofh.it> (permalink)
References <sVb0e-7pH-41@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, 2017-01-02 at 14:37 +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> Using kmalloc with the vmalloc fallback for larger allocations is a
> common pattern in the kernel code. Yet we do not have any common helper
> for that and so users have invented their own helpers. Some of them are
> really creative when doing so. Let's just add kv[mz]alloc and make sure
> it is implemented properly. This implementation makes sure to not make
> a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also
> to not warn about allocation failures. This also rules out the OOM
> killer as the vmalloc is a more approapriate fallback than a disruptive
> user visible action.
> 
> This patch also changes some existing users and removes helpers which
> are specific for them. In some cases this is not possible (e.g.
> ext4_kvmalloc, libcfs_kvzalloc, __aa_kvmalloc) because those seems to be
> broken and require GFP_NO{FS,IO} context which is not vmalloc compatible
> in general (note that the page table allocation is GFP_KERNEL). Those
> need to be fixed separately.
> 
> apparmor has already claimed kv[mz]alloc so remove those and use
> __aa_kvmalloc instead to prevent from the naming clashes.

I have no real objection but perhaps this would
be better done as 3 or more patches

o rename apparmor uses
o introduce generic
o conversions to generic

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Thread

[PATCH] mm: introduce kv[mz]alloc helpers Michal Hocko <mhocko@kernel.org> - 2017-01-02 14:40 +0100
  Re: [PATCH] mm: introduce kv[mz]alloc helpers Joe Perches <joe@perches.com> - 2017-01-02 17:00 +0100
    Re: [PATCH] mm: introduce kv[mz]alloc helpers Michal Hocko <mhocko@kernel.org> - 2017-01-02 17:10 +0100
  Re: [PATCH] mm: introduce kv[mz]alloc helpers Vlastimil Babka <vbabka@suse.cz> - 2017-01-03 11:30 +0100
    Re: [PATCH] mm: introduce kv[mz]alloc helpers Michal Hocko <mhocko@kernel.org> - 2017-01-03 11:40 +0100

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