Re: [patch 3/9] no PF_MEMALLOC tinkering

[Andrew Morton]

Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
>
> PF_MEMALLOC is really not a tool for tinkering. It is pretty specifically
>  used to prevent recursion into page reclaim, and to prevent low memory
>  deadlocks.
> 
>  The mm/swap_state.c code was the only legitimate tinkerer. Its concern
>  was addressed by the previous patch.

What previous patch?  radix tree allocation doesn't use mempools, so this
patch will cause add_to_swap() to oom the machine with radix tree node
allocations.

Now if we were to add __GFP_NOMEMALLOC in add_to_swap() then things would
work as we want them to.


The dm_crypt change looks OK.


The code in mpage.c is saying "if we failed to allocate a correctly-sized
bvec and if we're doing pageout then try to allocate a smaller-sized bvec
instead".

It's probably fairly useless, but afaict there's nothing in any of the
other patches here which makes it redundant.


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