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    SubjectRe: [PATCH] irq: optimize init_kstat_irqs/init_copy_kstat_irqs
    On Mon, 9 Feb 2009 09:37:39 +0100 Ingo Molnar <mingo@elte.hu> wrote:

    >
    > * Andrew Morton <akpm@linux-foundation.org> wrote:
    >
    > > On Mon, 9 Feb 2009 09:11:24 +0100 Ingo Molnar <mingo@elte.hu> wrote:
    > >
    > > >
    > > > * Andrew Morton <akpm@linux-foundation.org> wrote:
    > > >
    > > > > On Sat, 7 Feb 2009 01:01:03 -0800 Yinghai Lu <yinghai@kernel.org> wrote:
    > > > >
    > > > > >
    > > > > > add kzalloc_node_safe()?
    > > > >
    > > > > I cannot find that function.
    > > >
    > > > His suggestion is to provide that allocator variant.
    > > >
    > >
    > > Oh.
    > >
    > > It isn't possible to write a kzalloc_node_safe(GFP_ATOMIC). Or at
    > > least, we've never worked out a way.
    > >
    > > Maybe I'm confused again.
    >
    > Indeed - duh - more morning tea needed.
    >
    > Yinghai, why are those allocations GFP_ATOMIC to begin with? These:
    >
    > earth4:~/tip> grep GFP_ATOMIC kernel/irq/*.c
    > kernel/irq/handle.c: ptr = kzalloc_node(nr * sizeof(*desc->kstat_irqs), GFP_ATOMIC, node);
    > kernel/irq/handle.c: desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
    > kernel/irq/manage.c: action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
    >
    > Should all be GFP_KERNEL. Wherever they are within a spinlocked section the code
    > should be restructured. All descriptor data structures should be preallocated at
    > __setup_irq() time. If we ever need to allocate dynamically later on, in the middle
    > of some difficult codepath that's a structure bug in the code.

    yup, something along those lines.

    > and this one:
    >
    > kernel/irq/numa_migrate.c: desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
    >
    > should fail the migration silently if GFP_ATOMIC returns NULL.

    Silent failure sounds bad?

    The allocation attempt will spew a page-allocation-failure backtrace
    anyway, so people will still get alarmed.

    You might instead choose to suppress that warning with __GFP_NOWARN and
    instead add a more meaningful warning at the calling codesite.




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