Le samedi 30 octobre 2010 Ã 00:28 +0400, Cyrill Gorcunov a Ãcrit :
> On Fri, Oct 29, 2010 at 08:32:26PM +0200, Peter Zijlstra wrote:
> > On Fri, 2010-10-29 at 06:43 +0000, tip-bot for Eric Dumazet wrote:
> > > + irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
> > > + THREAD_FLAGS,
> > > + THREAD_ORDER));
> >
> > Shouldn't we be checking for a NULL return from alloc_pages_node()
> > before calling page_address() on it?
> > --
>
I didnt check for NULL because original code was not either.
If you cannot allocate memory for the IRQ stack, only choice is to crash
anyway.
Adding BUG_ON() is not that helpful in this respect.
> Something like below I guess, but probably we could try to allocate
> on appropriate NUMA node first and if it fails -- via old alloc_pages
> and if it fail in turn -- then we panic.
>
> Cyrill
> ---
> arch/x86/kernel/irq_32.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> Index: linux-2.6.git/arch/x86/kernel/irq_32.c
> =====================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/irq_32.c
> +++ linux-2.6.git/arch/x86/kernel/irq_32.c
> @@ -122,13 +122,16 @@ execute_on_irq_stack(int overflow, struc
> void __cpuinit irq_ctx_init(int cpu)
> {
> union irq_ctx *irqctx;
> + struct page *page;
>
> if (per_cpu(hardirq_ctx, cpu))
> return;
>
> - irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
> - THREAD_FLAGS,
> - THREAD_ORDER));
> + page = alloc_pages_node(cpu_to_node(cpu),
> + THREAD_FLAGS, THREAD_ORDER);
> + BUG_ON(!page);
> +
> + irqctx = page_address(page);
> irqctx->tinfo.task = NULL;
> irqctx->tinfo.exec_domain = NULL;
> irqctx->tinfo.cpu = cpu;
> @@ -137,9 +140,11 @@ void __cpuinit irq_ctx_init(int cpu)
>
> per_cpu(hardirq_ctx, cpu) = irqctx;
>
> - irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
> - THREAD_FLAGS,
> - THREAD_ORDER));
> + page = alloc_pages_node(cpu_to_node(cpu),
> + THREAD_FLAGS, THREAD_ORDER);
> + BUG_ON(!page);
> +
> + irqctx = page_address(page);
> irqctx->tinfo.task = NULL;
> irqctx->tinfo.exec_domain = NULL;
> irqctx->tinfo.cpu = cpu;
--
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