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Message-ID: <20081216173059.GD11683@elte.hu>
Date: Tue, 16 Dec 2008 18:30:59 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Markus Metzger <markus.t.metzger@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, hpa@...or.com,
markus.t.metzger@...il.com, roland@...hat.com,
eranian@...glemail.com
Subject: Re: [rfc] x86, ptrace: memory accounting for branch tracing
* Markus Metzger <markus.t.metzger@...el.com> wrote:
> Account memory allocated for the BTS buffer to the traced task's
> total_vm and locked_vm.
Andrew, is this the right (and preferred) way to attach BTS buffer
allocation overhead to the RLIMIT_MEMLOCK bucket:
> +static int ptrace_bts_allocate_buffer(struct task_struct *child, size_t size)
> +{
> + unsigned long rlim, vm, pgsz;
> + int error = -ENOMEM;
> +
> + pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
> +
> + down_write(&child->mm->mmap_sem);
> +
> + rlim = child->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
> + vm = child->mm->total_vm + pgsz;
> + if (rlim < vm)
> + goto out;
> +
> + rlim = child->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
> + vm = child->mm->locked_vm + pgsz;
> + if (rlim < vm)
> + goto out;
> +
> + child->bts_buffer = kzalloc(size, GFP_KERNEL);
> + if (!child->bts_buffer)
> + goto out;
> +
> + child->bts_size = size;
> +
> + child->mm->total_vm += pgsz;
> + child->mm->locked_vm += pgsz;
> +
> + error = 0;
> + out:
> + up_write(&child->mm->mmap_sem);
> + return error;
?
Ingo
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