From: Josh Cartwright <joshc@ni.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
Borislav Petkov <bp@alien8.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Brian Gerst <brgerst@gmail.com>, Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v6 1/3] fork: Add generic vmalloced stack support
Date: Tue, 30 Aug 2016 17:26:12 -0500 [thread overview]
Message-ID: <20160830222612.GK26784@jcartwri.amer.corp.natinst.com> (raw)
In-Reply-To: <CALCETrWHEWge=xxDkp7SnU=MgbPYOY8kK3F98ABXAOXNObp50A@mail.gmail.com>
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On Tue, Aug 30, 2016 at 03:01:51PM -0700, Andy Lutomirski wrote:
> On Wed, Aug 24, 2016 at 9:51 AM, Josh Cartwright <joshc@ni.com> wrote:
[..]
> >> diff --git a/kernel/fork.c b/kernel/fork.c
> >> index 52e725d4a866..05f7ef796fb4 100644
> >> --- a/kernel/fork.c
> >> +++ b/kernel/fork.c
> >> @@ -158,19 +158,39 @@ void __weak arch_release_thread_stack(unsigned long *stack)
> >> * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
> >> * kmemcache based allocator.
> >> */
> >> -# if THREAD_SIZE >= PAGE_SIZE
> >> -static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
> >> - int node)
> >> +# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
> >> +static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
> >> {
> >> +#ifdef CONFIG_VMAP_STACK
> >> + void *stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE,
> >> + VMALLOC_START, VMALLOC_END,
> >> + THREADINFO_GFP | __GFP_HIGHMEM,
> >> + PAGE_KERNEL,
> >> + 0, node,
> >> + __builtin_return_address(0));
> >> +
> >> + /*
> >> + * We can't call find_vm_area() in interrupt context, and
> >> + * free_thread_stack can be called in interrupt context, so cache
> >> + * the vm_struct.
> >> + */
> >> + if (stack)
> >> + tsk->stack_vm_area = find_vm_area(stack);
> >
> > This is annoying, we end up having to walk the vm_area tree twice (once
> > for the allocation, then here to get a handle on area).
> >
> > Perhaps it's time the vmalloc code learned an allocation API that
> > returned the vm_area handle as well.
>
> Agreed. I may do this once everything else lands.
There are at least a few other places that could benefit from this,
doing a quick scan of find_vm_area() callers: vmalloc_{32_,}_user() and
kasan_module_alloc().
Josh
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next prev parent reply other threads:[~2016-08-30 22:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 9:35 [PATCH v6 0/3] virtually mapped stacks Andy Lutomirski
2016-08-11 9:35 ` [PATCH v6 1/3] fork: Add generic vmalloced stack support Andy Lutomirski
2016-08-15 11:55 ` Michal Hocko
2016-08-24 10:03 ` Ingo Molnar
2016-08-24 16:11 ` Dmitry Vyukov
2016-08-24 13:02 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-08-24 16:51 ` [PATCH v6 1/3] " Josh Cartwright
2016-08-30 22:01 ` Andy Lutomirski
2016-08-30 22:26 ` Josh Cartwright [this message]
2016-08-11 9:35 ` [PATCH v6 2/3] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Andy Lutomirski
2016-08-24 13:02 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-08-11 9:35 ` [PATCH v6 3/3] x86/mm/64: Enable " Andy Lutomirski
2016-08-24 13:03 ` [tip:x86/asm] x86/mm/64: Enable vmapped stacks (CONFIG_HAVE_ARCH_VMAP_STACK=y) tip-bot for Andy Lutomirski
2016-10-21 12:32 ` Matt Fleming
2016-10-22 0:18 ` Andy Lutomirski
2016-10-24 13:09 ` Matt Fleming
2016-10-30 16:21 ` Andy Lutomirski
2016-11-07 12:32 ` Matt Fleming
2016-08-20 18:06 ` [PATCH v6 0/3] virtually mapped stacks Andy Lutomirski
2016-08-24 10:12 ` Ingo Molnar
2016-08-24 15:27 ` Andy Lutomirski
2016-08-24 17:16 ` Ingo Molnar
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