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From: Joel Fernandes <joelaf@google.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jisheng Zhang <jszhang@marvell.com>,
	John Dias <joaodias@google.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	linux-rt-users@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping
Date: Thu, 20 Oct 2016 17:32:19 -0700	[thread overview]
Message-ID: <CAJWu+oric2eq1WOrx9fKHxiMhyq490av-1TbRPDfTptOydfM+A@mail.gmail.com> (raw)
In-Reply-To: <20161019163112.GA31091@lst.de>

Hi Christoph,

On Wed, Oct 19, 2016 at 9:31 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Wed, Oct 19, 2016 at 08:34:40AM -0700, Andy Lutomirski wrote:
>>
>> It would be quite awkward for a task stack to get freed from a
>> sleepable context, because the obvious sleepable context is the task
>> itself, and it still needs its stack.  This was true even in the old
>> regime when task stacks were freed from RCU context.
>>
>> But vfree has a magic automatic deferral mechanism.  Couldn't you make
>> the non-deferred case might_sleep()?
>
> But it's only magic from interrupt context..
>
> Chris, does this patch make virtually mapped stack work for you again?
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index f2481cb..942e02d 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1533,7 +1533,7 @@ void vfree(const void *addr)
>
>         if (!addr)
>                 return;
> -       if (unlikely(in_interrupt())) {
> +       if (in_interrupt() || in_atomic()) {

in_atomic() also checks in_interrupt() cases so only in_atomic() should suffice.

Thanks,

Joel

  parent reply	other threads:[~2016-10-21  0:32 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-18  6:56 [RFC] reduce latency in __purge_vmap_area_lazy Christoph Hellwig
2016-10-18  6:56 ` [PATCH 1/6] mm: refactor __purge_vmap_area_lazy Christoph Hellwig
2016-10-18  6:56 ` [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping Christoph Hellwig
2016-10-18 10:33   ` Chris Wilson
2016-10-18 10:38     ` Christoph Hellwig
2016-10-19 11:15   ` Chris Wilson
2016-10-19 13:05     ` Christoph Hellwig
2016-10-19 15:34       ` Andy Lutomirski
2016-10-19 16:31         ` Christoph Hellwig
2016-10-19 19:43           ` Chris Wilson
2016-10-21  0:32           ` Joel Fernandes [this message]
2016-11-08 13:24     ` Joel Fernandes
2016-11-08 14:32       ` Andrey Ryabinin
2016-10-18  6:56 ` [PATCH 3/6] mm: remove free_unmap_vmap_area_noflush Christoph Hellwig
2016-10-18  6:56 ` [PATCH 4/6] mm: remove free_unmap_vmap_area_addr Christoph Hellwig
2016-10-21  0:46   ` Joel Fernandes
2016-10-21  1:58     ` Nicholas Piggin
2016-10-18  6:56 ` [PATCH 5/6] mm: turn vmap_purge_lock into a mutex Christoph Hellwig
2016-10-18  6:56 ` [PATCH 6/6] mm: add preempt points into __purge_vmap_area_lazy Christoph Hellwig
2016-10-18 20:56   ` Steven Rostedt
2016-10-18 21:01     ` Steven Rostedt
2016-10-18 10:40 ` [RFC] reduce latency in __purge_vmap_area_lazy Nicholas Piggin
2016-10-18 11:21 ` Jisheng Zhang
2016-10-21  1:08 ` Joel Fernandes

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