From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Joel Fernandes <joelaf@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jisheng Zhang <jszhang@marvell.com>,
"Chris Wilson" <chris@chris-wilson.co.uk>,
John Dias <joaodias@google.com>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
<linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"Andy Lutomirski" <luto@kernel.org>
Subject: Re: [PATCH 4/7] mm: defer vmalloc from atomic context
Date: Tue, 8 Nov 2016 18:03:58 +0300 [thread overview]
Message-ID: <747aa42a-c236-ee25-eef5-59644687f01b@virtuozzo.com> (raw)
In-Reply-To: <20161107150947.GA11279@lst.de>
On 11/07/2016 06:09 PM, Christoph Hellwig wrote:
> On Mon, Nov 07, 2016 at 06:01:45PM +0300, Andrey Ryabinin wrote:
>>> So because in_atomic doesn't work for !CONFIG_PREEMPT kernels, can we
>>> always defer the work in these cases?
>>>
>>> So for non-preemptible kernels, we always defer:
>>>
>>> if (!IS_ENABLED(CONFIG_PREEMPT) || in_atomic()) {
>>> // defer
>>> }
>>>
>>> Is this fine? Or any other ideas?
>>>
>>
>> What's wrong with my idea?
>> We can add vfree_in_atomic() and use it to free vmapped stacks
>> and for any other places where vfree() used 'in_atomict() && !in_interrupt()' context.
>
> I somehow missed the mail, sorry. That beeing said always defer is
> going to suck badly in terms of performance, so I'm not sure it's an all
> that good idea.
>
> vfree_in_atomic sounds good, but I wonder if we'll need to annotate
> more callers than just the stacks. I'm fairly bust this week, do you
> want to give that a spin? Otherwise I'll give it a try towards the
> end of this week or next week.
>
Yeah, it appears that we need more annotations. I've found another case in free_ldt_struct(),
and I bet it won't be the last.
I'll send patches.
next prev parent reply other threads:[~2016-11-08 17:36 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-22 15:17 reduce latency in __purge_vmap_area_lazy Christoph Hellwig
2016-10-22 15:17 ` [PATCH 1/7] mm: remove free_unmap_vmap_area_noflush Christoph Hellwig
2016-10-22 15:17 ` [PATCH 2/7] mm: remove free_unmap_vmap_area_addr Christoph Hellwig
2016-10-22 15:17 ` [PATCH 3/7] mm: refactor __purge_vmap_area_lazy Christoph Hellwig
2016-10-22 15:17 ` [PATCH 4/7] mm: defer vmalloc from atomic context Christoph Hellwig
2016-10-24 15:44 ` Andrey Ryabinin
2016-11-05 3:43 ` Joel Fernandes
2016-11-07 15:01 ` Andrey Ryabinin
2016-11-07 15:09 ` Christoph Hellwig
2016-11-08 15:03 ` Andrey Ryabinin [this message]
2016-11-08 15:05 ` [PATCH 1/3] mm/vmalloc: add vfree_atomic() Andrey Ryabinin
2016-11-08 15:05 ` [PATCH 2/3] kernel/fork: use vfree_atomic() to free thread stack Andrey Ryabinin
2016-11-08 15:05 ` [PATCH 3/3] x86/ldt: use vfree_atomic() to free ldt entries Andrey Ryabinin
2016-11-07 16:50 ` [PATCH 4/7] mm: defer vmalloc from atomic context Joel Fernandes
2016-10-22 15:17 ` [PATCH 5/7] mm: mark all calls into the vmalloc subsystem as potentially sleeping Christoph Hellwig
2016-10-22 15:17 ` [PATCH 6/7] mm: turn vmap_purge_lock into a mutex Christoph Hellwig
2016-10-22 15:17 ` [PATCH 7/7] mm: add preempt points into __purge_vmap_area_lazy Christoph Hellwig
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