From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux.com>
Cc: akpm@linux-foundation.org, laijs@cn.fujitsu.com,
linux-kernel@vger.kernel.org, vgoyal@redhat.com,
stable@vger.kernel.org
Subject: Re: [PATCH 02/15] percpu: perform tlb flush after pcpu_map_pages() failure
Date: Sat, 23 Aug 2014 13:10:56 -0400 [thread overview]
Message-ID: <20140823171056.GE13540@mtj.dyndns.org> (raw)
In-Reply-To: <alpine.DEB.2.11.1408231039220.29970@gentwo.org>
On Sat, Aug 23, 2014 at 10:40:29AM -0500, Christoph Lameter wrote:
> On Fri, 22 Aug 2014, Tejun Heo wrote:
>
> > If pcpu_map_pages() fails midway, it unmaps the already mapped pages.
> > Currently, it doesn't flush tlb after the partial unmapping. This may
> > be okay in most cases as the established mapping hasn't been used at
> > that point but it can go wrong and when it goes wrong it'd be
> > extremely difficult to track down.
>
> So why is this separate? You added the unmapping in the last patch without
> the flushing and this is a fixup for the patch before?
This was originally separated out so that flushes can be done once per
chunk as some of the flushes involve sending IPIs to all CPUs. After
this patchset, more of alloc/free logic is implemented in the percpu
core so it probably would be better to expose the flush interface too
so that all can be driven from the core.
Thanks.
--
tejun
next prev parent reply other threads:[~2014-08-23 17:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-22 16:53 [PATCHSET REPOST percpu/for-3.18] percpu: implement atomic allocation support Tejun Heo
2014-08-22 16:53 ` [PATCH 01/15] percpu: fix pcpu_alloc_pages() failure path Tejun Heo
2014-08-23 15:38 ` Christoph Lameter
2014-08-22 16:53 ` [PATCH 02/15] percpu: perform tlb flush after pcpu_map_pages() failure Tejun Heo
2014-08-23 15:40 ` Christoph Lameter
2014-08-23 17:10 ` Tejun Heo [this message]
2014-08-22 16:53 ` [PATCH 03/15] percpu: remove the usage of separate populated bitmap in percpu-vm Tejun Heo
2014-08-23 15:57 ` Christoph Lameter
2014-08-22 16:53 ` [PATCH 04/15] percpu: remove @may_alloc from pcpu_get_pages() Tejun Heo
2014-08-22 16:53 ` [PATCH 05/15] percpu: move common parts out of pcpu_[de]populate_chunk() Tejun Heo
2014-08-22 16:53 ` [PATCH 06/15] percpu: move region iterations " Tejun Heo
2014-08-22 16:53 ` [PATCH 07/15] percpu: make percpu-km set chunk->populated bitmap properly Tejun Heo
2014-08-23 16:00 ` Christoph Lameter
2014-08-22 16:53 ` [PATCH 08/15] percpu: restructure locking Tejun Heo
2014-08-22 16:53 ` [PATCH 09/15] percpu: make pcpu_alloc_area() capable of allocating only from populated areas Tejun Heo
2014-08-22 16:53 ` [PATCH 10/15] percpu: indent the population block in pcpu_alloc() Tejun Heo
2014-08-22 16:53 ` [PATCH 11/15] percpu: implement [__]alloc_percpu_gfp() Tejun Heo
2014-08-22 16:53 ` [PATCH 12/15] percpu: make sure chunk->map array has available space Tejun Heo
2014-08-22 16:53 ` [PATCH 13/15] percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated Tejun Heo
2014-08-22 16:53 ` [PATCH 14/15] percpu: rename pcpu_reclaim_work to pcpu_balance_work Tejun Heo
2014-08-22 16:53 ` [PATCH 15/15] percpu: implement asynchronous chunk population Tejun Heo
2014-09-02 18:50 ` [PATCHSET REPOST percpu/for-3.18] percpu: implement atomic allocation support Tejun Heo
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