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Joonas Lahtinen 73cc0b9aa9 drm/i915: Do not sync RCU during shrinking
Due to the complex dependencies between workqueues and RCU, which
are not easily detected by lockdep, do not synchronize RCU during
shrinking.

On low-on-memory systems (mem=1G for example), the RCU sync leads
to all system workqueus freezing and unrelated lockdep splats are
displayed according to reports. GIT bisecting done by J. R.
Okajima points to the commit where RCU syncing was extended.

RCU sync gains us very little benefit in real life scenarios
where the amount of memory used by object backing storage is
dominant over the metadata under RCU, so drop it altogether.

 " Yeeeaah, if core could just, go ahead and reclaim RCU
   queues, that'd be great. "

  - Chris Wilson, 2016 (0eafec6d32)

v2: More information to commit message.
v3: Remove "grep _rcu_" escapee from i915_gem_shrink_all (Andrea)

Fixes: c053b5a506 ("drm/i915: Don't call synchronize_rcu_expedited under struct_mutex")
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Hugh Dickins <hughd@google.com>
Tested-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: <stable@vger.kernel.org> # v4.11+
Link: http://patchwork.freedesktop.org/patch/msgid/1494414040-11160-1-git-send-email-joonas.lahtinen@linux.intel.com
2017-05-11 15:58:23 +03:00
arch Linux 4.11-rc7 2017-04-19 11:07:14 +10:00
block
certs
crypto
Documentation
drivers drm/i915: Do not sync RCU during shrinking 2017-05-11 15:58:23 +03:00
firmware
fs orangefs: free superblock when mount fails 2017-04-15 09:39:31 -07:00
include main drm pull request for 4.12 kernel 2017-05-03 21:41:35 +02:00
init
ipc
kernel Linux 4.11-rc7 2017-04-19 11:07:14 +10:00
lib
mm zsmalloc: expand class bit 2017-04-13 18:24:21 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2017-04-14 10:47:13 -04:00
samples
scripts
security
sound ALSA: x86: Register multiple PCM devices for the LPE audio card 2017-05-03 16:24:00 +03:00
tools Linux 4.11-rc7 2017-04-19 11:07:14 +10:00
usr
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.cocciconfig
.get_maintainer.ignore
.gitattributes
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.mailmap mailmap: add Martin Kepplinger's email 2017-04-13 18:24:21 -07:00
COPYING
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MAINTAINERS Merge tag 'drm-misc-next-fixes-2017-04-20' of git://anongit.freedesktop.org/git/drm-misc into drm-next 2017-04-21 13:51:59 +10:00
Makefile Linux 4.11-rc7 2017-04-16 13:00:18 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.