Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
register_cpu_notifier(&foobar_cpu_notifier);
put_online_cpus();
This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).
Instead, the correct and race-free way of performing the callback
registration is:
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
init_cpu(cpu);
/* Note the use of the double underscored version of the API */
__register_cpu_notifier(&foobar_cpu_notifier);
cpu_notifier_register_done();
Fix the zswap code by using this latter form of callback registration.
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-mm@kvack.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Git-commit: 576378249c8e0a020aafeaa702c834dff81dd596
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>
zswap is a thin backend for frontswap that takes pages that are in the
process of being swapped out and attempts to compress them and store
them in a RAM-based memory pool. This can result in a significant I/O
reduction on the swap device and, in the case where decompressing from
RAM is faster than reading from the swap device, can also improve
workload performance.
It also has support for evicting swap pages that are currently
compressed in zswap to the swap device on an LRU(ish) basis. This
functionality makes zswap a true cache in that, once the cache is full,
the oldest pages can be moved out of zswap to the swap device so newer
pages can be compressed and stored in zswap.
This patch adds the zswap driver to mm/
Change-Id: I448d18c19f6c61c2ddeb9b764c44a7730e6015e0
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Jenifer Hopper <jhopper@us.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 2b2811178e85553405b86e3fe78357b9b95889ce
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[venkatg@codeaurora.org: keep msm-3.10 changes, add zswap cfg]
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
LuK1337
Srivatsa S. Bhat
Seth Jennings