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9852a72123
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Michal Hocko 9852a72123 mm: drop hotplug lock from lru_add_drain_all() 
Pulling cpu hotplug locks inside the mm core function like
lru_add_drain_all just asks for problems and the recent lockdep splat
[1] just proves this.  While the usage in that particular case might be
wrong we should avoid the locking as lru_add_drain_all() is used in many
places.  It seems that this is not all that hard to achieve actually.

We have done the same thing for drain_all_pages which is analogous by
commit a459eeb7b8 ("mm, page_alloc: do not depend on cpu hotplug locks
inside the allocator").  All we have to care about is to handle

      - the work item might be executed on a different cpu in worker from
        unbound pool so it doesn't run on pinned on the cpu

      - we have to make sure that we do not race with page_alloc_cpu_dead
        calling lru_add_drain_cpu

the first part is already handled because the worker calls lru_add_drain
which disables preemption when calling lru_add_drain_cpu on the local
cpu it is draining.  The later is true because page_alloc_cpu_dead is
called on the controlling CPU after the hotplugged CPU vanished
completely.

[1] http://lkml.kernel.org/r/089e0825eec8955c1f055c83d476@google.com

[add a cpu hotplug locking interaction as per tglx]
Link: http://lkml.kernel.org/r/20171116120535.23765-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-31 17:18:36 -08:00
..
acpi Merge branches 'acpi-gpio', 'acpi-button', 'acpi-battery' and 'acpi-video' 2018-01-18 03:02:16 +01:00
asm-generic dma mapping changes for Linux 4.16: 2018-01-31 11:32:27 -08:00
clocksource arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
crypto Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
drm Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
dt-bindings fixes/cleanups for rc1, non-desktop flags for VR 2017-11-23 21:04:56 -10:00
keys
kvm KVM: arm/arm64: timer: Don't set irq as forwarded if no usable GIC 2017-12-18 10:53:23 +01:00
linux mm: drop hotplug lock from lru_add_drain_all() 2018-01-31 17:18:36 -08:00
math-emu
media media: annotate ->poll() instances 2017-11-27 16:20:06 -05:00
memory
misc the rest of drivers/*: annotate ->poll() instances 2017-11-28 11:06:58 -05:00
net Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
pcmcia
ras
rdma RDMA/restrack: Add general infrastructure to track RDMA resources 2018-01-29 20:21:39 -07:00
scsi First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
soc We have two changes to the core framework this time around. The first being a 2017-11-17 20:04:24 -08:00
sound Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2017-11-24 19:19:20 -10:00
trace f2fs-for-4.16-rc1 2018-01-30 19:07:32 -08:00
uapi First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
video fbdev changes for v4.15: 2017-11-20 21:50:24 -10:00
xen xen: fixes for 4.15-rc5 2017-12-22 12:30:10 -08:00