mm: handle lru_add_drain_all for UP properly
authorMichal Hocko <mhocko@suse.com>
Thu, 21 Feb 2019 06:19:54 +0000 (22:19 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 21 Feb 2019 17:01:00 +0000 (09:01 -0800)
commit6ea183d60c469560e7b08a83c9804299e84ec9eb
treedf0df79b3330c9b0e556e075ec5b1a250e9b5fab
parent94b3334cbebea34d56a7e6321c6fe9d89b309a49
mm: handle lru_add_drain_all for UP properly

Since for_each_cpu(cpu, mask) added by commit 2d3854a37e8b767a
("cpumask: introduce new API, without changing anything") did not
evaluate the mask argument if NR_CPUS == 1 due to CONFIG_SMP=n,
lru_add_drain_all() is hitting WARN_ON() at __flush_work() added by
commit 4d43d395fed12463 ("workqueue: Try to catch flush_work() without
INIT_WORK().") by unconditionally calling flush_work() [1].

Workaround this issue by using CONFIG_SMP=n specific lru_add_drain_all
implementation.  There is no real need to defer the implementation to
the workqueue as the draining is going to happen on the local cpu.  So
alias lru_add_drain_all to lru_add_drain which does all the necessary
work.

[akpm@linux-foundation.org: fix various build warnings]
[1] https://lkml.kernel.org/r/18a30387-6aa5-6123-e67c-57579ecc3f38@roeck-us.net
Link: http://lkml.kernel.org/r/20190213124334.GH4525@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Debugged-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/swap.c