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| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2017-07-10 15:49:29 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-10 16:32:32 -0700 |
| commit | f07e0f849a921ec8c0b509c8b8030455a2b21f7f (patch) | |
| tree | 5b3a6a4174700b917bdfe5f31eac21ec4f9f9909 /mm/interval_tree.c | |
| parent | mm/page_alloc.c: eliminate unsigned confusion in __rmqueue_fallback (diff) | |
| download | linux-dev-f07e0f849a921ec8c0b509c8b8030455a2b21f7f.tar.xz linux-dev-f07e0f849a921ec8c0b509c8b8030455a2b21f7f.zip | |
mm/swap_slots.c: don't disable preemption while taking the per-CPU cache
get_cpu_var() disables preemption and returns the per-CPU version of the
variable. Disabling preemption is useful to ensure atomic access to the
variable within the critical section.
In this case however, after the per-CPU version of the variable is
obtained the ->free_lock is acquired. For that reason it seems the raw
accessor could be used. It only seems that ->slots_ret should be
retested (because with disabled preemption this variable can not be set
to NULL otherwise).
This popped up during PREEMPT-RT testing because it tries to take
spinlocks in a preempt disabled section. In RT, spinlocks can sleep.
Link: http://lkml.kernel.org/r/20170623114755.2ebxdysacvgxzott@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/interval_tree.c')
0 files changed, 0 insertions, 0 deletions