mm/page_alloc: explicitly acquire the zone lock in __free_pages_ok

__free_pages_ok() disables IRQs before calling a common helper
free_one_page() that acquires the zone lock.  This is not safe according
to Documentation/locking/locktypes.rst and in this context, IRQ disabling
is not protecting a per_cpu_pages structure either or a local_lock would
be used.

This patch explicitly acquires the lock with spin_lock_irqsave instead of
relying on a helper.  This removes the last instance of local_irq_save()
in page_alloc.c.

Link: https://lkml.kernel.org/r/20210512095458.30632-8-mgorman@techsingularity.net


Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>