memcg: objcg stock trylock without irq disabling

There is no need to disable irqs to use objcg per-cpu stock, so let's just
not do that but consume_obj_stock() and refill_obj_stock() will need to
use trylock instead to avoid deadlock against irq.  One consequence of
this change is that the charge request from irq context may take slowpath
more often but it should be rare.

Link: https://lkml.kernel.org/r/20250514184158.3471331-8-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>