Commit e703b7e2 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

futex: Move futex cleanup to __mmdrop() 



Futex hash allocations are done in mm_init() and the cleanup happens in
__mmput(). That works most of the time, but there are mm instances which
are instantiated via mm_alloc() and freed via mmdrop(), which causes the
futex hash to be leaked.

Move the cleanup to __mmdrop().

Fixes: 56180dd2 ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t")
Reported-by: default avatarAndré Draszik <andre.draszik@linaro.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarAndré Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/all/87ldo5ihu0.ffs@tglx
Closes: https://lore.kernel.org/all/0c8cc83bb73abf080faf584f319008b67d0931db.camel@linaro.org
parent 98e8f2c0

kernel/fork.c

+1 −1
Original line number Diff line number Diff line
@@ -686,6 +686,7 @@ void __mmdrop(struct mm_struct *mm) 
	mm_pasid_drop(mm);

	mm_destroy_cid(mm);

	percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS);

	futex_hash_free(mm);



	free_mm(mm);

}
@@ -1133,7 +1134,6 @@ static inline void __mmput(struct mm_struct *mm) 
	if (mm->binfmt)

		module_put(mm->binfmt->module);

	lru_gen_del_mm(mm);

	futex_hash_free(mm);

	mmdrop(mm);

}