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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: 56180dd20c ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t")
Reported-by: André Draszik <andre.draszik@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/all/87ldo5ihu0.ffs@tglx
Closes: https://lore.kernel.org/all/0c8cc83bb73abf080faf584f319008b67d0931db.camel@linaro.org
This commit is contained in:
Thomas Gleixner 2025-07-30 21:44:55 +02:00
parent 98e8f2c0e0
commit e703b7e247
1 changed files with 1 additions and 1 deletions
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kernel/fork.c
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@ -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);
}