Balbir Singh wrote:
> Pavel Emelianov wrote:
>>> +static inline bool res_counter_check_under_limit(struct res_counter *cnt)
>>> +{
>>> + bool ret;
>>> + unsigned long flags;
>>> +
>>> + spin_lock_irqsave(&cnt->lock, flags);
>>> + ret = res_counter_limit_check_locked(cnt);
>> We don't have to take the lock for such a check.
>>
>
> This check without the lock could be racy and return incorrect
> results -- leading to OOM.
Maybe. Nevertheless, if we do not trust the return value of
try_to_free_pages() then the code should probably look like
while (1) {
if (res_counter_charge() == 0)
break;
did_progress = try_to_free_pages();
if (res_counter_charge() == 0)
break;
if (!did_progress)
out_of_memory();
}
But in any case we must know for sure was at least one page
freed or not...
Thanks,
Pavel
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