Re: When booting a 16TB system, unix_create1 fails due to integer overflow.

David Miller
2010-09-27T22:36:21Z

From: Dipankar Sarma <dipankar@in.ibm.com>
Date: Thu, 23 Sep 2010 19:40:37 +0530

> On Thu, Sep 23, 2010 at 02:53:04PM +0200, Eric Dumazet wrote:
>> Le jeudi 23 septembre 2010 à 07:17 -0500, Robin Holt a écrit :
>> > I do not know which direction to take, but here is the summary of the
>> > problem.
>> >
>> > We recently started trying to boot a customer's two new machines which
>> > are configured with 384GB short of 16TB of memory.
>> >
>> > We were seeing a failure which prevented boot. The kernel was incapable
>> > of creating either a named pipe or unix domain socket. This comes down
>> > to a common kernel function called unix_create1() which does:
>> >
>> > atomic_inc(&unix_nr_socks);
>> > if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
>> > goto out;
>> >
>>
>> Hi Robin
>>
>> I would say : We can use atomic_long_t instead of atomic_t
>>
>> And make get_max_files(void) return a long ?
>>
>> Something like :
>>
>>
>> fs/file_table.c | 10 +++++-----
>> include/linux/fs.h | 2 +-
>> net/unix/af_unix.c | 14 +++++++-------
>> 3 files changed, 13 insertions(+), 13 deletions(-)
>>
>> diff --git a/fs/file_table.c b/fs/file_table.c
>>
>> n = (mempages * (PAGE_SIZE / 1024)) / 10;
>> - files_stat.max_files = n;
>> + files_stat.max_files = min(n, 0x7FFFFFFFUL);
>
> It may be cleaner to just convert both the file counters and
> the file limits to usnsigned long.
>
> Other than that, this seems like a reasonable thing to do.

Is someone following up on integrating this upstream so this thing
gets fixed?

Thanks.