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From: Alex Richman <alex.r@gblabs.co.uk>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-man@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: mlock() confusing 1 half of system RAM limit
Date: Fri, 1 Jun 2018 14:24:23 +0100	[thread overview]
Message-ID: <1ae5c450-1ffe-cf15-e878-b40f30c0acc3@gblabs.co.uk> (raw)
In-Reply-To: <20180601130524.GB15278@dhcp22.suse.cz>

Ah, that's it.  Increased the limit on the mount and it works fine now.

Thanks!
- Alex.

On 01/06/18 14:05, Michal Hocko wrote:
> On Fri 01-06-18 13:26:59, Alex Richman wrote:
>> I am using a shm MAP_SHARED, along these lines:
>>> shm_fd = shm_open(handle, (O_RDWR | O_CREAT), (S_IRWXU | S_IRWXG |
>> S_IRWXO));
>>> ftruncate(shm_fd, channel->sled_size)
>>> channel->sled = mmap(NULL, channel->sled_size, (PROT_READ | PROT_WRITE),
>>> (MAP_SHARED | MAP_NORESERVE), shm_fd, 0);
>>> mlock(channel->sled, channel->sled_size) /* Fails with ENOMEM. */
>> But shmmax is unlimited on my box:
>> # sysctl -a | grep shm
>> kernel.shm_next_id = -1
>> kernel.shm_rmid_forced = 0
>> kernel.shmall = 18446744073692774399
>> kernel.shmmax = 18446744073692774399
>> kernel.shmmni = 4096
>>
>> Any ideas?
> shm_open uses tmpfs/shmem under the cover and that has the internal
> limit as explained above.

-- 
Alex Richman
alex.r@gblabs.co.uk
Engineering
GB Labs
2 Orpheus House,
Calleva park,
Reading
RG7 8TA
Tel:+44 (0)118 455 5000
www.gblabs.com



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  reply	other threads:[~2018-06-01 13:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-01  9:53 Alex Richman
2018-06-01 11:44 ` Michal Hocko
2018-06-01 12:26   ` Alex Richman
2018-06-01 13:05     ` Michal Hocko
2018-06-01 13:24       ` Alex Richman [this message]
2018-06-01 13:41         ` Michal Hocko

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