Re: mlock() confusing 1 half of system RAM limit

[Alex Richman]

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@xxxxxxxxxxxx
Engineering
GB Labs
2 Orpheus House,
Calleva park,
Reading
RG7 8TA
Tel:+44 (0)118 455 5000
www.gblabs.com



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