Re: [RFC] /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_overcommit_hugepages

[Let's CC Andrew to pick up the patch - please see bellow]

On Tue 04-01-11 23:52:42, CAI Qian wrote:

----- Original Message -----

quoted

On Tue 04-01-11 05:21:46, CAI Qian wrote:

quoted

quoted

quoted

3) overcommit 2gb hugepages.
mmap(NULL, 18446744071562067968, PROT_READ|PROT_WRITE,
MAP_SHARED,
3, 0) = -1 ENOMEM (Cannot allocate memory)

Hmm, you are trying to reserve/mmap a lot of memory (17179869182
1GB
huge pages).

That is strange - the test code merely did this,
addr = mmap(ADDR, 2<<30, PROTECTION, FLAGS, fd, 0);

Didn't you want 1<<30 instead?

No, it was expecting to use both the allocate + overcommited 1GB pages.

Then you propably wanted 2*1UL<<30 rather than 2<<30 which is something
different than you want, I guess. Anyway this is not related to the
bogus value in nr_overcommit_hugepages after your testcase.