Red Hat Bugzilla – Bug 191531
kernel dm snapshot: ENOMEM after a number of snapshots
Last modified: 2013-02-28 23:04:19 EST
Description of problem:
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create a pv, vg and finaly an lv, let's call it "test". then
2. for x in $(seq 1 20); do
lvcreate -s -L1G -n test$x /dev/vg/test || break
On my local system I get an ENOMEM after about 16 snapshots.
Many more snapsots, not limited by the maximum size of a single kmalloc.
We have managed to trace the problem to the use of mempools for the _io_pool and
that adding snspshots requires the pool be grown, which ends up hitting the
limits that kmalloc() imposes on allocations.
Is this a known limitiation? Are there any plans to solve/eliminate it? If
somebody were to take on reworking that area of code/design, do you have any
preferences or designs in how it is done?
*** This bug has been marked as a duplicate of 208172 ***