linux_dsm_epyc7002/include/rdma
Michal Hocko 93065ac753 mm, oom: distinguish blockable mode for mmu notifiers
There are several blockable mmu notifiers which might sleep in
mmu_notifier_invalidate_range_start and that is a problem for the
oom_reaper because it needs to guarantee a forward progress so it cannot
depend on any sleepable locks.

Currently we simply back off and mark an oom victim with blockable mmu
notifiers as done after a short sleep.  That can result in selecting a new
oom victim prematurely because the previous one still hasn't torn its
memory down yet.

We can do much better though.  Even if mmu notifiers use sleepable locks
there is no reason to automatically assume those locks are held.  Moreover
majority of notifiers only care about a portion of the address space and
there is absolutely zero reason to fail when we are unmapping an unrelated
range.  Many notifiers do really block and wait for HW which is harder to
handle and we have to bail out though.

This patch handles the low hanging fruit.
__mmu_notifier_invalidate_range_start gets a blockable flag and callbacks
are not allowed to sleep if the flag is set to false.  This is achieved by
using trylock instead of the sleepable lock for most callbacks and
continue as long as we do not block down the call chain.

I think we can improve that even further because there is a common pattern
to do a range lookup first and then do something about that.  The first
part can be done without a sleeping lock in most cases AFAICS.

The oom_reaper end then simply retries if there is at least one notifier
which couldn't make any progress in !blockable mode.  A retry loop is
already implemented to wait for the mmap_sem and this is basically the
same thing.

The simplest way for driver developers to test this code path is to wrap
userspace code which uses these notifiers into a memcg and set the hard
limit to hit the oom.  This can be done e.g.  after the test faults in all
the mmu notifier managed memory and set the hard limit to something really
small.  Then we are looking for a proper process tear down.

[akpm@linux-foundation.org: coding style fixes]
[akpm@linux-foundation.org: minor code simplification]
Link: http://lkml.kernel.org/r/20180716115058.5559-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christian König <christian.koenig@amd.com> # AMD notifiers
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx and umem_odp
Reported-by: David Rientjes <rientjes@google.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Sudeep Dutt <sudeep.dutt@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:44 -07:00
..
ib_addr.h RDMA/core: Constify dst_addr argument 2018-07-30 20:49:04 -06:00
ib_cache.h Revert "net/smc: Replace ib_query_gid with rdma_get_gid_attr" 2018-08-16 14:03:34 -06:00
ib_cm.h RDMA/cma: Constify path record, ib_cm_event, listen_id pointers 2018-07-30 20:49:04 -06:00
ib_fmr_pool.h
ib_hdrs.h IB/hfi1: Remove unnecessary fecn and becn fields 2018-02-01 15:43:29 -07:00
ib_mad.h RDMA: Fix storage of PortInfo CapabilityMask in the kernel 2018-07-10 11:06:45 -06:00
ib_marshall.h IB/core: Convert ah_attr from OPA to IB when copying to user 2017-08-08 14:47:18 -04:00
ib_pack.h IB/core: Fix calculation of maximum RoCE MTU 2017-10-18 12:11:36 -04:00
ib_pma.h
ib_sa.h IB/cm: Replace members of sa_path_rec with 'struct sgid_attr *' 2018-06-25 14:19:57 -06:00
ib_smi.h
ib_umem_odp.h mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
ib_umem.h IB/umem: Use the correct mm during ib_umem_release 2018-05-15 17:09:10 -06:00
ib_verbs.h Linux 4.18 2018-08-16 13:12:00 -06:00
ib.h RDMA/core: Return bool instead of int 2018-07-30 20:49:04 -06:00
iw_cm.h
iw_portmap.h
mr_pool.h
opa_addr.h include/rdma/opa_addr.h: Fix an endianness issue 2018-07-03 14:11:34 -06:00
opa_port_info.h IB/hfi1: Virtual Network Interface Controller (VNIC) HW support 2017-04-20 15:19:35 -04:00
opa_smi.h
opa_vnic.h IB/hfi1: Add support to receive 16B bypass packets 2017-08-22 14:22:37 -04:00
rdma_cm_ib.h RDMA/{cma, ucma}: Simplify and rename rdma_set_ib_paths 2018-01-10 22:00:33 -07:00
rdma_cm.h RDMA/core: Constify dst_addr argument 2018-07-30 20:49:04 -06:00
rdma_netlink.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rdma_vt.h IB/{hfi1, rdmavt, qib}: Implement CQ completion vector support 2018-05-09 15:53:30 -04:00
rdmavt_cq.h IB/{hfi1, rdmavt, qib}: Implement CQ completion vector support 2018-05-09 15:53:30 -04:00
rdmavt_mr.h IB/rdmavt: Handle dereg of inuse MRs properly 2017-08-28 19:12:31 -04:00
rdmavt_qp.h IB/rdmavt, IB/hfi1: Create device dependent s_flags 2018-06-19 11:49:46 -06:00
restrack.h RDMA/restrack: Change SPDX tag to properly reflect license 2018-06-05 14:04:20 -06:00
rw.h rdma core: Add rdma_rw_mr_payload() 2017-09-05 15:15:30 -04:00
uverbs_ioctl.h IB/uverbs: Remove struct uverbs_root_spec and all supporting code 2018-08-13 09:17:19 -06:00
uverbs_named_ioctl.h IB/mlx5: Introduce driver create and destroy flow methods 2018-07-24 14:03:49 -06:00
uverbs_std_types.h IB/uverbs: Use uverbs_api to manage the object type inside the uobject 2018-08-10 16:06:24 -06:00
uverbs_types.h IB/uverbs: Use uverbs_api to manage the object type inside the uobject 2018-08-10 16:06:24 -06:00