linux_dsm_epyc7002/drivers/infiniband/core
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
..
addr.c RDMA/core: Constify dst_addr argument 2018-07-30 20:49:04 -06:00
agent.c
agent.h
cache.c RDMA/core: Remove set-but-not-used variables 2018-07-09 12:11:22 -06:00
cgroup.c
cm_msgs.h IB/cm: Remove unused and erroneous msg sequence encoding 2018-07-09 11:39:28 -06:00
cm.c IB/core: Introduce and use sgid_attr in CM requests 2018-07-26 09:47:47 -06:00
cma_configfs.c
cma_priv.h
cma.c RDMA/core: Prefix _ib to IB/RoCE specific functions 2018-07-30 20:49:04 -06:00
core_priv.h IB/core: Change filter function return type from int to bool 2018-08-15 13:33:20 -06:00
cq.c
device.c RDMA/core: Remove {create,destroy}_ah from mandatory verbs 2018-07-30 20:31:09 -06:00
fmr_pool.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
iwcm.c
iwcm.h
iwpm_msg.c
iwpm_util.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
iwpm_util.h
mad_priv.h IB/mad: Use IDR for agent IDs 2018-06-18 11:22:54 -06:00
mad_rmpp.c
mad_rmpp.h
mad.c RDMA/core: Simplify ib_post_(send|recv|srq_recv)() calls 2018-07-24 16:06:36 -06:00
Makefile IB/uverbs: Remove struct uverbs_root_spec and all supporting code 2018-08-13 09:17:19 -06:00
mr_pool.c
multicast.c IB: Make ib_init_ah_from_mcmember set sgid_attr 2018-06-25 14:19:56 -06:00
netlink.c
nldev.c RDMA/nldev: Return port capability flag for IB only 2018-06-18 11:09:05 -06:00
opa_smi.h
packer.c
rdma_core.c Merge branch 'linus/master' into rdma.git for-next 2018-08-16 14:21:29 -06:00
rdma_core.h IB/uverbs: Remove struct uverbs_root_spec and all supporting code 2018-08-13 09:17:19 -06:00
restrack.c
roce_gid_mgmt.c IB/core: Change filter function return type from int to bool 2018-08-15 13:33:20 -06:00
rw.c RDMA/core: Simplify ib_post_(send|recv|srq_recv)() calls 2018-07-24 16:06:36 -06:00
sa_query.c RDMA: Validate grh_required when handling AVs 2018-07-10 11:13:04 -06:00
sa.h
security.c
smi.c
smi.h
sysfs.c IB/core: Replace ib_query_gid with rdma_get_gid_attr 2018-06-18 11:09:05 -06:00
ucm.c IB/ucm: Fix compiling ucm.c 2018-08-13 20:04:37 -06:00
ucma.c
ud_header.c
umem_odp.c mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
umem.c RDMA/umem: Refactor exit paths in ib_umem_get 2018-07-13 12:15:05 -06:00
user_mad.c IB: Make ib_init_ah_attr_from_wc set sgid_attr 2018-06-25 14:19:56 -06:00
uverbs_cmd.c Linux 4.18 2018-08-16 13:12:00 -06:00
uverbs_ioctl.c IB/uverbs: Do not check for device disassociation during ioctl 2018-08-13 09:17:19 -06:00
uverbs_main.c IB/uverbs: Remove struct uverbs_root_spec and all supporting code 2018-08-13 09:17:19 -06:00
uverbs_marshall.c IB/cm: Replace members of sa_path_rec with 'struct sgid_attr *' 2018-06-25 14:19:57 -06:00
uverbs_std_types_counters.c IB/uverbs: Use uverbs_alloc for allocations 2018-08-13 09:16:13 -06:00
uverbs_std_types_cq.c IB/uverbs: Do not pass struct ib_device to the ioctl methods 2018-08-01 14:55:48 -06:00
uverbs_std_types_dm.c IB/uverbs: Do not pass struct ib_device to the ioctl methods 2018-08-01 14:55:48 -06:00
uverbs_std_types_flow_action.c IB/uverbs: Do not pass struct ib_device to the ioctl methods 2018-08-01 14:55:48 -06:00
uverbs_std_types_mr.c IB/uverbs: Do not pass struct ib_device to the ioctl methods 2018-08-01 14:55:48 -06:00
uverbs_std_types.c IB/uverbs: Remove the ib_uverbs_attr pointer from each attr 2018-08-10 16:06:24 -06:00
uverbs_uapi.c IB/uverbs: Use uverbs_api to unmarshal ioctl commands 2018-08-13 09:17:16 -06:00
uverbs.h IB/uverbs: Remove struct uverbs_root_spec and all supporting code 2018-08-13 09:17:19 -06:00
verbs.c Linux 4.18 2018-08-16 13:12:00 -06:00