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mm, notifier: Catch sleeping/blocking for !blockable 

We need to make sure implementations don't cheat and don't have a possible
schedule/blocking point deeply burried where review can't catch it.

I'm not sure whether this is the best way to make sure all the
might_sleep() callsites trigger, and it's a bit ugly in the code flow.
But it gets the job done.

Inspired by an i915 patch series which did exactly that, because the rules
haven't been entirely clear to us.

Link: https://lore.kernel.org/r/20190826201425.17547-5-daniel.vetter@ffwll.ch
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Jérôme Glisse <jglisse@redhat.com> (v4)
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Daniel Vetter 2019-08-26 22:14:24 +02:00 committed by Jason Gunthorpe
parent 312364f353
commit ba170f76b6
1 changed files with 13 additions and 2 deletions
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15
mm/mmu_notifier.c
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@ -168,7 +168,13 @@ int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
id = srcu_read_lock(&srcu);
hlist_for_each_entry_rcu(mn, &range->mm->mmu_notifier_mm->list, hlist) {
if (mn->ops->invalidate_range_start) {
int _ret = mn->ops->invalidate_range_start(mn, range);
int _ret;
if (!mmu_notifier_range_blockable(range))
non_block_start();
_ret = mn->ops->invalidate_range_start(mn, range);
if (!mmu_notifier_range_blockable(range))
non_block_end();
if (_ret) {
pr_info("%pS callback failed with %d in %sblockable context.\n",
mn->ops->invalidate_range_start, _ret,
@ -210,8 +216,13 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
mn->ops->invalidate_range(mn, range->mm,
range->start,
range->end);
if (mn->ops->invalidate_range_end)
if (mn->ops->invalidate_range_end) {
if (!mmu_notifier_range_blockable(range))
non_block_start();
mn->ops->invalidate_range_end(mn, range);
if (!mmu_notifier_range_blockable(range))
non_block_end();
}
}
srcu_read_unlock(&srcu, id);
lock_map_release(&__mmu_notifier_invalidate_range_start_map);