From ba170f76b69d1d45a60eaa9ec920c8fddd4c16f3 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 26 Aug 2019 22:14:24 +0200 Subject: [PATCH] mm, notifier: Catch sleeping/blocking for !blockable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 (v1) Reviewed-by: Jérôme Glisse (v4) Signed-off-by: Daniel Vetter Reviewed-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe --- mm/mmu_notifier.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 3f39fb1402db..7fde88695f35 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -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);