From e1401513c6b5efec59678a4d4e9f90957684b7e3 Mon Sep 17 00:00:00 2001 From: Ralph Campbell Date: Tue, 10 Apr 2018 16:28:19 -0700 Subject: mm/hmm: HMM should have a callback before MM is destroyed MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit hmm_mirror_register() registers a callback for when the CPU pagetable is modified. Normally, the device driver will call hmm_mirror_unregister() when the process using the device is finished. However, if the process exits uncleanly, the struct_mm can be destroyed with no warning to the device driver. Link: http://lkml.kernel.org/r/20180323005527.758-4-jglisse@redhat.com Signed-off-by: Ralph Campbell Signed-off-by: Jérôme Glisse Reviewed-by: John Hubbard Cc: Evgeny Baskakov Cc: Mark Hairgrove Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hmm.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/hmm.c b/mm/hmm.c index 320545b98ff5..8116727766f7 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -160,6 +160,32 @@ static void hmm_invalidate_range(struct hmm *hmm, up_read(&hmm->mirrors_sem); } +static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm) +{ + struct hmm_mirror *mirror; + struct hmm *hmm = mm->hmm; + + down_write(&hmm->mirrors_sem); + mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror, + list); + while (mirror) { + list_del_init(&mirror->list); + if (mirror->ops->release) { + /* + * Drop mirrors_sem so callback can wait on any pending + * work that might itself trigger mmu_notifier callback + * and thus would deadlock with us. + */ + up_write(&hmm->mirrors_sem); + mirror->ops->release(mirror); + down_write(&hmm->mirrors_sem); + } + mirror = list_first_entry_or_null(&hmm->mirrors, + struct hmm_mirror, list); + } + up_write(&hmm->mirrors_sem); +} + static void hmm_invalidate_range_start(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, @@ -185,6 +211,7 @@ static void hmm_invalidate_range_end(struct mmu_notifier *mn, } static const struct mmu_notifier_ops hmm_mmu_notifier_ops = { + .release = hmm_release, .invalidate_range_start = hmm_invalidate_range_start, .invalidate_range_end = hmm_invalidate_range_end, }; @@ -230,7 +257,7 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror) struct hmm *hmm = mirror->hmm; down_write(&hmm->mirrors_sem); - list_del(&mirror->list); + list_del_init(&mirror->list); up_write(&hmm->mirrors_sem); } EXPORT_SYMBOL(hmm_mirror_unregister); -- cgit v1.2.3-59-g8ed1b