diff options
author | Jérôme Glisse <jglisse@redhat.com> | 2018-04-10 16:28:23 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-11 10:28:30 -0700 |
commit | c01cbba2aa8b4d05607d373b02fe9e4eda5c0591 (patch) | |
tree | b582ce8d27f21d4766ff5891d7d149404a8cc7ce /mm/hmm.c | |
parent | e1401513c6b5efec59678a4d4e9f90957684b7e3 (diff) | |
download | linux-c01cbba2aa8b4d05607d373b02fe9e4eda5c0591.tar.bz2 |
mm/hmm: unregister mmu_notifier when last HMM client quit
This code was lost in translation at one point. This properly call
mmu_notifier_unregister_no_release() once last user is gone. This fix the
zombie mm_struct as without this patch we do not drop the refcount we have
on it.
Link: http://lkml.kernel.org/r/20180323005527.758-5-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r-- | mm/hmm.c | 38 |
1 files changed, 35 insertions, 3 deletions
@@ -233,13 +233,24 @@ int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm) if (!mm || !mirror || !mirror->ops) return -EINVAL; +again: mirror->hmm = hmm_register(mm); if (!mirror->hmm) return -ENOMEM; down_write(&mirror->hmm->mirrors_sem); - list_add(&mirror->list, &mirror->hmm->mirrors); - up_write(&mirror->hmm->mirrors_sem); + if (mirror->hmm->mm == NULL) { + /* + * A racing hmm_mirror_unregister() is about to destroy the hmm + * struct. Try again to allocate a new one. + */ + up_write(&mirror->hmm->mirrors_sem); + mirror->hmm = NULL; + goto again; + } else { + list_add(&mirror->list, &mirror->hmm->mirrors); + up_write(&mirror->hmm->mirrors_sem); + } return 0; } @@ -254,11 +265,32 @@ EXPORT_SYMBOL(hmm_mirror_register); */ void hmm_mirror_unregister(struct hmm_mirror *mirror) { - struct hmm *hmm = mirror->hmm; + bool should_unregister = false; + struct mm_struct *mm; + struct hmm *hmm; + + if (mirror->hmm == NULL) + return; + hmm = mirror->hmm; down_write(&hmm->mirrors_sem); list_del_init(&mirror->list); + should_unregister = list_empty(&hmm->mirrors); + mirror->hmm = NULL; + mm = hmm->mm; + hmm->mm = NULL; up_write(&hmm->mirrors_sem); + + if (!should_unregister || mm == NULL) + return; + + spin_lock(&mm->page_table_lock); + if (mm->hmm == hmm) + mm->hmm = NULL; + spin_unlock(&mm->page_table_lock); + + mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm); + kfree(hmm); } EXPORT_SYMBOL(hmm_mirror_unregister); |