The patch titled Subject: mm/hmm: HMM should have a callback before MM is destroyed has been added to the -mm tree. Its filename is mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2.patch
This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-hmm-hmm-should-have-a-callback-b... and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-hmm-hmm-should-have-a-callback-b...
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------------------------------------------------------ From: Ralph Campbell rcampbell@nvidia.com Subject: mm/hmm: HMM should have a callback before MM is destroyed
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/20180316191414.3223-4-jglisse@redhat.com Signed-off-by: Ralph Campbell rcampbell@nvidia.com Signed-off-by: Jérôme Glisse jglisse@redhat.com Cc: Evgeny Baskakov ebaskakov@nvidia.com Cc: Mark Hairgrove mhairgrove@nvidia.com Cc: John Hubbard jhubbard@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
include/linux/hmm.h | 10 ++++++++++ mm/hmm.c | 18 +++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-)
diff -puN include/linux/hmm.h~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2 include/linux/hmm.h --- a/include/linux/hmm.h~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2 +++ a/include/linux/hmm.h @@ -218,6 +218,16 @@ enum hmm_update_type { * @update: callback to update range on a device */ struct hmm_mirror_ops { + /* release() - release hmm_mirror + * + * @mirror: pointer to struct hmm_mirror + * + * This is called when the mm_struct is being released. + * The callback should make sure no references to the mirror occur + * after the callback returns. + */ + void (*release)(struct hmm_mirror *mirror); + /* sync_cpu_device_pagetables() - synchronize page tables * * @mirror: pointer to struct hmm_mirror diff -puN mm/hmm.c~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2 mm/hmm.c --- a/mm/hmm.c~mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2 +++ a/mm/hmm.c @@ -160,6 +160,21 @@ static void hmm_invalidate_range(struct up_read(&hmm->mirrors_sem); }
+static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm) +{ + struct hmm *hmm = mm->hmm; + struct hmm_mirror *mirror; + struct hmm_mirror *mirror_next; + + down_write(&hmm->mirrors_sem); + list_for_each_entry_safe(mirror, mirror_next, &hmm->mirrors, list) { + list_del_init(&mirror->list); + if (mirror->ops->release) + mirror->ops->release(mirror); + } + up_write(&hmm->mirrors_sem); +} + static void hmm_invalidate_range_start(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, @@ -185,6 +200,7 @@ static void hmm_invalidate_range_end(str }
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 +246,7 @@ void hmm_mirror_unregister(struct hmm_mi 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); _
Patches currently in -mm which might be from rcampbell@nvidia.com are
mm-hmm-documentation-editorial-update-to-hmm-documentation.patch mm-hmm-hmm-should-have-a-callback-before-mm-is-destroyed-v2.patch