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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/20180323005527.758-4-jglisse@redhat.com
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ralph Campbell 2018-04-10 16:28:19 -07:00 committed by Linus Torvalds
parent b28b08de43
commit e1401513c6
2 changed files with 38 additions and 1 deletions
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10
include/linux/hmm.h
View File

@ -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

29
mm/hmm.c
View File

@ -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);