On 20/02/2025 23:52, Matthew Brost wrote:
On Mon, Feb 17, 2025 at 07:58:11PM -0800, Matthew Brost wrote:
On Mon, Feb 17, 2025 at 09:38:26AM +0000, Matthew Auld wrote:
On 15/02/2025 01:28, Matthew Brost wrote:
On Fri, Feb 14, 2025 at 05:05:28PM +0000, Matthew Auld wrote:
On error restore anything still on the pin_list back to the invalidation
list on error. For the actual pin, so long as the vma is tracked on
either list it should get picked up on the next pin, however it looks
possible for the vma to get nuked but still be present on this per vm
pin_list leading to corruption. An alternative might be then to instead
just remove the link when destroying the vma.
Fixes: ed2bdf3b264d ("drm/xe/vm: Subclass userptr vmas")
Suggested-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v6.8+
---
drivers/gpu/drm/xe/xe_vm.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index d664f2e418b2..668b0bde7822 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -670,12 +670,12 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
list_for_each_entry_safe(uvma, next, &vm->userptr.invalidated,
userptr.invalidate_link) {
list_del_init(&uvma->userptr.invalidate_link);
- list_move_tail(&uvma->userptr.repin_link,
- &vm->userptr.repin_list);
+ list_add_tail(&uvma->userptr.repin_link,
+ &vm->userptr.repin_list);
Why this change?
Just that with this patch the repin_link should now always be empty at this
point, I think. add should complain if that is not the case.
If it is always expected to be empty, then yea maybe add a xe_assert for
this as the list management is pretty tricky.
}
spin_unlock(&vm->userptr.invalidated_lock);
- /* Pin and move to temporary list */
+ /* Pin and move to bind list */
list_for_each_entry_safe(uvma, next, &vm->userptr.repin_list,
userptr.repin_link) {
err = xe_vma_userptr_pin_pages(uvma);
@@ -691,10 +691,10 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
err = xe_vm_invalidate_vma(&uvma->vma);
xe_vm_unlock(vm);
if (err)
- return err;
+ break;
} else {
- if (err < 0)
- return err;
+ if (err)
+ break;
list_del_init(&uvma->userptr.repin_link);
list_move_tail(&uvma->vma.combined_links.rebind,
@@ -702,7 +702,19 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
}
}
- return 0;
+ if (err) {
+ down_write(&vm->userptr.notifier_lock);
Can you explain why you take the notifier lock here? I don't think this
required unless I'm missing something.
For the invalidated list, the docs say:
"Removing items from the list additionally requires @lock in write mode, and
adding items to the list requires the @userptr.notifer_lock in write mode."
Not sure if the docs needs to be updated here?
Oh. I believe the part of comment for 'adding items to the list
requires the @userptr.notifer_lock in write mode' really means something
like this:
'When adding to @vm->userptr.invalidated in the notifier the
@userptr.notifer_lock in write mode protects against concurrent VM binds
from setting up newly invalidated pages.'
So with above and since this code path is in the VM bind path (i.e. we
are not racing with other binds) I think the
vm->userptr.invalidated_lock is sufficient. Maybe ask Thomas if he
agrees here.
After some discussion with Thomas, removing notifier lock here is safe.
Thanks for confirming.
However, for adding is either userptr.notifer_lock || vm->lock to also
avoid races between binds, execs, and rebind worker.
I'd like update the documentation and add a helper like this:
void xe_vma_userptr_add_invalidated(struct xe_userptr_vma *uvma)
{
struct xe_vm *vm = xe_vma_vm(&uvma->vma);
lockdep_assert(lock_is_held_type(&vm->lock.dep_map, 1) ||
lock_is_held_type(&vm->userptr.notifier_lock.dep_map, 1));
spin_lock(&vm->userptr.invalidated_lock);
list_move_tail(&uvma->userptr.invalidate_link,
&vm->userptr.invalidated);
spin_unlock(&vm->userptr.invalidated_lock);
}
Sounds good.
However, let's delay the helper until this series and recently post
series of mine [1] merge as both are fixes series and hoping for a clean
backport.
Makes sense.
Matt
[1] https://patchwork.freedesktop.org/series/145198/
Matt
Matt
+ spin_lock(&vm->userptr.invalidated_lock);
+ list_for_each_entry_safe(uvma, next, &vm->userptr.repin_list,
+ userptr.repin_link) {
+ list_del_init(&uvma->userptr.repin_link);
+ list_move_tail(&uvma->userptr.invalidate_link,
+ &vm->userptr.invalidated);
+ }
+ spin_unlock(&vm->userptr.invalidated_lock);
+ up_write(&vm->userptr.notifier_lock);
+ }
+ return err;
}
/**
--
2.48.1
