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mm/mmu_notifier: finish non-blocking interval invalidation on error

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When an ordinary MMU notifier rejects a non-blocking invalidation, the
interval invalidation started beforehand is left unfinished: the caller
skips mmu_notifier_invalidate_range_end(). Subsequent interval notifier
operations can then wait forever.

The only in-tree trigger is nouveau SVM, which uses both notifier types
and rejects non-blocking invalidations. Reaping via the OOM reaper or
process_mrelease() can therefore leave the GPU fault worker stuck,
holding a reference that prevents the dying process's address space
and memory from being freed.

End the interval invalidation when an ordinary notifier fails a
non-blocking invalidation, like mn_itree_invalidate() already does when
an interval notifier fails. Make that handling clearer in the
documentation of mmu_notifier_invalidate_range_start_nonblock().

Fix generated by an LLM and sent by Josef Bacik in private.

Fixes: 99cb252f5e ("mm/mmu_notifier: add an interval tree notifier")
Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ david: simplify description, update function doc ]
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Link: https://patch.msgid.link/20261031-fixes_core-v3-28-d6437171ecc3@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
This commit is contained in:
Josef Bacik 2026-10-31 10:39:57 +01:00 committed by David Hildenbrand (Arm)
parent 64ae7959a1
commit 6d65925777
2 changed files with 15 additions and 5 deletions
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3
include/linux/mmu_notifier.h
View File

@ -483,7 +483,8 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
/*
* This version of mmu_notifier_invalidate_range_start() avoids blocking, but it
* can return an error if a notifier can't proceed without blocking, in which
* case you're not allowed to modify PTEs in the specified range.
* case you're not allowed to modify PTEs in the specified range or call
* mmu_notifier_invalidate_range_end().
*
* This is mainly intended for OOM handling.
*/

17
mm/mmu_notifier.c
View File

@ -569,16 +569,25 @@ int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
struct mmu_notifier_subscriptions *subscriptions =
range->mm->notifier_subscriptions;
int ret;
const bool has_itree = subscriptions->has_itree;
int ret = 0;
if (subscriptions->has_itree) {
if (has_itree) {
ret = mn_itree_invalidate(subscriptions, range);
if (ret)
return ret;
}
if (!hlist_empty(&subscriptions->list))
return mn_hlist_invalidate_range_start(subscriptions, range);
return 0;
ret = mn_hlist_invalidate_range_start(subscriptions, range);
/*
* On error, the non-blocking caller is not allowed to call
* invalidate_range_end(), as in mn_itree_invalidate().
*/
if (ret && has_itree && !mmu_notifier_range_blockable(range))
mn_itree_inv_end(subscriptions);
return ret;
}
static void