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Subject[patch -mm] mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks fix fix
Fix mmu_notifier.h comments in "mm, mmu_notifier: annotate mmu notifiers
with blockable invalidate callbacks".

mmu_notifier_invalidate_range_end() can also call the invalidate_range()
callback, so it must not block for MMU_INVALIDATE_DOES_NOT_BLOCK to be
set.

Also remove a bogus comment about invalidate_range() always being called
under the ptl spinlock.

Signed-off-by: David Rientjes <rientjes@google.com>
---
include/linux/mmu_notifier.h | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -34,8 +34,8 @@ struct mmu_notifier_ops {
* Flags to specify behavior of callbacks for this MMU notifier.
* Used to determine which context an operation may be called.
*
- * MMU_INVALIDATE_DOES_NOT_BLOCK: invalidate_{start,end} does not
- * block
+ * MMU_INVALIDATE_DOES_NOT_BLOCK: invalidate_range_* callbacks do not
+ * block
*/
int flags;

@@ -151,8 +151,9 @@ struct mmu_notifier_ops {
* address space but may still be referenced by sptes until
* the last refcount is dropped.
*
- * If both of these callbacks cannot block, mmu_notifier_ops.flags
- * should have MMU_INVALIDATE_DOES_NOT_BLOCK set.
+ * If both of these callbacks cannot block, and invalidate_range
+ * cannot block, mmu_notifier_ops.flags should have
+ * MMU_INVALIDATE_DOES_NOT_BLOCK set.
*/
void (*invalidate_range_start)(struct mmu_notifier *mn,
struct mm_struct *mm,
@@ -175,12 +176,13 @@ struct mmu_notifier_ops {
* external TLB range needs to be flushed. For more in depth
* discussion on this see Documentation/vm/mmu_notifier.txt
*
- * The invalidate_range() function is called under the ptl
- * spin-lock and not allowed to sleep.
- *
* Note that this function might be called with just a sub-range
* of what was passed to invalidate_range_start()/end(), if
* called between those functions.
+ *
+ * If this callback cannot block, and invalidate_range_{start,end}
+ * cannot block, mmu_notifier_ops.flags should have
+ * MMU_INVALIDATE_DOES_NOT_BLOCK set.
*/
void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
unsigned long start, unsigned long end);
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