2023-09-19 02:21:36

by Jann Horn

Subject: [PATCH] mm: document mmu_notifier_invalidate_range_start_nonblock()

Document what mmu_notifier_invalidate_range_start_nonblock() is for.
Also add a __must_check annotation to signal that callers must bail out if
a notifier vetoes the operation.

Signed-off-by: Jann Horn <[email protected]>
---
include/linux/mmu_notifier.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 6e3c857606f1..f349e08a9dfe 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -459,7 +459,14 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
lock_map_release(&__mmu_notifier_invalidate_range_start_map);
}

-static inline int
+/*
+ * 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.
+ *
+ * This is mainly intended for OOM handling.
+ */
+static inline int __must_check
mmu_notifier_invalidate_range_start_nonblock(struct mmu_notifier_range *range)
{
int ret = 0;

base-commit: 6704c78e2963a5682b4ac3c0e609d36f2405cf17
--
2.42.0.459.ge4e396fd5e-goog

2023-09-19 06:25:11

by Alistair Popple

Subject: Re: [PATCH] mm: document mmu_notifier_invalidate_range_start_nonblock()

Looks good, thanks.

Reviewed-by: Alistair Popple <[email protected]>

Jann Horn <[email protected]> writes:

> Document what mmu_notifier_invalidate_range_start_nonblock() is for.
> Also add a __must_check annotation to signal that callers must bail out if
> a notifier vetoes the operation.
>
> Signed-off-by: Jann Horn <[email protected]>
> ---
> include/linux/mmu_notifier.h | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index 6e3c857606f1..f349e08a9dfe 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -459,7 +459,14 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
> lock_map_release(&__mmu_notifier_invalidate_range_start_map);
> }
>
> -static inline int
> +/*
> + * 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.
> + *
> + * This is mainly intended for OOM handling.
> + */
> +static inline int __must_check
> mmu_notifier_invalidate_range_start_nonblock(struct mmu_notifier_range *range)
> {
> int ret = 0;
>
> base-commit: 6704c78e2963a5682b4ac3c0e609d36f2405cf17

2023-09-19 09:36:34

by Jason Gunthorpe

Subject: Re: [PATCH] mm: document mmu_notifier_invalidate_range_start_nonblock()

On Mon, Sep 18, 2023 at 10:18:32PM +0200, Jann Horn wrote:
> Document what mmu_notifier_invalidate_range_start_nonblock() is for.
> Also add a __must_check annotation to signal that callers must bail out if
> a notifier vetoes the operation.
>
> Signed-off-by: Jann Horn <[email protected]>
> ---
> include/linux/mmu_notifier.h | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)

Reviewed-by: Jason Gunthorpe <[email protected]>

Jason