+ mm-document-mmu_notifier_invalidate_range_start_nonblock.patch added to mm-unstable branch

+ mm-document-mmu_notifier_invalidate_range_start_nonblock.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: document mmu_notifier_invalidate_range_start_nonblock()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-document-mmu_notifier_invalidate_range_start_nonblock.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-document-mmu_notifier_invalidate_range_start_nonblock.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Jann Horn <jannh@google.com>
Subject: mm: document mmu_notifier_invalidate_range_start_nonblock()
Date: Mon, 18 Sep 2023 22:18:32 +0200

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.

Link: https://lkml.kernel.org/r/20230918201832.265108-1-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mmu_notifier.h |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/include/linux/mmu_notifier.h~mm-document-mmu_notifier_invalidate_range_start_nonblock
+++ a/include/linux/mmu_notifier.h
@@ -459,7 +459,14 @@ mmu_notifier_invalidate_range_start(stru
 	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;
_

Patches currently in -mm which might be from jannh@google.com are

mm-document-mmu_notifier_invalidate_range_start_nonblock.patch