+ mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/madvise: remove redundant mmap_lock operations from process_madvise()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise.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: SeongJae Park <sj@kernel.org>
Subject: mm/madvise: remove redundant mmap_lock operations from process_madvise()
Date: Wed, 5 Feb 2025 22:15:17 -0800

Optimize redundant mmap lock operations from process_madvise() by directly
doing the mmap locking first, and then the remaining works for all ranges
in the loop.

Link: https://lkml.kernel.org/r/20250206061517.2958-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/madvise.c |   26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

--- a/mm/madvise.c~mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise
+++ a/mm/madvise.c
@@ -1761,9 +1761,26 @@ static ssize_t vector_madvise(struct mm_
 
 	total_len = iov_iter_count(iter);
 
+	ret = madvise_lock(mm, behavior);
+	if (ret)
+		return ret;
+
 	while (iov_iter_count(iter)) {
-		ret = do_madvise(mm, (unsigned long)iter_iov_addr(iter),
-				 iter_iov_len(iter), behavior);
+		unsigned long start = (unsigned long)iter_iov_addr(iter);
+		size_t len_in = iter_iov_len(iter);
+		size_t len;
+
+		if (!is_valid_madvise(start, len_in, behavior)) {
+			ret = -EINVAL;
+			break;
+		}
+
+		len = PAGE_ALIGN(len_in);
+		if (start + len == start)
+			ret = 0;
+		else
+			ret = madvise_do_behavior(mm, start, len_in, len,
+					behavior);
 		/*
 		 * An madvise operation is attempting to restart the syscall,
 		 * but we cannot proceed as it would not be correct to repeat
@@ -1779,12 +1796,17 @@ static ssize_t vector_madvise(struct mm_
 				ret = -EINTR;
 				break;
 			}
+
+			/* Drop and reacquire lock to unwind race. */
+			madvise_unlock(mm, behavior);
+			madvise_lock(mm, behavior);
 			continue;
 		}
 		if (ret < 0)
 			break;
 		iov_iter_advance(iter, iter_iov_len(iter));
 	}
+	madvise_unlock(mm, behavior);
 
 	ret = (total_len - iov_iter_count(iter)) ? : ret;
 
_

Patches currently in -mm which might be from sj@kernel.org are

mm-madvise-split-out-mmap-locking-operations-for-madvise.patch
mm-madvise-split-out-madvise-input-validity-check.patch
mm-madvise-split-out-madvise-behavior-execution.patch
mm-madvise-remove-redundant-mmap_lock-operations-from-process_madvise.patch