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
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
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@xxxxxxxxxx
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx 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
