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.
Reviewed-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
mm/madvise.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index 31e5df75b926..5a0a1fc99d27 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1754,9 +1754,26 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter,
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
@@ -1772,12 +1789,17 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter,
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;
--
2.39.5
